GH - October 2023

Finding the right recipe

An overview of recent research on growing under LED light | 18

Media amendments

A closer look at Biochar and Zeolite | 36

Beneficial silicon Hydropnic crops respond well to this often overlooked element | 38

OCTOBER 2023

greenhousecanada.com

Structure Design

Installation

Heating & Ventilation Systems

Rolling Benches

Charged Carbon

Insights on this new standalone growing media gaining international attention. Page 8

Editorial 4

Industry News 6

Year-round destination 14

Independent garden centres get creative in the off-season.

The science of lighting 18 Research from Agriculture and Agri-Food Canada’s Harrow Research and Development Centre.

Highfield Farm 26

Former industrial landscape in Calgary finds new life as an urban agricultural hub.

Mum nutrients 32

Modified application strategy lowers production costs, improves plant health.

Media amendments 36 Niagara College study shows promise for reducing fertilizer loss. Inside View 54

Microgreens grown using Charged Carbon, a new standalone growing media developed by Alberta’s Pure Life Carbon. (Photo courtesy Pure Life Carbon).

Recent studies have shown that this element can help reduce plant stress.

DR. MUHAMMAD

Illuminating IPM

Effect of LED lighting on pests and how to tweak management strategies.

SARAH

Common ground

Recent community event in Ontario brought tomato growers from across the world together to learn about lighting.

BY KERSTIN POEHLMANN

FROM THE EDITOR

AMY KOUNIAKIS | @GreenHouseCan

CGC season: Best time of the year

October is perhaps one of my most favourite months of the year. The dog days of summer are well behind us, the kids have settled into the school-year routine by now, we get to celebrate Halloween and Thanksgiving and let’s not forget that it’s the month the Canadian greenhouse industry comes together in Niagara Falls for two days to do business, share knowledge and network. What more could we want?

of Niagara College shows several soil amendments can help reduce fertilizer loss, while research out of the University of Guelph, shows much promise in improving plant health and cutting costs by reducing nutrient inputs in mums.

Garden centres, typically a hive of activity in the spring and summer months, go through quite a change in the gardening off-seasons. In order to keep customers coming through the door, independent garden centres have to get creative. This month, readers will hear from some Canadian entrepreneurs who have had some success in making their garden centre a year-round destination.

Finally, as the days grow shorter, lighting becomes even more top of mind for growers and, as such, is one of this month’s themes for the magazine. Drs. Fadi Al-Daoud (OMAFRA) and Xiuming Hao (AAFC) have written an in-depth review of some of the lighting research conducted at Agriculture and AgriFood Canada’s Harrow Research and

“As days grow shorter, lighting becomes even more top of mind.”

The Canadian Greenhouse Conference kicks off on Oct. 4 and features a roster of some of the industry’s brightest minds and experts sharing the latest research, innovations and insights on this always changing business landscape. It’s a great opportunity to come out and take stock of how this past year treated you and your business and to see what (and who) is out there to help you get ahead in 2024. This year’s conference features a sold-out trade show floor as well as two days of talks and presentations on issues like sustainability, IPM, irrigation and pesticide use, production, lighting, technology and automation and much more. To learn more about the event or to register, visit the Canadian Greenhouse Conference website.

In this month’s Greenhouse Canada magazine, we’re exploring rootzone management, particularly growing media and nutrition that contribute to creating a healthy rootzone. Writer Treena Hein offers an in-depth look at Charged Carbon, a new standalone, sustainable growing media launched by Alberta’s Pure Life Carbon that is gaining attention across the globe. Additionally, research out

Development Centre over the past several years, starting on page 18. Lighting also brought tomato growers together in Ontario earlier this year for an event hosted by Philips Horticulture to learn about growing under LED lights. Learn more about this on page 48.

In the meantime, Greenhouse Canada can be found at booth #2000 at this year’s CGC. If we don’t have a chance to connect at the show, please feel free to reach out to me at akouniakis@annexbusinessmedia. com.

New online resource library for Thrips and Botrytis

The American Floral Endowment (AFE) announced the release of a new online Thrips and Botrytis Research Library (https://endowment.org/tb/). This library is the result of a special research campaign, established in 2017, to address the control and management of Thrips and Botrytis. It launched in August for free to all thanks to the campaign’s industry sponsors. This comprehensive online resource is designed to be a one-stop-shop, complete with informative webinars,

insightful fact sheets, and engaging articles on the latest research and implementation strategy. It contains resources in both English and Spanish, as well as cutting-edge research reports that growers can use and implement into their business immediately.

This resource will continue to be updated as new research findings emerge and as AFE persists in its mission of tackling the challenges faced by the floral industry.

Syngenta Canada names new head of sales, crop protection

Syngenta Canada Inc. has named Shaun Vey as Head of Sales, Crop Protection. Vey leads the national sales and key account team from the company’s office in Calgary and serves on the organization’s leadership team.

Vey has held various roles at Syngenta for the past 14 years, primarily with the Canadian organization. Most recently, he gained international experience as Head of Marketing for Syngenta UK, Ireland & Nordics. In his new

Construction begins on Dramm’s research greenhouse

Construction has started on Dramm’s new research greenhouse. The addition to the new factory and headquarters will allow for easier development and testing of new products and techniques. The new 2,500 sq.-ft. facility will feature several cropping systems, from fixed and movable benches to hydroponic systems. Various water sources will be used, from rainwater and pond water to recycled and municipal water.

Multiple water treatment systems will be installed for regular use andto test different methods and tools for best efficacy with different sources and water qualities. Trials of the Drammatic® Organic Fertilizer will be conducted in the greenhouse. Another benefit willbe growing plants for Dramm’s lobby “green wall” and flowers for spring planting.

Completion of the facility is scheduled for early-Fall for 2023, allowing for the first crops and research work to begin this winter.

role, Vey will work with his team across nine provinces to build best-in-class customer experience, delivering innovative solutions with a focus on sustainability and quality.

“It’s great to be back with the Canadian

team, serving growers and working with retail partners. I look forward to deepening our customer and industry relationships and advancing Canadian agriculture,” says Vey.

“I’m grateful for the many opportunities throughout my Syngenta career that have prepared me for this role.”

BY THE NUMBERS

Consumer attitudes about the economy

75% of Canadian households think inflation will increase further in the next few months.

26% of surveyed consumers plan to cut back spending on home and garden supplies.

Consumer financial concern remains high and 58% of consumers rate their level of concern for the economy as 8/10 or higher.

CHARGED Carbon

This new stand-alone growing medium from Alberta’s Pure Life Carbon gains international interest

BY TREENA HEIN

BELOW

Charged Carbon is a standalone growing media that is reusable and sustainable.

Growing media is a critical component of greenhouse crop production, in terms of cost, but also sustainability and food safety, with contamination concerns on the rise across the industry. In addition, during the past two years due to supply chain issues and strong demand, availability of several media types was a serious issue for some growers in Canada and beyond. For all these reasons, new cost-effective, food-safe and sustainable media options are always welcome.

On the sustainability front, all conventional growing mediums are single use. Stonewool products, perlite and vermiculite must be landfilled. Peat is not renewable and can only be harvested in some areas of the world (indeed, it will be banned as a greenhouse growing medium in England and Ireland by 2030). Peat, bark, wood fibre and coconut fibre are compostable and all of those but peat are renewable, but must be shipped very long distances in some cases. And due to time, cost and space needed to compost at greenhouse sites, all these mediums tend to be landfilled.

‘Charged Carbon’ is a new product in a class all its own that’s both reusable and sustainable, with the feedstock being crops or trees. It hit the market in 2022, launched by Pure Life Carbon (PLC) of Alberta after an enormous amount of R&D to develop the product and scale up its manufacture. It’s the only standalone carbon growing media so far available on the global market. Its manufacture starts with a specific type of bamboo biomass

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In cucumber trials, much lower volumes of Charged Carbon provided better performance in the three main yield parameters.

being converted through multiple compounding steps including carbonization/pyrolysis and advanced chemical manipulation.

There was, and still is, a haphazard use of words to describe our product...

Its development was built on years of research done by Dr. Nick Savidov, a scientist currently at the Centre for Sustainable Food Production at Lethbridge College in Alberta. His work with carbon growing media began two decades ago, when he noted the investigations of colleagues into pyrolyzed carbon (charcoal) as a soil amendment for field crops. He also came across a paper from research outside Canada using pyrolyzed carbon in orchid production.

Savidov got samples from this group, worked on treatments to reduce alkalinity and did greenhouse experiments with impressive results.

COMMERCIALIZATION

PLC has invested more than $24 million to advance Dr. Savidov’s work, to create a scalable commercial

process around their combined learnings and to do extensive additional testing. Before we look at test results however, it’s important to clarify the carbon product landscape. PLC CEO Ryan Rand first notes that there are various products available intended for different end uses. “We as a company celebrate the range of these products, but while some of them function very well blended into other soilless substrates or as soil augmentations, not all of them do so,” he explains.

“And our trademarked flagship product, Charged Carbon, is the only standalone carbon-based growing medium we are aware of anywhere around the world. We feel quite confident making that statement because we are in close contact with the greenhouse sectors in every country that has one. Unfortunately, there is quite a lot of confusion about products. What has become clear to us is that there was, and still is, a haphazard use of words to describe

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Charged Carbon can be re-used, but must undergo the ‘ReCharging’ process and for this reason, the product is leased to growers.

our product. It is being referred to by those in both academic circles and in some industry circles as biochar, black carbon, carbon black, bamboo carbon, charcoal, the list goes on. This is a really dangerous thing for greenhouse operators and for us, because we see them trying other products with results that put their businesses at risk and they then paint all products with the same negative brush.”

Similarly, Rand explains that the trademarked name ‘Charged Carbon’ is being used to describe other products that are being used in growing medium blends. “We hope that this article,” he says, “will clear up the confusion.”

STUDIES COMPLETED

At this point PLC has conducted over 50 commercial greenhouse trials throughout Europe and North America. The many large-scale industry partners involved in these studies cannot be named publicly, and most test results are private, but Rand can share some general results.

“These studies have proven

Charged Carbon provides similar or better results in the main three yield parameters (number of vegetables/ fruit, weight and consistency) for all the main greenhouse crops than coco, peat or stonewool,” he says. “Commercial tomato production result in higher Brix values compared to Grodan Rockwool in trials optimized for Grodan.”

In cucumber trials where seven litres of Grodan were used per plant (industry standard), much lower volumes of Charged Carbon (2.5, 3.5. 4.5 litres) all provided better performance in the three main yield parameters. Microgreens perform similarly on peat versus Charged Carbon at 50 per cent of the peat volume. Rand adds that “spinach germinates and grows well on Charged Carbon, which is a crop most of the industry struggles to grow at scale. I can provide more detailed results for growers who contact us and are partnership candidates.”

The most recent study is occurring at the renowned Vineland Research and Innovation Centre in southern

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Trials of Charged Carbon in commercial tomato production resulted in higher Brix values.

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Pure Life Carbon built a 40,000 sq.-ft. production facility in Red Deer, Alta where 10,000,000 litres of Charged Carbon can be produced annually.

Ontario (an independent organization supported partly by federal/provincial funding with research on greenhouse, vineyard and horticulture crops). “We were not involved at all in this study,” says Rand, “and although the details will not be published until October or so, we can say that the results are incredibly promising for year-round cucumber production. In the offseason, compared to standard Grodan Rockwool, cucumbers on three different volumes of Charged Carbon substantially outperformed, with the fertigation schedule optimized for Grodan. The next round of studies will compare Charged Carbon with all other growing media, with fertigation optimized for each.”

As mentioned, Charged Carbon can be re-used, but must undergo the ‘ReCharging’ process. “The ReCharged Charged Carbon performs as well as or better than first-use Charged Carbon,” says Rand. “Because of this aspect of our product, we actually lease it to growers and don’t sell it. This results in less cost for growers than using other media per crop cycle. We drop off new product and pick up used product for ReCharging. During this process, the Charged

Carbon is analyzed and the root mass is separated and used as animal feed or composted. The Charged Carbon is cleaned of contaminants, sterilized and then sent out for extensive testing by a third-party lab to confirm there are no contaminants present. Then the ReCharged Charged Carbon is certified, assigned a batch number, packaged and sent back out into use.”

MARKET EXPANSION

In December 2021, PLC raised $13 million in investment, enabling it to build its first 40,000 sq.-ft. production facility in Red Deer County, Alta. Here, 10,000,000 litres of Charged Carbon can be produced per year.

“We’re now in the process of finalizing sales with some of the very largest and most-reputable growers in North America and around the world,” Rand reports. “In June, we had an incredibly successful launch at ‘Indoor Agtech’ in New York city. We are also seeing a profound amount of interest in our product from growers in Europe because, as mentioned, the use of peat moss will not be permitted anymore starting in 2030 in some countries and growers close

ABOVE Microgreens grow just as well or even better with half the amount of Charged Carbon.

ReCharged Charged Carbon performs as well as or better than first-use Charged Carbon.

Studies have shown some crops growers struggle with, germinate and grow well on Charged Carbon year-round.

to these regions know its just a matter of time before that spreads to their countries as well. These growers are desperate for a sustainable and scalable product to maintain current production levels and to further expand. It appears that peat use for greenhouse production will be a focus to ban globally as new growing mediums are better alternatives for production and sustainability.”

Serving these markets means that Rand and his team will continue to educate growers about the differences between products intended for blending and standalone Charged Carbon.

“We fully understand that that some growers have tried a pyrolyzed carbon product and have had poor results and they are therefore wary of trying any other carbon products,” he says. “We will encourage them to try our product by showing them the extensive study results. We are very excited to be offering

are razor thin and more sustainability is required across all types of food production. We think that greenhouse,

and

depends on having sustainable, cost-effective, foodsafe growing mediums. Future food security depends on it.”

Managing the Root Zone

Put life back in the soil

• For seed treatments, transplants & established crop root drench.

• Improved root protection & germination rates

• Increased root absorption area & nutrient use efficiency

• Apply as a root drench or foliar spray

• Improved seed germination, Lateral rooting & root mass

• Improved pollen tube elongation / fruit set, cell expansion & fruit fill

• Improved root growth & water use efficiency

• Regulates nutritional deficiency

• Increased resiliency against crop stress

www.belchimcanada.com

Mycorrhizae & Trichoderma Inoculant

Concentrated Liquid Seaweed Extract from Ecklonia Maxima

greenhouse operators a new growing medium option at a time when margins

indoor vertical farming and aquaponics will all expand,

that

Activities and workshops turn independent garden centres into year-round destinations

Even when nothing grows outside, these entrepreneurs find creative ways to cultivate business

BY ANNE KADWELL AND STUART SERVICE, CANADIAN NURSERY LANDSCAPE ASSOCIATION

The seasonality of a garden centre business is focused on making the most of the peak growing season, accumulating most of their annual revenues during the spring and summer period. However, this limited sales window continues to widen as more independent garden centres across Canada discover successful ways to make it economically viable to keep their stores open during the months when nothing grows outside.

By creating a year-round destination shopping experience, garden centres are drawing customers in by hosting workshops, expanding product inventory, and organizing fun community events.

A great example are the many events hosted at Greenland Garden Centre in Sherwood Park,

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Alberta. These include an Indoor Gardening Day in February with seminars and in-store specials, and a Howl-ween Pooch Parade in October, when customers dress up their pets in support of a local animal shelter. And the fashion shows, which have been going on since 2010, continue to be as popular as they are profitable. Greenland currently hosts shows twice a year during the bookends of the gardening season in March and September.

“Both are much anticipated by our customers and sell out quickly every time,” said Greenland General Manager Patti Ambrock. “Our fashion buyer Sharon plans specific outfits to be featured and sets aside a portion of clothing inventory to be showcased exclusively at the event. The models are

Tanya Olsen from Royal City Nursery began opening her garden centre year-round about eight years ago. Along with hosting events in off-peak months like fashion shows, and organizing numerous workshops related to trending gardening topics, Olsen said that one of the most beneficial aspects of year-round store hours is that it’s greatly improved staff retention.

PHOTO: STUART SERVICE

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Karin and Chris Griffin, owners of Alternative Choice Garden Centre in Brandon, Manitoba, frequently host well-attended workshops and events in the wintertime such as Lady’s Night, Gen Z Night, and Games Night. “The marketing team has really put together a lot of different things throughout the year that can attract clients to continue to come in and experience something different,” Chris said.

Greenland’s very own staff members who also work on the sales floor after the show.”

Registration fees, as well as raffle draws throughout the evening, go towards a local women’s shelter. Attendees also receive a complimentary glass of wine.

“It has become a fun evening out for so many of our customers that many attend year after year.”

In October over at Kiwi Nurseries Ltd., this Spruce Grove, Alberta, garden centre hosts a haunted house so popular that it causes traffic to back up on the adjacent Yellowhead Highway. Owner Ashleigh Munroe chuckled when recalling how often customers introduced to her nursery through the haunted house

LEFT

Jordan and Debbie Hiebert from Lacoste Garden Centre in Winnipeg say their store’s customer experience requires multiple reasons to visit. “We always make sure there’s three things on the go –there’s always got to be three reasons to visit us and not just one,” Jordan said. “We always have clothing at our boutique, tropical plants, pottery, and accessories for the home garden. And we always have coffee.”

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Kiwi Nurseries Ltd. goes all out with numerous events throughout the year including craft beer day, Easter egg hunts, pumpkin carving, numerous workshops, and a popular haunted house.

are surprised to discover Kiwi is also a 200-acre tree farm that has been in business for more than 40 years.

For their 40th anniversary, the company marked the occasion by hosting 40 events throughout the year. From the Easter Egg Hunt to Kids at Kiwi classes, and from Craft Beer Night to numerous informational workshops and talks, the overwhelming response has led the company to continue their ambitious event planning.

Leanne Johnson, president of Canada GardenWorks Ltd., frequently works with businesses in the communities local to her 10 store locations in British Columbia. They host meetings for garden clubs and special holiday events for the clients of realtors.

“We’d invite them to the store, have music, snacks, beverages,

PHOTO: STUART SERVICE

PHOTO: STUART SERVICE

PHOTO: KIWI NURSERIES

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In the early winter months, Cedarcrest Gardens in Saint John, New Brunswick, hosts information seminars about different topics and trends. The sessions are free of charge, and customers receive coupons to use on items that relate to that session.

and the realtor is there welcoming them and providing them a nice holiday gift,” she said.

They’ve done similar exclusive events for VIP customers to give them a chance to see new merchandise and to feel valued. They’ve also hosted financial institutions to invite-only parties that include hands-on workshops.

“We just had to provide the expertise and passion,” she added. “That was easy.”

Art Vanden Enden, who worked for more than 40 years at Weall and Cullen and Sheridan Nurseries, and is now a horticultural advisor, said opportunities during offpeak gardening seasons are found in the marketing and merchandising around drawing customers into the store.

“By selling tropical plants, and having water features like fountains running – possibly ponds with fish and turtles –they’ll have already created an oasis many people will love to browse and to escape the dreary winter.”

Discovering niche events that bring people in is an ongoing process that may require some trial and error, as every garden centre has a demographic that differs from place to place.

“Discovering the type of event that works in your area can only occur by trying something new,” said Garden Centres Canada Chair Robin Godfrey. “This fall and winter, take a step outside of the box and give workshops and community events a try, as they may end up being a hit.”

PHOTO: CEDARCREST GARDENS

Finding the right recipe

Review of recent greenhouse vegetable lighting research at Agriculture and Agri-Food Canada’s Harrow Research and Development Centre

SUMMARY AND CONCLUSIONS

BY DR. FADI AL-DAOUD (ONTARIO MINISTRY OF AGRICULTURE, FOOD AND RURAL AFFAIRS)

AND

DR. XIUMING HAO (AGRICULTURE AND AGRI-FOOD CANADA)

The market demand for locally grown fruits and vegetables year-round has driven adoption of lighting technologies for winter food production in greenhouses and vertical farms in Ontario. Here, we review some of the lighting research conducted at Agriculture and Agri-Food Canada’s Harrow Research and Development Centre (Harrow, Ont.) over the past several years. Generalized recommendations for light intensity, photoperiod and daily light integral (DLI) are summarized in Table 2 for practical commercial greenhouse production using overhead lighting (HPS, LED, or a hybrid system of HPS and LED). This article also highlights a few studies conducted in Harrow to test different combinations of overhead, interlighting, and dynamic long photoperiod, low intensity lighting recipes for winter production of cucumbers, tomatoes, peppers, and microgreens.

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You will find detailed information about the light recipes used in the studies and their results. Overall, the inclusion of LED inter-lighting with overhead HPS lighting boosted early production numbers in cucumbers, and small doses of far-red light with HPS lighting or LEDs benefited winter tomato and pepper production. Dynamic light recipes for long photoperiods (up to 24 hours) for greenhouse production of tomatoes, cucumbers, and peppers in the winter and microgreens in vertical farms were also identified. The next step is to incorporate the information gained from dynamic long photoperiod lighting research into dynamic lighting control programs to significantly reduce light fixture costs and energy costs.

INTRODUCTION

The impressive growth of Ontario’s vegetable greenhouse sector over the past decade or so

Top left: Pepper plants with poor architecture and fruit stacking. Top right: Pepper plants with short internodes.

would not have been possible without advancements in lighting research and technologies. More efficient light fixtures such as light-emitting diodes (LED) and new double-ended, high-pressure sodium (HPS) lights have allowed producers to be able to extend their vegetable growing seasons into the dark winter months in an economically sustainable way. The ability of LED lights to be adjusted to different light intensities and light spectral outputs was a game-changer.This allowed producers and researchers to experiment with different light recipes to optimize the light environment for their crops.

Before the commercialization of LED lights, HPS lights were used as only overhead lights for vegetable greenhouse production because the high operating temperature of HPS light bulbs did not allow them to be used close to the canopy. HPS lights also only provided one spectral output that was not adjustable. LED lights changed all that. The lower operating temperature of LED lights allowed them to be used not only as overhead lights, but also as inter-lighting within the canopy of vine crops like tomato, cucumber, and peppers. Also, by adjusting the spectral output of LEDs it became much easier to manipulate canopy architecture, and this allowed crops that were not able to grow well under HPS lights to grow under LED lights.

The difference in efficacy of light fixtures is another important consideration. LED lights are typically more efficacious than HPS lights (Table 1). The efficacy of fixtures when producing photosynthetically active radiation (PAR, 400-700 nm) is measured in the number of photons (µmols) per joule (J) of electricity it consumes. The higher the number of µmol per J for a fixture, the more light it produces per J, the more efficacious it is. The efficacy of HPS lights ranges from 0.9-1.8 µmol per J depending on the type, whereas the efficacy of LED lights typically ranges from 2.0-4.0 µmol per J.

But growing greenhouse vegetables in the winter using supplemental lighting is not as easy as flicking a switch. Growers need to adjust their cultivar selection, crop schedule, plant density, training systems, climate control, and irrigation schedules. The most obvious change is cropping schedule. Non-lit greenhouse vegetable production of high wire tomatoes, peppers, and cucumbers typically starts with planting around

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Tomatoes grown under HPS and far-red light. Researchers found that a low dose of supplemental far-red light achieved similar fruit yield as higher doses and used less electricity and had lower capital and instillation costs. (See: Tomatoes, HPS and farred light section of this article for more details)

December and January and harvesting ends around October and November for cleanout. Whereas growing these crops in the winter or for year-round production using supplemental lighting typically starts with planting around September and October and harvesting ends around July or August. In addition to changing the cropping schedule, the climate controls and irrigation schedules must be adjusted for winter production under lights to reflect the three periods with different light conditions when there is:

1. Natural daylight only or daylight plus artificial light

2. Artificial light only

3. Dark nighttime Irrigation should start when the supplemental lighting is turned on, which is typically a few hours before sunrise. Supplemental lights should be turned off around one hour before sunset to allow pollinating bees to return to their hives at this time, otherwise they might get disoriented by the artificial light. Cultivar selection also changes when growing with

TABLE 1

Typical energy input of light fixtures to achieve 220 µmol per m2 per second of PAR.

Mini cucumbers grown under LED inter-lighting. Growers can learn more about growing under this type of lighting in the section of this article entitled ‘Mini cucumbers, overhead HPS and inter-lighting LED lights.’

supplemental lighting. Many greenhouse vegetable cultivars that are suitable for non-lit production may not be suitable for winter production under supplemental lighting. The type of supplemental lighting also affects cultivar selection. For example, HPS lights may cause faster senescence in generative cultivars, while LED lights may delay fruit production in vigorous cultivars. When designing a lighting strategy for tall greenhouse vegetables, there are four main components that growers should think about:

1. What intensity of light should be used? This is usually called the photosynthetic photon flux density (PPFD) and it measures the amount of PAR light that plants are receiving in micromoles (µmol) per meter squared (m2) per second.

2. What photoperiod should I use? The photoperiod is the length of time that there is light whether it is sunlight or artificial light, and it is typically measured in hours. When you multiple the light intensity (in moles per m2 per hour) by the photoperiod (in hours) you get the daily light integral (DLI). This is the total accumulated amount of light that plants are receiving in one day measured in moles (mol) per m2 per day.

3. Which light spectrum should be used?

This is the light quality or light colour that is produced by the light fixtures measured in nanometers (nm). Broad spectrum white light typically covers the PAR spectrum (400-700 nm), blue light is 400-500 nm, green/yellow/ amber light is 500-600 nm, red light is 600-700 nm, and far-red light is 700800 nm.

4. What vertical distribution of light should be used? Lights can be used as top lighting above the canopy, inter-lighting within the canopy, or a combination of both. As mentioned earlier, HPS and LED lights can be used in different ways.

The general standard light intensity, photoperiod, and DLI values used today for winter production of high wire tomato, cucumber, and peppers are shown in Table 2. Please note that these values do vary with cultivar, local climate, and light fixture.

Since 2002, much of the lighting research that helped advance Ontario’s vegetable greenhouse industry was conducted by scientists at Agriculture and Agri-Food Canada’s Harrow Research and Development Centre in collaboration with other research institutions. This article aims to highlight and summarize a

few of the vegetable greenhouse lighting research conducted in Harrow over the past decade or so (2012-2022). Each of the sections below includes information that is specific to a different greenhouse crop (cucumbers, tomatoes, and peppers) and information about the light recipes used by the researchers and the results of the trials. The last section includes information about dynamic lighting research that was conducted on multiple crops (tomatoes, cucumbers, peppers, and microgreens). The dynamic lighting research will allow producers to truly take advantage of the flexibility in output offered by LED technology to reduce energy costs.

CUCUMBERS, OVERHEAD HPS, AND INTER-LIGHTING LED LIGHTS

Lighting Recipes: Some of the earliest vegetable lighting trials in Harrow were published by Hao et al. in 2012 and 2015. These trials were conducted on mini cucumbers. The first set of trials investigated combined HPS overhead lighting with LED inter-lighting systems. The crop was grown under 145 µmol per m2 per second of HPS overhead lighting in combination with 14.5 µmol per m2 per second of LED inter-lighting (10 per cent of top light). Red (660 nm), blue (460 nm) and white (broad spectrum 400-700 nm) inter-lighting fixtures were tested to determine the best colour. The photoperiod varied between 12 and 20 hours depending on natural light conditions. Supplemental lighting treatments increased as the crop aged, from 12 hours per day the week after the planting to 20 hours per day when a full canopy had developed. The inter-lighting was placed 60 cm above the raised trough close to the harvesting fruit.

The second set of trials focused on optimizing the combination of HPS overhead lighting and red/blue interlighting by testing different overhead intensities (120 and 165 µmol per m2 per second) and different intensities of interlighting (one or two rows of red/blue LED producing 36.7 µmol per m2 per second of light for each fixture). These trials also tested different planting densities (2.8 and 3.6 plants per m2) to determine if more or less plants affected the response to inter-lighting. The HPS top lights were placed three metres from the ground and the LED inter-lighting was placed at midheight of the crop canopy. When there

TABLE 2

Implementation of supplemental lighting in winter greenhouse vegetable production. * This is the total DLI (sunlight + supplemental light) normally used in commercial production to maintain good production. Higher DLIs may further increase yield but not necessarily higher profits because the additional yield gain may not justify the additional input costs. ** This is the total DLI to achieve the highest yield.

RIGHT

Cucumber plants are shown in a lowwire cucumber greenhouse that uses inter-lighting (combined HPS overhead lighting with LED inter-lighting systems).

were two inter-lighting modules included, one was placed about 60 cm above the bottom edge of the crop canopy and the other module was placed 40 cm above the bottom module. Together the two modules provided 73.4 µmol per m2 per second of red/blue light. The photoperiod varied between nine and 20 hours and the supplemental lighting treatments increased with crop age in a similar way to the first set of experiments. The supplemental lighting always ended just before sunset, the longer photoperiods were achieved by starting the lighting earlier in the night such as at 11:00 PM for the 18-hour photoperiod.

Results: In the first set of experiments, plants with blue LED inter-lighting were taller than plants with no inter-lighting under HPS overhead lights. Plants exposed to red and white LED interlighting treatments had more leaves than plant with no inter-lighting. Red, blue, and white LED inter-lighting all improved fruit visual quality and increased yield more than 10 per cent in early production. However, yield improvements associated with LED inter-lighting were not as significant during late production periods.

In the second set of experiments,

without HPS top lighting, single LED inter-lighting increased marketable fruit weight by 32 per cent over the control without any supplemental lighting. The combination of HPS overhead lights and LED inter-lighting once again increased yield and fruit quality over HPS overhead lights alone. In combination with the less intense HPS top lighting the double rows of LED inter-lighting increased marketable fruit weight by 42 per cent over the top lighting alone. The single LED interlighting and the more intense HPS top lighting increased marketable fruit weight by 10 per cent over the top lighting alone, and the mini cucumbers were greener. Best results with low intensity top lighting

TABLE 3

Daytime and nighttime light colour, intensity, and DLI for 16and 24-hour lighting treatments on peppers. All light intensity values were measured in µmol per m2 per second, and the DLI numbers were in mol per m2 per day.

and inter-lighting were realized when lower plant density was used. In contrast, higher plant density showed the best results with higher intensity top lighting and inter-lighting.

TOMATOES, HPS, AND FAR-RED LIGHT

Lighting Recipes: One of the first studies on far-red light in Harrow was published by Hao et al. in 2016. It investigated the effect of adding far-red light (725-750 nm) on tomato plants grown under HPS lights. Tomato plants grown under HPS lights with 165 µmol per m2 per second were provided with four far-red intensity treatments (0, 8, 16, and 24 µmol per m2 per second). The photoperiod started at 1:00 AM and lasted until 5:00 PM in December, 5:20 PM in January, 6:02 PM in February, and 7:10 PM in March. All lights were shut off when outside solar radiation was more than 300 W per m2

Results: Supplemental far-red light provided benefits in the early growth period during the winter when natural far-red light was low. The internode length and the chlorophyll content of young leaves increased with higher intensity of supplemental far-red light. Yield and size of the tomato plants also increased significantly, by as much as six per cent for marketable fruit, with far-red light treatments in the first month of the trial (January to February). Far-red light also changed the fruit quality by increasing total carotenoid content of the fruit. The benefits of far-red light, however, did not persist into the later growth periods in March when there was more natural far-red light. Overall, the low dose of far-red light (8 µmol per m2 per second) achieved similar fruit yield as the higher doses and used less electricity and had lower capital and installation costs. This intensity is lower than the far-red light intensity mentioned in the pepper section below because these HPS lights had about 10 per cent far-red light, or about 17 µmol per m2 per second, in addition to the far-red LED treatments. PEPPERS, HPS,

AND FAR-RED LIGHT

Lighting Recipes: Hao et al. (2019)

experiments on the effect of far-red light on bell pepper plants conducted between November, 2017-June, 2018. Plants were grown under 200 µmol per m2 per second of 1) HPS, 2) HPS and LED hybrid, 3) white LED, and 4) red/blue LED lights. An 18-hour photoperiod was used, and the lights were off when outside solar radiation was more than 300 W per m2. Each of these overhead light treatments also included 0, 26, or 52 µmol per m2 per second of far-red light. Without supplemental far-red light, the HPS lights already produced some far-red light whereas the LED lights did not.

Results: Pepper plants grown under white LED lights were the tallest (12-15 per cent more) and had the least amount of leaf chlorosis (73-90 per cent less). Those grown under red/blue LED lights were the shortest with moderate leaf chlorosis, whereas the plants grown under HPS lights had the most leaf chlorosis and moderate height, as compared to the other treatments. Adding far-red light increased the height of plants grown under all the lights by three-to-seven per cent, except the plants grown under white LED lights which were already tall. Far-red light also increased yield by 4-14 per cent under all lighting treatments, except for red/blue LED lights with the low far-red dose. Unlike tomatoes, these yield increases were observed in the later stages of winter production.

DYNAMIC, LONG PHOTOPERIOD, LOW INTENSITY

LIGHTING OF TOMATOES, MINI CUCUMBERS, PEPPERS, AND MICROGREENS

Yield increases from supplemental lighting are mostly determined by the added DLI, as summarized by the simplified Dutch saying

of “one per cent of light increase = one per cent yield increase.” The required DLI can be met over a shorter period of time with higher intensity lighting or a longer period of time with lower intensity lighting. Using a longer photoperiod with lower intensity lighting can significantly reduce light fixture costs in comparison to a shorter photoperiod and higher light intensity, because less lights would need to be installed. Furthermore, in regions such as Ontario with large fluctuations in electricity prices at different times of the day, longer photoperiods will allow much more flexibility to use cheaper electricity to meet the target DLI thereby significantly reducing electricity costs. However, plants have a biological clock and need “sleep”, just like humans. If the photoperiod is longer than certain thresholds, such as 16-17 hours for tomatoes, it will lead to leaf injury and yield reduction. This is known as photoperiod injury. In order to extend the photoperiod for greenhouse crops without photoperiod injury, we need to first find ways to overcome the crop’s biological clock to allow normal or better plant growth and development.

Therefore, in recent years the research in Harrow has focused on testing various lighting recipes under longer photoperiods (up to 24 hours) and reduced intensities of light to find ways to overcome photoperiod injury. This was done using dynamic lights that were able to produce different light spectrums at different intensities at different times of the day.

Tomato 24-hour dynamic light recipes and results: The first successful 24-hour light trial conducted by scientists in

New Construction & Retrofit

SOLUTIONS

Urban farm and greenhouse effort aids Calgary communities

Sixteen-acre industrial landscape finds new life as agricultural hub

BY JOHN DIETZ

A year-round greenhouse, without a foundation, is one highlight of social-and-environmental efforts to regenerate a damaged, 16-acre industrial landscape in Calgary into an urban farming hub.

It’s messy and it’s complicated, but that’s how life can be in a big-city, heavy-industry, zone. Highfield Regenerative Farm (HRF) is on “underutilized space” on the western heights of the Bow River Valley (highfieldfarm.ca).

Highfield Farm is on a high, rough, and torn piece of once open Prairie, about a kilometre east from the river, now surrounded by concrete, warehouses, and manufacturing. Neighbours are a major steel company, a motocross dragway, and

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Calgary’s high-traffic artery, Deerfoot Trail.

But, there’s a remnant of Prairie trees here and a desire for much more. The name captures the purpose: Highfield, Regenerative, Urban, Farm. Given success, one day it will be an urban refuge and landscaping icon.

UNDERUTILIZED LAND

Back in 2017, City of Calgary officials issued a call for proposals for the underutilized and degraded land. The farm was established in 2019. Today, in partnership with the City of Calgary and Compost Council of Canada, slow transformation is underway.

Highfield Farm was established in 2019 and its mission has been guided by three pillars: land revitalization, regenerative food production, and community building.

PHOTOS: JOHN DIETZ AND HIGHFIELD FARM

Selector RZ is the first ever winter type with High Resistance to Powdery Mildew. It is also High Resistant to CGMMV. The fruits have a great shape and are mainly in the medium grading. All of this without being sensative to low light necrosis.

Selector RZ

Long English Cucumber

• High resistance level against powdery mildew

• High resistance level against CGMMV

• No low light necrosis

• Well filled medium length fruits

• Planting period late November through January with no lights

For more information, contact: Cucumber Crop Specialist: John DeVries | (226) 936 1182 | j.devries@rijkzwaan.com For Ontario: RZH Canada Ltd | (519) 324 0632 For Quebec: Seminova / Agrocentre Fertibec Inc. | (450) 454 5155 For BC/Alberta: Terralink Horticulture Inc. | (604) 864-9044 For USA: Rijk Zwaan USA Inc. | (831) 455 3000

Sprung foundationfree greenhouse

Building a commercial-size greenhouse on site was a key component for long-term development, says Heather. It will extend the growing season at both ends by a month to six weeks, enabling significantly more production. It also could be used to generate revenue and hold classes.

Federal approval for a $227,000 grant to purchase and build a 4,800-square-foot greenhouse was announced in 2022 by Agriculture and Agri-Food Canada. The greenhouse is intended to support Calgary’s community-based local food system. It will enable Highfield Farm to expand Calgary’s usual short growing season to a year-round effort, supporting the goals of this local urban farming hub to provide Calgarians with fresh, locally-grown, nutrient-dense food while also providing an exciting community gathering place.

The rib-and-membrane, energy-efficient building is 40x120-feet and supplied by Sprung Structures of Aldersyde, Alberta. The aluminum substructure is rated to outperform steel; the tensioned and translucent architectural membrane has a longevity of approximately 15 years.

Still, if required, the rapidly built structure can be relocated to a second location in a few days. Aluminum doesn’t rust, and retensioning of the membrane panels is not required for the life of the structure.

City and federal stipulations are tied to the greenhouse.

Permanent buildings are prohibited on the urban farm. Instead of resting on a foundation, the greenhouse has a weather-resistant earth-anchor system. Each aluminum rib is attached to two duckbill-shaped anchors about 12-feet below ground. In turn, steel-cable in the ground connect the anchors.

“It’s a pretty solid system to hold this building down,” she says.

Sprung, founded in 1887 in Calgary, is one of Canada’s oldest family-owned companies. It has built more than 12,000 rib-and-membrane structures worldwide, resistant to hurricanes, sandstorms and blizzards. According to CEO Tim Sprung, the company only returned six years ago to building greenhouses.

A second stipulation, from the Local Food Infrastructure Fund, is that half of the space must be used for community gatherings and teaching.

“We turned the greenhouse on for the first time in April this year,” Heather says, after internal setup and city permits were completed. “Already we’ve seen a huge jump in our ability to extend our season and produce more. We won’t have an idea of the full impact of the greenhouse on our ability to produce until probably the end of next season.”

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Heather Ramshaw has been the operations manager at Highfield Regenerative Farm since 2021.

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The majority of food produced at Highfield is donated to organizations such as the Calgary Food Bank and the Mustard Seed.

Approximately 15,000 sq.-ft. of garden space is available. It has more than 900 members. The majority of food production is donated to organizations such as the Calgary Food Bank and the Mustard Seed.

Three “value” pillars guide the project: land revitalization, regenerative food production, and community building.

Much of Highfield Farm’s approach is based on education and involvement – offering extensive opportunities for volunteering and for experiential learning combined with environmental action like composting, soil health focus and crop selection.

This year (2023) as the HRF was getting ready to renew its five-year lease, it received a “Shared Footprints Award” from the Emerald Alberta Foundation. Presenting the award, Calgary said:

“The HRF strives to create a vibrant, creative and inspired urban community hub, centred around biodiverse land, regenerative local food, compost and soil health, education, and contributing meaningful work.”

NEW LIFE

In 2022, the farm attracted 637 individuals and approximately 1,400 hours of volunteer work. Other highlights included:

• Creating 7,048 yards of compost for use on-farm in 2022.

• Diverting 720 cubic yards of arborist/ landscaping waste from landfill sites.

• Helping community groups explore regenerative agriculture, composting and land revitalization.

Meet Heather Ramshaw, operations manager.

“I came from a community development background with a focus in food security and experience in organic farming,” she rattles off now.

Ramshaw came to 1920 Highfield Crescent SE, Calgary, in early 2021, after earning an environmental degree at the University of Waterloo. She found herself looking at a space of 79,000 square feet (about 850 feet square,) about the size of a long city block in each direction, without water, gas, or electricity, and with a 0.6 km walk to the closest transit stop.

Her farm’s founders, Mike Dorion, Jeremy Zoller, and Jay Fish were there for moral and administrative support as well as limited onsite labour. The three own and operate their own businesses today. They hired Heather to run the site year-

round, from an office trailer.

“One of the four original members stepped back in 2022 to pursue other opportunities, but Mike, Jeremy and Jay are here for the long haul,” Ramshaw says. “We are operating the farm on a hundredyear plan. Our primary five-year lease has an option to renew and, at the ten-year mark, if the city is happy and we’re happy, there should be no issue staying for the long term.”

For now, 16 activity areas have been identified and about eight groups

from surrounding communities have established special interest centres on the urban farm.

“Funding is probably the biggest struggle. It takes a lot of financial capital to make a project like this happen. Without having the large financial capital required to put in running water and power to the entire site, the missing infrastructure holds us back,” she says.

FUNDING

The water supply, for instance, is a fire

Winning mixes!

Mix Perlite Canada products to improve your soil

The HRF strives to create a vibrant, creative and inspired urban community hub.

hose attached to a nearby hydrant for the summer. It stretches across the site. It’s used daily to fill holding tanks to water the crops and operate an overhead sprinkler irrigation system. Gas and electricity are only available in her office and, on limited basis, in the greenhouse.

Cash flow comes from a few product sales, registration fees, memberships, donations, private grants and government grants.

“It’s always tough relying on grants,” she says. “We apply for grants from different levels of government. We have revenue from selling the mulch. We throw some events, and we charge for classes. It all helps.”

Fees range from free, allowing access to get your hands dirty and discounts on fees, to as much as $3,000 per year for companies, groups, or organizations to be actively involved in a healthy local food system and have large group access to a shared growing space.

Small groups of volunteers dot the farm daily, spring, summer and fall. Whole classes can be found there, learning gardening principles, in spring and fall. Tuesdays, the Compost Club shows up to turn about ten barrels of composting organic material. Every second or third week, all summer, groups are setting up and running special events like workshops with fees of $25 to $35 per person.

August events included Garden Club Saturdays, Alberta Open Farm Day, ABC Bees Field Day, Yoga on the Farm, Experience Metis Land Relationships, Farm-to-Table Dinner with The Basil Ranch Flower Tunnel, Seed-to-Table Fall Soil building, and the Compost Club Talk-and-Turn.

Across central and east Calgary, home calendars already were marked for the 2023 Soupalicious event on the first day of October. It’s become a popular, high-profile taste-off with soups built from the harvested produce plus vendors and music as a fall celebration.

Work on a farm is never done. Ramshaw says, “We have a great community that works hard to maintain the space, but we always need more folks coming out to do the hard labour. It’s never done.”

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One way Highfield generates funding is by hosting events and classes. Events like ‘Garden Club Saturday’ and groups like the ‘Compost Club’ keep the farm humming along, in addition to other sources of funding and grants.

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Highfield Farm is dependent on volunteers and community involvement. In 2022, the farm attracted 637 individuals and approximately 1,400 hours of volunteer work.

REDUCING nutrient inputs in mums

Modified strategy reduces costs, improves plant health

BY DR. BARRY J. SHELP, KATHERINE TEETER-WOOD, EDWARD J. FLAHERTY, LOU M. SCHENCK, AND JAMIE ALBERS

Chrysanthemums are an economically important floricultural crop worldwide. In Canada alone, approximately five-million indoor potted chrysanthemums were grown in 2020, making it the third most produced flower in the country. Indoor potted chrysanthemums are an excellent model ornamental crop for studying nutrient delivery because they are widely grown with closed sub-irrigation and drip-irrigation systems, which allow the recycling and reuse of nutrient-rich solution.

WHY WAS THIS STUDY CONDUCTED?

Plant growth increases with increasing tissue nutrient concentration until maximum growth is reached. At maximum growth, tissues can accumulate more nutrients and store them for future remobilization, but plant growth remains constant in this nutrient sufficiency zone. The sufficiency zone is large, so that the standard practice is to provide fertilizers so that the tissue nutrient concentration is in the upper range of this zone, which exceeds their requirements.

Many commercial fertilizer formulations (e.g., Peter’s Professional Peat-Lite Neutral Cal-Mag 17−3−17, ICL Fertilizers; Fusion Plant-Prod 17−5−17, Master Plant-Prod) are available for chrysanthemum production. They have similar macronutrient and micronutrient composition (in ppm): 285−300 N, nitrogen; 53−84 P, phosphorus; 285−300 K, potassium; 48–72 Ca, calcium; 17–22 Mg, magnesium; no S, sulphur; 0.75−0.83 Zn, zinc; 0.36−0.83 Cu, copper; 0.75−0.83 Mn, manganese; 0.1.50−1.68 Fe, iron; 0.34−0.36 B, boron; and, 0.15−0.26 Mo,

molybdenum.

Previously, our research group demonstrated that the supply of NPK to modern cultivars of indoor potted chrysanthemums can be reduced by approximately 75 per cent during the vegetative stage, compared to the commercial fertilizers, without compromising quality, and that it can be removed completely during the flowering stage. We also demonstrated that levels of the individual micronutrients can be similarly reduced. To validate this work, two similar experiments were conducted in a research setting using sub-irrigation and simultaneous reductions in essential macronutrients and micronutrients over the low sufficiency range during vegetative growth. Also, one experiment was conducted in a commercial setting using drip-irrigation.

WHAT ARE THE KEY FINDINGS?

The sub-irrigation experiments were replicated in a naturally lit research greenhouse during the summer 2022 and the summer/fall 2022 seasons using two cultivars (one cutting per 10 cm dia. pot). Nutrients were supplied to the 50:50 peat/perlite-based pot mixture via the use of a commercial peat Jiffy plug amended with 30 per cent minerals of unknown composition (Model CF Hort. Plug 343040, Jiffy Products (N.B.) Ltd., Shippagan,

FIGURE 1

Market-quality ‘Milton Dark Pink’ (top panel) and ‘Williamsburg Purple’ (middle panel) chrysanthemums were produced across the different nutrient regimens in a research setting.

PHOTOS: DR. BARRY SHELP ET AL.

NB, Canada); pH adjustment added Mg and Ca. Three rates of soluble nutrients were supplied during vegetative growth only, ranging from (in ppm): 75–150 N, 23–47 P, 103–205, 78–156 Ca, 11–21 Mg, 7–14 S, 0.15–0.29 Fe, 0.07–0.11 Mn, 0.06–0.11 Zn, 0.01–0.02 Cu, 0.01–0.03 B, and 0.01–0.02 Mo). Similar results were found with the cultivars ‘Milton Dark Pink’ and ‘Williamsburg Purple’ (Fig. 1). Results showed that the entire nutrient suite could be reduced during the vegetative stage by approximately 75 per cent, compared to commercial fertilizers, without any visible signs of nutrient deficiency. Furthermore, plant growth and quality were not substantially affected.

There were slight reductions in diagnostic leaf N (4−8 per cent), and as much as 20−23 per cent, 30 per cent and 40 per cent reductions in leaf B, Mn and Cu, respectively, across the two cultivars with decreasing nutrient supply in experiment 1, but no changes in these leaf nutrients in experiment 2. The leaf Mo increased by 30−40 per cent with decreasing supply in experiment 1 but was unaffected in experiment 2.

A single drip-irrigation experiment (experiment 3) was conducted in a commercial setting in the fall season 2022 using four cultivars (three cuttings per 15 cm diameter pot). Several nutrients (N, P, K, Ca, Mg, S, Fe) were added directly to the 90:10 peat/perlite-based pot mixture by a combination of custom nutrient pre-mixes and pH adjustment. Also, soluble nutrients were supplied over the low sufficiency range during vegetative growth only. A commercial fertilizer source with separate pre-mixed macro- and micro-nutrient bags was used so the exact mixture could not be as closely controlled as with the sub-irrigation experiments described above, resulting in similar N, P and K supplies, lower Mg and Ca supplies, and higher supplies of the micronutrients than in the sub-irrigation experiment. Sulphur was supplied directly to the pot medium only. The supply of soluble nutrients ranged from (ppm): 75–150 N, 22–44 P, 75–150 K, 13–26 Ca, 5–9 Mg, 0 S, 0.21–0.85 Fe, 0.11–0.43 Mn, 0.11–0.43 Zn, 0.11–0.43 Cu, 0.05–0.18 B, and 0.03–0.13 Mo). None of the cultivars (‘Milton Dark Pink’, ‘Springdale Purple’, ‘Olympia White’ and ‘Covington Yellow’) exhibited signs of nutrient deficiency or a consistent decreasing trend in shoot yield across the treatment range (Fig. 2).

conductivity in the pot leachate was reduced from 1516 to 361 ppm and from 3022 to 738 µS cm1, respectively with the decreasing nutrient supply. Replacement of the nutrient solutions with potable water decreased these levels within days to those present in the water.

Across cultivars, maximal losses in tissue N, P, K, Mo, Cu and Mn of the diagnostic leaf in response to the treatments were 18−23 per cent, 46–60 per cent, 32–36 per cent, 33–72 per cent, 33–42 per cent, and 35–44 per cent,

respectively. The other nutrients did not exhibit obvious decreases in tissue levels with decreasing nutrient supplies.

Across all cultivars, treatments and experiments, the leaf nutrient levels were: 4.91−6.60per cent DM N, 0.41−1.06 per cent DM P, 4.26−7.32 per cent K, 0.93−1.58 per cent DM Ca, 0.38−0.69 per cent DM Mg, 0.30−0.43 per cent DM S, 78−175 ppm Fe, 35−280 ppm Mn, 28−69 ppm Zn, 2.0−16 ppm Cu, 27−55 ppm B, and 0.5−22.8 ppm Mo. The nutrient levels in these three experiments generally

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Total dissolved solids and electrical

Market-quality ‘Milton Dark Pink’, ‘Olympic White’, Covington Yellow’, and Springdale Purple’ (from top to bottom rows) were produced across different nutrient regimens in a commercial setting.

aligned with established sufficiency levels provided by the Ontario Ministry of Agriculture, Food and Rural Affairs, (OMAFRA) in Publication 350 for chrysanthemum (4−6 per cent DM N, 0.2−1.2 per cent DM P, 1−10 per cent DM K, 0.5−4.6 per cent DM Ca, 0.1−1.5 per cent DM Mg, 20–750 ppm Fe, 25–375 ppm Mn, 5−35 ppm Zn, 5−50 ppm Cu, and 20−200 ppm B. Tissue sufficiency levels in the scientific literature for S and Mo in dicotyledonous plants are 0.25−0.70 per cent DM and 0.1–1.0 ppm, respectively.

Copper could be described as marginal in some cases, though Cu deficiency symptoms were not observed. Thus, the low nutrient inputs provided were sufficient to sustain maximal plant growth and could be considered to be in the low sufficiency zone, rather than in the deficiency zone.

IMPLICATIONS OF THESE FINDINGS FOR YOUR FARM OPERATION

Our modified nutrient delivery strategy was fully tested and validated with contrasting cultivars of chrysanthemum using both sub-irrigation and drip-irrigation. The nutrient supply was interrupted at bud break, and the macronutrient and micronutrient supplies were reduced by 77–82 per cent and 91–99 per cent, respectively, during vegetative growth, compared to common fertilizer formulations, without adversely affecting tissue nutrient levels and plant/flower quality. These findings suggest that none of the low nutrient regimens employed here limited growth processes. Thus, the common practice of delivering superfluous nutrient levels to greenhouse-grown chrysanthemum crops has little scientific merit. Furthermore, salt accumulation in the pot medium of dripirrigated plants was reduced by decreasing nutrient supplies. In closed drip-irrigation systems, plants are typically over-irrigated by 25−45 per cent to prevent salt accumulation, but optimizing nutrient delivery would minimize the need for over-irrigation and subsequent adjustment of the nutrient solution.

Adoption of our modified delivery strategy would reduce nutrient usage and production costs, the volume and nutrient level of the feedwater for treatment and/or approved discharge, and risks of salt damage to the crop and contamination of local waterways. Growers could consider reducing the amount of fertilizer applied to indoor potted chrysanthemum crops grown with sub-irrigation or drip-irrigation.

Barry Shelp is professor emeritus, and Katherine Teeter-Wood and Edward Flaherty are graduate students in the Department of Plant Agriculture at the University of Guelph. Lou Schenck is owner and operator of, and Jamie Aalbers is the trial manager at Schenck Farms and Greenhouses. For more information, please contact Dr. Shelp at 519-824-4120 ext. 53089, or bshelp@uoguelph.ca.

FIGURE 2

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Innovations in media amendments

Research out of Niagara College aims to minimize fertilizer loss in the greenhouse

BY CHRISTINE GEORGE

As the economic climate changes, growers find ways to adapt growing practices to reduce consumption of materials, and ultimately reduce costs. Substrates that growers use to produce healthy, marketable crops is varied - from rock, to peat, to even air. Add on to this the choices of fertility sources and growers’ crop decisions begin long before the seed germinates.

Traditional soilless media, whether it’s based in peat or coco coir, doesn’t naturally hold fertilizer nutrients well. Loss of nutrients through leaching or volatilization (gassing off) is an oftentimes accepted fact when growing a container crop (and in the field!). Any time fertilizer doesn’t make its way into the plant, it comes at a cost – be it out of the farmer’s wallet, or by negatively impacting the environment.

Niagara College’s Horticultural & Environmental Sciences Innovation Centre (HESIC) has recently been working with local businesses to help with this problem. The team has been examining ways,

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through using various growing media amendments, to minimize fertilizer loss in the greenhouse. Some of their findings show promise not only for the local businesses, but also for the agriculture community.

BIOCHAR

Biochar is one such amendment. Its origin use in agriculture is believed to date back more than 2000 years, in the Amazon basin. Nowadays, biochar is created through controlled burn (pyrolysis) of nutrient-rich, and previously unusable, biomass. The natural ability of biochar to hold nutrients and water appears to be a perfect fit in agriculture, but not all biochar is equal. Biochar can be created from different plant materials such as wood, straw, or food waste, and even animal waste. Depending on the original biomass source, biochar will bring different chemical and physical influences when used as an amendment. Therefore, any new biochar product should be tested before use to understand

Photo of student research assistant, Ashley Paling, monitoring crops grown in media amended with vermicompost and biochar at the Niagara College teaching greenhouse at the Daniel J. Patterson campus in Niagara-on-the-Lake.

PHOTO: NAGARA COLLEGE

what benefits, and possible deficits, will result in the growing media. If blended with fertilizers, the result of adding biochar to growing media could be even more valuable.

The HESIC team at Niagara College (NC) Research & Innovation (R&I), in partnership local businesses, has been studying biochar as an amendment to peat moss-based media. To be suitable as a media amendment, the biochar particles must be smaller than one centimetre in length – otherwise the media becomes too porous in container pots. The fertilizer also should be within this size range, which is why vermicompost works well.

Due to its high capacity for holding nutrients, the HESIC studies confirmed that the addition of biochar should be limited to no more than 20 per cent of the total media volume, particularly when biochar has been blended with fertilizer. At higher rates, the biochar can potentially hold too many nutrients, challenging the crop nutrient uptake. While researchers observed that biochar holds positively charged nutrients (cations) such as ammonium, iron and manganese, it may not affect the retention of some negatively charged nutrients (anions) such as nitrate and phosphate. While these observations are important to growers, the key question is: does biochar affect crop growth and quality? The answer is yes – multiple crops, from basil to strawberry – showed signs of higher quality with the presence of biochar in media.

ZEOLITE

Zeolite is another horticultural amendment being studied at NC R&I due to its capacity to capture and hold nutrients, in a similar way to biochar. However, zeolite is a porous mineral rock that is

mined from the earth, in Canada and around the world. There are many other industries harnessing zeolite’s natural properties – air purification, water filtration, animal feed, to name a few. Since 2019, the HESIC team has been studying zeolite in a series of projects funded by the Federal Economic Development Agency for Southern Ontario (FedDev Ontario) and International Zeolite Canada (IZ).

What the team has observed so far is that weight of the media increases when zeolite is blended in - a benefit when a crop such as hydrangea become top-heavy.

The HESIC team has been seeing promising results in their research on fertilizer-infused (or ‘pre-charged’) zeolite in a variety of crops and growing systems. They’ve documented that zeolite pre-charged with a complete nutrient package has the capacity to bring a hydroponics leafy green crop from seed to harvest, with no additional fertility required and in a potentially shorter time than is typically understood. It also has been seen to result in higher plant biomass than in a traditional hydroponics system. In addition, when pre-charged, zeolite is blended with greenhouse media, similar outcomes have been seen by the team. There is a lot more to learn when it comes to agricultural uses of zeolite, and IZ intends to continue supporting research in this area, so growers can understand how best to use this amendment.

Christine George is Research Lead at the Horticultural & Environmental Sciences Innovation Centre at Niagara College. To learn more about these and other research projects at R&I, visit our website at ncinnovation.ca.

SILICON NUTRITION of hydroponic crops

Element shown to have positive effect in mitigating plant stress, improving resistence

BY DR. MUHAMMAD TAHIR RASHID AND DR. MOHYUDDIN MIRZA

The second most abundant element on Earth is silicon (Si) after oxygen, and in many soil solutions (the liquid component surrounding plant roots) soluble Si is present, as silicic acid (H 4SiO 4) in roughly the same concentration as many of the mineral ions we consider important such as potassium and calcium. Plants are adapted to readily use this Si and it is possible for some species to accumulate levels up to 10 per cent of their dry matter.

Research has demonstrated that silicon is one of the most beneficial micro-elements for several plants. Silicon has not yet been considered as essential in plant nutrition, however, the essentiality of Si for plants has been the subject of a long debate dating back to the 19th century. However, its classification as a beneficial element has been recognized for more than 50 years and it is now reasonably well established that Si is essential for plants. Silicon mediates the acquisition, uptake, and translocation of nutrients including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, boron, chlorine, and nickel under both deficiency and excess conditions.

The past decade has seen a considerable increase in knowledge of the role of Si in plant biology and agriculture, as illustrated by the rapidly increasing number of both research and review articles (Jelena Pavlovic et al, 2021).

Additionally, Si ameliorates the vigour of plants and improves their resistance to exogenous stresses. The beneficial role of Si in plant nutrition is very well explained in this diagram (top right) adopted from Szilvia Kovács et al (2022).

Despite not being a common ingredient in hydroponic recipes, several beneficial effects of Si have been demonstrated in hydroponic systems. The use of Si as a nutrient in plants has shown a positive effect in mitigating environmental and pathogenic stresses. Increasing evidence in the literature shows that this metalloid is beneficial to plants, especially under stress conditions. Indeed, Si alleviates the toxic effects caused by abiotic stresses, e.g., salt stress, drought, and heavy metals etc.

WHAT COMMERCIAL FORMULATIONS ARE AVAILABLE FOR USE?

• Potassium silicate K2SiO3 has been available for longtime commonly called water or liquid glass. It is made by combining potassium hydroxide with silica and that is why it is a highly alkaline in nature. The water content may vary in different formulations. It has 50 per cent potassium, 18 per cent silicon and 31 per cent oxygen. This is important to know when we present a calculation on using silicon a part of the nutrient solution.

• Silamol® is a concentrated form of available liquid Potassium Silicate, which forms [Si(OH)4] upon dilution, approved for use on greenhouses crops and domestic potted plants, to alleviate abiotic stresses such as water deficiency, Cadmium, Manganese and Aluminium toxicity stress, as well as Phosphorous deficiency stress.

• Freshnaal is another source of silicon sprayed @100 ppm SiO2 on cereal, oilseed crops and fruits for anti-lodging, anti pod shattering, and shelf life, respectively.

• Some commercial soilless growing media are being promoted with silicon incorporated in them.

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Top: A cucumber plant that is NOT being treated with silicon. Bottom: A cucumber plant when silicon is being applied..

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LEFT

A diagram outlining the beneficial role the element Silicon plays in provindg nutirtion to some plants. Increasing evidence in the literature shows that this metalloid is beneficial to plants, especially under stress conditions.

USING POTASSIUM SILICATE AS PART OF FERTILIZER PROGRAM?

How to use these formulations of silicon is the most commonly asked question. Also, how frequently it should be applied. In the studies conducted by the authors, its frequency depends on crops being grown. For example, with seedless cucumbers we supplied 100 ppm of silicon dioxide from potassium silicate with every watering. Cucumbers is a “scooper” of silicon from the nutrient solution and has to be applied constantly. Major points to consider are:

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The past decade has seen a considerable increase in knowledge of the role of silcon in plant biology and agriculture, as illustrated by the rapidly increasing number of both research and review articles.

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This is the set-up of a cucumber grower using potassium silicate. Three injectors are used, one for calcium nitrate, second for NPK, Mg and trace elements and third for potassium silicate.

• Potassium silicate has a pH of >10 and thus should not be mixed with other nutrients in two stock tanks, that is calcium nitrate and all other nutrients tank.

• On the adjacent page, a set up from a cucumber grower is shown which uses potassium silicate. Three injectors are used, one for calcium nitrate, second for NPK, Mg and trace elements and third for potassium silicate.

• pH is adjusted in line and then all nutrients are mixed in the holding tank and then delivered to the plants.

• Some growers inject potassium silicate calculated at 100 ppm of SIO 2 and inject into the storage tank. From that point the high pH water goes into an injector which adjust the pH down to 6.0 and then other fertilizers are taken up in line.

ARE THERE ANY PLANT SIGNALS TO GUESS POSSIBLE SILICON DEFICIENCY?

Yes, the authors have noted some signals with cucumbers in greenhouses. Left: No silicon added, note the leaf is not erect as if no strength. Right: An erect leaf with proper expanded leaf. This was a case where a grower was feeding 100 ppm of SIO2 from potassium silicate and then ran out of it. Then started again feeding it and

leaves became erect again.

Cucumbers fruit also show white silicon deposit on their surface when plants have an adequate supply of silicon.

CONCLUDING REMARKS

The benefits of using silicon are well documented both in field and greenhouse crops. Growers can benefit by using it properly and regularly as part of their nutrient management program.

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ILLUMINATING IPM

Study offers further insight on the effect of LEDs on pests

BY REBEKAH HEST, DR. SARAH JANDRICIC, AND SOPHIE KROLIKOWSKI

Given the advancements in light technologies, many greenhouses across Canada are converting from conventional lighting to LED light. While the effects of light on crops have been heavily studied, it is important to also explore its effects on pests to update and implement more effective IPM strategies.

A previous article in this magazine has some interesting preliminary results on the effects of LED lights on thrips sticky card colour preference for mass trapping western flower thrips (see What does LED lighting mean for pest monitoring? By Sarah Jandricic, October 2021 edition). Today’s article takes a deeper dive into this question. Here, we explore how LED lighting affects catches of both thrips and fungus gnats, and demonstrate how results can differ depending on the time of year or the light recipe used.

Sticky cards or tape are considered an affordable IPM tool for thrips and other flying pests. These are generally blue or yellow because most insects are attracted to these wavelengths of light. But what happens when the lighting source shines different wavelengths on these cards? Is card colour preference affected?

To begin to understand the effect of light on perception, we conducted a series of trials to determine if sticky cards recommendations (colour, placement) should be changed based on the type of lighting used.

We used chrysanthemums as a model crop: they don’t need supplemental lighting, but they do host a variety of pests. 90 thrips per bench were released into the crop and allowed to reproduce for two weeks. The fungus gnats came free!

GREENHOUSE SET UP

lights from company 1 (80:20 red:blue – LED 1) and LED lights from company 2 (64:23:13 red:blue:green – LED 2) (see Figure 1 for light intensity, recipes and placement).

• Black-out curtains were hung between the benches and along walls shared with other greenhouse compartments to prevent interference from other lighting sources, with the exception of natural sunlight from above.

LIGHTING TRIALS

We chose to run two different trials at two times of year. The first was done under short days (eight hours of light) in January, when light levels are generally very low. Here, plants were grown under ambient light and supplemental light was given when needed. This reflects how growers are currently using supplemental light in an energy efficient way.

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Sticky cards under LED lights in a study looking at the effect of lighting on the behaviour of greenhouse pests.

• We set up our trials across two research greenhouse compartments at the Vineland Research and Innovation Centre

• Each compartment had three benches filled with vegetative chrysanthemum plants

• Benches received one of three treatments: HPS lights, LED

The second experiment was run in late February/early March. Here, we chose to go with ambient light with supplemental light for 24 hours of the day. Why? To try and kill several birds with one stone. Not only does this more closely mimic long-day ornamental production in the winter (~16 hours of light needed), but this also reflects ongoing research into 24-hour lighting

PHOTO:

1

Diagram of the lighting types used with light recipe, intensity and placement information.

regimes in vine crops with lower light intensity. From this point forward, the trials will simply be referred to as “Short Days” and “Long Days” for simplicity’s sake (see table 1 for details).

PEST MONITORING

Twelve pairs of yellow and blue sticky cards were placed both directly under the light (focal zone) and at a distance (bleed zone) on each bench and were collected at various time intervals. Depending on where the sticky card is placed underneath the light source, the colour may appear differently due to the angle of reflection. Most of the red/blue light is hitting on the side of the card in the more distant part of the light cone, so that’s where the

2

Diagram of experimental set up to account for effect of angle of reflection of light.

colour change is happening. (see Figure 2 for diagram of set up).

Thrips and gnats were counted at a later date and calculations were done to determine the proportion of insects caught on yellow cards versus blue cards under each treatment and at each card location (focal or bleed zone).

Lighting Trial “Short Days” “Long Days”

Period of trial January

Late February –early March

Amount of ambient light 11.3 mol·m-2·s 13.5 mol·m-2·s

Duration of supplemental light ~6.1 hours / day 24 hours / day

TABLE 1

Details of the lighting measurements taken between the trials.

RESULT – SHORT DAYS

After all the sticky cards were collected from the different lighting trials, what did we find?

Under HPS lights we saw the thrips behave similarly to previous experiments done under natural light conditions in summer. This was true for both card positions (see Figure 3(A)). Here, yellow is generally preferred over blue at a ratio of around 70:30. This makes sense, as HPS lights are full spectrum, and would more closely mimic sunlight.

However, the story was different under LED lights. Blue cards were preferred for both LED light recipes in the bleed zone (Figure 3, B and C). While there was still a preference of yellow under LED 1 in the focal zone (see Figure 4 for why this happens), light fixtures are generally set up to create as many areas of overlap as possible, to maximize lighting. Thus, the results in the bleed zone are more relevant to commercial greenhouses.

RESULTS – LONG DAYS

Here, we only focused on results with cards in the bleed zone, due to reasons explained above. HPS lights performed very similarly under long days as short days. However, to our surprise, the LED lights performed quite differently in this experiment.

The proportion of thrips attracted to cards placed under LED

FIGURE

FIGURE

3

Results for the “Short Days” lighting trial comparing lighting types, card placement and colour. An asterisk is used to represent a significant difference and blue boxes were used to highlight the bleed zone results.

2 suddenly skewed towards yellow, compared to the results captured under short days. Similarly, under LED 1, there was minimal difference between yellow and blue cards for long days (see Figure 5 – long day graph results graph), compared to the strong preference for blue that was seen under short days.

The differing strength of the results between the two LED types in this trial likely has to do with their light recipes. One recipe has more red (80:20 red:blue) and the other has less red and has the addition of green (64:23:13 red:blue:green). These differences in wavelength ratios likely affect how yellow and blue cards appear to thrips.

Additionally, we suspect that thrips attraction to yellow cards was generally stronger under long days, simply because this experiment was conducted later in the year. Although the difference between 11.3 mol-m-2∙s and 13.5 mol∙m-2∙s of ambient light might not seem like a huge difference, it could have been enough to “override” the effects of the LED lights that were previously seen under short days where the ambient light quality was low.

WHAT ABOUT THRIPS NUMBERS?

Knowing the preference of thrips for different traps under various

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FIGURE

FIGURE 4

Graph of the difference in percentage of light ratio hitting the side of the card depending on the placement under the light source.

lights is all well and good, but growers are also interested in lighting affects thrips numbers. We found that the proportion of the total thrips population was always highest under HPS lights, regardless of supplemental day length. Which is probably not surprising given the heat HPS lights give out (which can speed up thrips development and generation time). However, thrips could also be more attracted to HPS than the LED lights and have gone over or around our blackout curtains. This needs further testing, where heat is somehow controlled for.

5

Results for only the bleed zone for the “Long Days” lighting trial comparing lighting types and colour. An asterisk is used to represent a significant difference.

CONCLUSIONS AND TAKEAWAYS

We found under HPS lighting the thrips consistently preferred yellow over blue, so you know what to expect year-round. However, when using LED lights, the thrips response to sticky card colour seemed to depend on the time of year. In early winter, adding red and blue mixes to the light recipe skews the card preference towards blue for western lower thrips. But in late winter, around mid-February to early March, adding red and blue mixes showed yellow and blue are fairly equal.

Given these results, if the LED lights you’re using have a strong amount of red and blue in them (which is the usual case), then you may want to switch to blue cards from Late December to early March if western flower thrips are your main concern. However, fungus gnats preferred yellow cards under all test conditions, so be sure to stick with yellow if this is your main pest issue.

Our previous research has found that in early spring, ambient light conditions are bright enough so that LED lighting has no effect on thrips regular preference for yellow cards. The only exception to this is in highly overcast periods. Therefore, in late March, it’s best to switch to yellow cards, regardless of your supplemental lighting type.

In summer, thrips fly in from outside, so this is a critical period for mass trapping. Yellow cards should be used in all lighting conditions from April to October. Yellow cards also trap other pests like flying aphids, fungus gnats and whiteflies.

Lastly, if you are using a combination of HPS and LED lights in the same greenhouse (e.g. when switching over light types), you may see some hot spots of thrips under the HPS lights.

As always, with sticky cards, results can vary greatly depending on your greenhouse cover type and your location, as these both affect light quality. It’s always a good idea to test cards in a short, two-week trial in your facility, under your lights, and use your preferred brand of card to find out what’s best for you.

Rebekah Hest was a Research Assistant for the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) in 2022. Sophie Krolikowski is the Acting Maple, Tree Nut and Agroforestry Specialist at OMAFRA. And both were mentored by Sarah Jandricic, the Greenhouse Floriculture IPM Specialist.

FIGURE

Reap the rewards of energy efficiency

Tomato growers coming together

Three-day event brings international growers together to share experiences and to learn about greenhouse operations and growing under LEDs

BY KERSTIN POEHLMANN

Crop-specific community events bring growers from around the world together to not only learn from the operations they visit, but also from each other. Philips horticulture team has been hosting tomato community events annually since 2014 (the 2020 event was cancelled due to the pandemic, and the 2021 event was hosted virtually). One such event, hosted by the Philips LED team from Signify, was held in March of this year in North America and brought 49 tomato growers from 10 countries together, including Australia, Belgium, Canada, Czechia, Finland, Hungary, Japan, Latvia, the Netherlands, and the United Kingdom.

“Our customers are spread around the world, and each country has different ways to grow crops,” explains Ries Neuteboom, Canada Commercial

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Leader for Philips Horticulture LED Solutions. “We saw the opportunity to bring growers together to visit greenhouse operations, learn about the latest research, and exchange their experiences and knowledge among each other. The feedback is very positive year after year.”

This year’s event started out in the Leamington area of Canada. First stop was Great Lakes Greenhouses in Leamington, a 118-acre state-ofthe-art facility with year-round produce production including tomatoes, peppers, eggplant, and cucumbers. Over the years, 20 acres of their facilities have been equipped with Philips LED lighting in combination with GrowWise Control System to make the lighting dimmable. Unlike in Europe and other locations where growers mostly grow

In March 2023, 49 tomato growers from 10 countries, including Australia, Belgium, Canada, Czechia, Finland, Hungary, Japan, Latvia, the Netherlands, and the UK came together in Ontario.

PHOTOS: PHILIPS HORTICULTURE LIGHTING

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Attendees of the 2023 tomato community event in Ontario toured a number of greenhouses and operations to learn best practices for growing crops year-round under LED lights.

monoculture crops in glass greenhouses, attendees learned about multi-crop production in poly greenhouses.

Next up, the group visited Topline Produce, where the focus of the visit was on the company’s packaging and shipping methods. Aside from their own grown vegetables, Topline also markets produce grown by other growers. “Topline’s process is quite a bit different from how it’s commonly done in Europe, so this was a great opportunity for growers to pick up new ideas,” explains Kay Rauwerdink, global segment manager vegetables & fruits for the Philips LED team. “The fact that Topline grows, promotes and distributes its produce using a centralized model is unique to North America.”

From here, the group travelled to Mucci Farms in Kingsville, known as an industry behemoth which owns and operates over 250-acres of tomato, pepper, cucumber, eggplant, lettuce and strawberry greenhouses in Kingsville, Ontario and Huron, Ohio, and an additional global network of over 1,500 acres with partner growers. Since 2021, the 2.7-acre greenhouse visited on the tour has been equipped with a hybrid lighting solution of 50 per cent Philips Toplighting and 50 per cent High Pressure Sodium (HPS) lights, which was their first LED investment ever. Growers learned about their experiences with growing under LED and the reason for rotating tomato and cucumber crops, which is not standard practice in most other countries.

of automation in the entire propagation process; attendees were extremely impressed with the level of automation. LED lights play an instrumental role in their endeavour for consistent plant quality, as using LEDs reduces their energy use and is a workaround for limited availability of power.

The day was rounded out with a visit to Roelands Plant Farms in Lambton Shores, a premium propagator supplying vegetable growers across North America. Key in their rapid expansion over the past three-to-four years is their high level

Grodan-Ad-GROW-4.6875x4.75.pdf 1 6/23/23 12:24 PM

Seeing how these four operations use LED lights in their growing processes provided ample opportunity for growers to learn and exchange ideas. Finding the optimum in LED growing techniques was clearly top priority among attendees. It is still quite common for growers to use a hybrid model of HPS lights and LED lights in their operations. The energy balance emitted by HPS lighting is significantly different from that of LED lighting, and the high levels of radiant heat emitted by HPS lighting can stress or even burn the plants. With LED lighting growers can control heat and light separately meaning growers can apply higher levels of light to plants with 67 per cent less radiant heat than HPS lighting. A lower crop temperature means growers will have to raise the ambient temperature in the greenhouse and manage the related change in humidity. As attendees start to use

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One of the stops on the tomato community event tour in Ontario earlier this year was Topline Produce, where the focus of the visit was on the company’s packaging and shipping methods.

more and more LED lights, they welcomed the opportunity to learn how to adjust their growing strategy accordingly.

“I’ve been attending the tomato event for over five years now, and I’ve learned so much from other growers about how they manage their heat, for instance, about different ways of growing, and the best ways to utilize the LEDs,” stated one attendee from Finland. “Getting insights into different ways of working with the LEDs over the years has helped us also shape our own strategy,” added one of the attendees from the Netherlands.

The Philips LED community events develop and nurture close relationships between the growers, which continue much beyond the actual events. Growers tend to keep in touch and continue the idea exchange. Hearing what one grower does in one country can open the doors for new opportunities for a grower in another country. For instance, learning how growers in a country with low daylight levels like Finland successfully grow their crops might prompt a grower in another country to start growing a crop that they had previously thought could not be grown profitably under their climate conditions.

At the end of day one, the group travelled by bus to Niagara Falls, where

day two was kicked off with a morning of presentations and research updates presented by the Philips LED team. They discussed challenges growers are facing in the transition from growing with HPS via hybrid HPS/LED to growing with full LED, including humidity-management, balancing crop development versus integral pest management, and pollination challenges. Even genetics play a role, as research has shown that varieties respond differently to LED light/spectra treatments. In the afternoon, attendees had the opportunity to visit Niagara Falls before continuing by bus to Ithaca, New York.

Here, the Philips team works closely with researchers at Cornell University. Cornell is growing high-flavour cherry/ grape tomato varieties, including Vitalion, with intermediate Brown Rugose resistance, under hybrid and full LED lighting systems to track plant development, fruit quality, and yield. After a presentation on the wider perspective on greenhouse vegetable research by Professor Neil Mattson, Colin Brice – horticulture plant specialist for Philips LED team – presented the tomato trial results. “Hybrid and LED crops successfully managed to have similar crop development and production as well as fruit quality,” said Brice. “The results also showed the same yield in both 50/50 HPS

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Roly Holt, of R&L Holt Ltd. out of the U.K., was one of the attendees at the tomato community event in Ontario this year.

& LED vs full LED at 23 per cent reduction of lighting electricity costs by using LED lighting while running the greenhouse at 2 degrees warmer.” After the presentation, attendees visited the tomato LED trial at the Cornell research facilities, led by Nicholas Kaczmar of Cornell University.

“We learn so much about all the research knowledge that has been gathered when growing with LEDs. Especially the insights around the optimal light recipe and how to manage other factors in the greenhouse to optimize yield are so valuable,” stated one attendee from Latvia, while a grower from the Netherlands added: “When attending the tomato event, you always know you’re around other growers that think alike and use a similar level of technology to get the most out of their LEDs. It’s so inspiring to look around in France, the Netherlands, and this year in Canada and the U.S.”

It goes to show how great the cooperation is between growers, and how open they are to exchanging knowledge and ideas for the benefit and advancement of the entire industry.

Kerstin Poehlmann is president of Pen & Petal, Inc., a marketing communications firm for the green industry. She can be reached at kerstin@penandpetal.com

Grow with the pros

Amanda Hehr

Sunterra Farms Greenhouse, Alberta, Canada

“We wanted to maximize production and extend our strawberry growing season. Because the weather in Alberta is unpredictable, we installed a full Phillips LED solution for stable, reliable production through the bench months. Without the Philips lights, our strawberry production would dip substantially in winter. The Philips LED lighting team built an ROI model to ensure our investment pays back within three years; they are a partner in our success.”

Ho rt iculture LED

Harrow was published in 2019 (Lanoue et al., 2019). It examined tomato greenhouse production under 24 hours of supplemental lighting using alternating red light (200 µmol per m2 per second from 6:00 AM to 6:00 PM) and blue light (50 µmol per m2 per second from 6:00 PM to 6:00 AM). This was compared to a 12-hour lighting photoperiod with red and blue lights (red at 200 µmol per m2 per second plus blue at 50 µmol per m2 per second from 6:00 AM to 6:00 PM). Lighting was applied from November to May. The supplemental lighting remained on regardless of sunlight radiation levels to ensure that both treatments received the same total DLI.

Plants grown under 24-hour lighting grew in a similar manner to those under 12 hours of light, but they produced 12 per cent more leaf area and 10 per cent more stem fresh weight. Plants under both light recipes also produced similar numbers of fruit, but the fruit produced by plants grown under 24-hours light weighed 15 per cent more than the fruit produced by plants under the 12-hour light recipe.

ABOVE

Left: Tomato plants under and red and blue 12-hour photoperiod. Right: Tomato plants under a dynamic red and blue 24-hour photoperiod.

However, these differences were only seen in the early weeks of the experiment. Plants grown under both light recipes were similar later in the growing season.

Mini cucumber 24-hour dynamic lighting recipes and results: Another study published in 2021 by Lanoue et al. investigated production of minicucumbers under 24-hour lighting. There were four treatments:

1. 16 hours (6:00 AM to 10:00 PM) of red light (149 µmol per m2 per second) plus blue light (25 µmol per m2 per second)

2. 24 hours of red light (96 µmol per m2 per second) plus blue light (17 µmol

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per m2 per second)

3. 24 hours of alternating red light (151 µmol per m2 per second for 16 hours, 6:00 AM to 10:00 PM) followed by blue light (40 µmol per m2 per second for eight hours, 10:00 PM to 6:00 AM)

4. 24 hours of alternating between red light (210 µmol per m2 per second for 12 hours, 6:00 AM to 6:00 PM) followed by blue light (31 µmol per m2 per second for 12 hours, 6:00 PM to 6:00 AM).

All treatments had the same DLI of 10 mol per m2 per day. Lighting began in November and the lights remained on regardless of solar radiation to ensure all lighting treatments had the same DLI.

All plants grown under 24-hour lighting had higher chlorophyll content in their leaves compared to the 16hour photoperiod treatment, but no other differences in growth or yield were observed between the treatments. However, the 24-hour lighting regimes had an economic advantage over the shorter period of lighting in achieving the same DLI with less light fixtures and shifting some electricity demand to overnight hours when prices are typically low in Ontario.

Pepper 24-hour dynamic lighting recipes and results: A recent paper published in 2022 by Lanoue et al. investigated the use of far-red light in a 24-hour lighting recipe for bell pepper plants (Lanoue et al., 2022a). Five treatments were included:

1. 6 hours of white light (400-700 nm)

2. 24 hours of white light

3. 24 hours alternating between white light (for 16 hours) followed by blue light (400-500nm, for eight hours)

4. 24 hours alternating between white light (for 16 hours) followed by blue light and far-red light (700-800 nm for eight hours)

5. 24 hours alternating between white

light (for 16 hours) followed by far-red light (for eight hours)

Two experiments were conducted with the above treatments. The first experiment had a PAR DLI of 13 moles per m2 day and far-red DLI of 1.3-1.5 moles per m2 per day, and the second experiment had a PAR DLI of 10-11 mol per m2 per day and a far-red DLI of 1.0-1.1 mol per m2 per day (Table 3).

Fruit yield and fruit size was similar in all treatments, except for plants under 24 hours of white light that had lower fruit number and fruit weight than all other treatments. Both lighting treatments that included nighttime far-red light resulted in improved canopy architecture with 54-63 per cent taller plants and increased internode length, which prevented fruit stacking. This was observed consistently in early and late production periods.

Microgreen 24-hour dynamic lighting recipes and results: In another recent publication in 2022, Lanoue et al. investigated the effect of 24-hour white light on the growth of four types of microgreens: amaranth, collard greens, green basil, and purple basil (Lanoue et al., 2022b). These experiments were conducted in growth chambers, so they apply more to vertical farmers than greenhouse growers. Some seedlings were exposed to a DLI of 14-15 mol per m2 per day under 16 hours of light (251 µmol per m2 per second) or 24 hours of light (167 µmol per m2 per second), while other seedlings were exposed to a higher DLI of 21-22 mol per m2 per day under 16 hours of light (377 µmol per m2 per second) or 24 hours of light (248 µmol per m2 per second).

Increases in yield (fresh weight) were observed for all microgreens including a 93 per cent increase in amaranth, 46 per cent increase in purple basil, 43 per cent increase in green basil, and a 21 per cent yield increase in collard greens when the photoperiod was extended from 16 hours to 24 hours using the same light intensity. Food quality as measured by antioxidant, phenolic, anthocyanin, and chlorophyll content, was generally not affected or increased under 24 hours of lighting. Furthermore, the electricity cost per unit of fresh biomass was reduced by 8-38 per cent in all microgreens when they were grown under 24h lighting because some electricity demands were shifted from more expensive on-peak daytime hours to cheaper off-peak nighttime hours.

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INSIDE VIEW

GARY JONES | Gary.Jones@kpu.ca

When life gives you lemons…

If you’ve been part of the greenhouse industry for more than ten minutes, it will be no surprise that the two biggest costs by quite a margin are usually labour and energy. At least as you move further from the equator and spend significantly on energy for heating or cooling. Of course, the fundamental unit cost of each is (typically) always increasing. So, necessity being what it is, greenhouse businesses are always looking for ways to reduce the cost of energy input per unit of salable product.

With regards to energy, some things remain fundamental to making it all work. “During the June 2023 ‘Indoor Ag Tech Innovation’ event’…’Two panel discussions …addressed energy costs.’

• “You need to start by measuring and targeting the results of your best-performing crops and the bestperforming sections of your growing facility,” said Andreas Wilhelmsson, Chief Strategy Officer at Ljusgarda in Sweden.’

• “Get a good kilowatt per hour price from your energy supplier,” said Steve Marafiote, CEO of Sundrop Farms in Australia. “You should also look at any alternative options … or look for ways to produce your own green energy through solar or wind.”

businesses; and (if I can perhaps interpret the last statement) be a good grower.’ I think if you took nothing else away from that event, you’ll have already easily repaid your registration, travel, and attendance costs by having these five items presented at the same time in one easy package!

Probably if you’ve been around the industry for more than another ten minutes, you’ll also know that the speed of change and new technology seems to be ever increasing. It does seem to get more challenging to keep up. Which is a shame, because there are so many exciting technology things going on in the industry these days, with so much potential. For example, changes in lighting equipment enabling paradigm shifts in crop production cycles (e.g. to profitable all-year-round vine crop production); robotics, automation and autonomous growing; ideas around alternative energy sources; and, of course, urban agriculture and vertical indoor farming ventures.

Which means that on the face of it, there are wonderful opportunities for the industry to attract new people. People from outside our workspace who bring completely new skill sets and ways of seeing things. People not constrained by the idea that ‘we’ve always done it this way’.

“Measure your business performance to set baselines...”

• “You can’t improve on something you’re not measuring,” said Tisha Livingston, CEO of Infinite Acres, a subsidiary of Ohio-based 80 Acres Farms.

• “If you’re building new or renovating, engineer and design your facility to maximize energy efficiency right from the beginning” said Marcus Whately, CEO of Growup Farms in the U.K.

• “Do not ignore the power your plants have to manage their own energy use,” said Anthony Younan, Vertical Market Head, Industrial Americas at Siemens.””1

So, perhaps these gems can be summed up as ‘plan ahead, especially at the start; secure good prices of your energy inputs; look for alternatives; measure your business performance to set baselines; compare to the best performing

There’s a saying that ‘necessity is the mother of invention’. Perhaps energy issues are the gateway to helping us solve some of our labour problems. I don’t know really, and we’re perhaps talking about different kinds of labour issues. Perhaps I’m just being optimistic and joining dots that can’t be joined. Maybe I need to stick around for another ten minutes to see what happens.

1 Brian D. Sparks, ‘Five Insights on Energy Efficiency in Controlled-Environment Agriculture’, Greenhouse Grower, 16 August 2023.

Gary Jones sits on several greenhouse industry committees in BC and welcomes comments at greenhousewolf@gmail.com.

Our Field Application Engineers are experts in the design, installation, commissioning and troubleshooting of LED lighting solutions. Our team has the depth and experience to advise on mechanical installation, HVAC requirements and integration of control systems. And if you need on-site support, we can be there at your side. At Fluence, we want you to focus on your grow, and leave all your questions about lighting design to us.