Issue 5
Farm labour milestone
Ontario’s Seasonal Agricultural Workers Program (SAWP) is marking its golden anniversary this year. | 10
Editorial 4
Industry News 6
New Varieties 8
Business Issues 10 Seasonal Farm Workers Program’s 50th anniversary.
Technology Issues 12 Previewing Vineland’s new high-tech greenhouse complex.
Energy Management 18 Eyeing the many benefits of double screening.
Getting Energized 34 Waste heat capture among alternate energy projects.
Cara McCreary and Dr. Rose Labbé are studying how supplemental lighting affects greenhouse insects. | 22
38 Understanding the language of plants – Part 2 How cucumbers communicate when they’re hungry…or overfed
DR. MOHYUDDIN MIRZA
Year-round production at Harrow
Lighting among the ongoing studies in cover feature spotlight.
BY DAVE HARRISON
Weighing the many energy alternatives
We shouldn’t look for a silver bullet, one-size-fits-all solution.
BY GARY JONES
The Canadian greenhouse sector is maintaining its momentum. StatsCanada is reporting higher sales in virtually every category in 2015.
That’s great news, a major confidence-builder in an industry that’s long enjoyed growth across the board.
But after reading the report, we still have to wonder whether the results could be even better. And the short answer is, yes. Research will be the key.
The StatsCanada results are part of the annual Greenhouse, Nursery and Sod report compiled by Statistics Canada. (If we had any influence over the powers that be, we would ask that the report be focused on the greenhouse and nursery sectors only. We’re not sure why it also encompasses the sod sector.)
StatsCan says overall sales increased 3.3 per cent from 2014 to nearly $3.7 billion in 2015. Greenhouse products accounted for 76 per cent of all sales in this report. Greenhouse flowers and plant sales grew by 3.6 per cent, while sales of fruit and vegetables were up 2.9 per cent.
Ornamental product sales
due to lower prices.
Clearly the industry is doing quite well. The annual StatsCan reports for the past 20 years have been consistently – and equally – positive. Since the mid- to late- 1990s, the greenhouse sector has been the most buoyant of any sector in Canadian horticulture. Both ornamental and vegetable sectors have strong export markets, and that makes them rather unique.
Maintaining increased sales will depend largely on research, in finding new ways to grow increasingly energy efficient and labour efficient crops of premium quality.
Year-round production of greenhouse vegetables is an emerging trend. It’s a chance to win market share over the winter months. Consumers and retailers like the idea of yearround availability of locally grown vegetables. The Harrow Research and Development Centre is a world leader in this kind of research.
The Vineland Research and Innovation Centre is also studying alternative crops, and in particular
Annual reports for the past 20 years have been consistently positive.
(including greenhouse flowers and plants, nursery products and sod products) totalled $2.4 billion in 2015. Total greenhouse flowers and plant sales (including resales) rang in at $1.5 billion.
Greenhouse vegetable sales totalled $1.3 billion last year. (That’s about $300 million more than the value of field-grown vegetables.) Leading the increases was lettuce (up 13.4 per cent to $36 million) and peppers (up 6.9 per cent to $426.1 million). Tomatoes were up 1.9 per cent to $516.9 million. The only crop with reduced sales was cucumber, which dropped 1.3 per cent to $308.2 million – largely
exotic eggplant varieties not previously grown in Canada.
On the flower side, energy efficiency will be key. What crops, or indeed varieties, can be grown a little cooler and in shorter production times?
And there is a great need for increased automation to counter rising labour costs.
Science is the key to continued prosperity in the industry Researchers welcome grower feedback and ideas. Don’t be shy. Get involved, register for tours, and pass along suggestions on what needs to be developed and what needs to be improved.
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Whitefly is continuing to be one of the most difficult pests to control. Compounding the problem is that it has a very broad host range. There are not a lot of tools available to growers, but they’re far from defenceless. This month’s Greenhouse Canada Grower Day is offering a daylong series of presentations outlining what growers can do to control this pest threat. Also included is a mini trade show of leading industry suppliers.
Grower Day is June 15 at the St. Catharines Holiday Inn & Suites Conference Centre. Registration opens at 8:30 a.m., and the sessions begin at 9:15. Pre-registration is encouraged and easy to do on the Grower Day microsite at greenhousecanada.com/grower-day. Sponsors include Paul Boers Manufacturing, Prins Greenhouses, Dummen Orange, Vineland Research and Innovation Centre, Evergro and Greenhouse Canada.
Greenhouse growers may soon be tapping into new wastewater treatment systems.
Ottawa is providing a $400,000 investment with Flowers Canada (Ontario) to help with the testing of costeffective wastewater treatment systems. Developing and adapting on-farm waste water treatment systems is a top priority for the ornamental horticulture sector and this investment will help
growers minimize the amount of pollutants (nitrogen, phosphorus and solids) in runoff water. Experimental water treatment systems will be tested on four farms in the Lake Simcoe and Niagara peninsula regions to test for residual pollutants in runoff water.
This investment is being made through the Canadian Agricultural Adaptation Program (CAAP).
“This project
represents an incredible collaboration between the private sector and government, working together to promote environmental sustainability in ornamental horticulture,” said Andy Kuyvenhoven, president of Flowers Canada Growers Inc.
“Our members are engaged in developing new and innovative solutions for increasing water use efficiency on our farms. We are
very excited about the outcomes of this project and appreciate the support.”
Flowers Canada (Ontario) represents 250 provincial members, including distributors, importersexporters of cut flowers and potted plants.
In 2014, farm cash receipts of the ornamental horticulture sector were approximately $1.8 billion, with about $366 million in exports.
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CANADIANS SPENT 11% OF DISPOSABLE INCOME ON FOOD IN 2015.
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This is the first red angelonia – a huge colour breakthrough in this hard-working class! ‘Archangel Angelonia’ is best known for its large-size blooms and bold colour. It thrives in extreme heat, humidity and drought. Its uniform
Elevating the standards of size and quality in the De Ruiter pepper pipeline, Lemoncello is its new yellow, blocky pepper hybrid. With a high level of vigour, ideal generativity and large size, this variety produces good yield potential with higher fruit quality. www.deruiterseeds.com
habit and flowering time makes it easy for high-density production. The well-branched plants ship with less breakage, tangling and shrinkage.
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Dianthus Fruit Punch® ‘Maraschino’ has double crimson flowers with a prominent dark eye. Gardeners can expect good flower coverage with a compact habit. This plant has distinctive silvery-blue foliage in addition to good heat and humidity tolerance. It will reach 9-11” in height and will spread 12-14”. It’s hardy to Zone 4, and works well in full sun to light shade. www.provenwinners.com
Ducovery is De Ruiter’s newest tomato hybrid with an early high yield potential and Oidium (IR) resistance. This makes the variety suitable for the loose Beef growers. Fruit of
Ducovery are between 250-260 grams with strong vigour, and broad leaves that lay flat, making spray penetration easier.
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For more New Varieties, visit the “Marketplace” section at greenhousecanada.com. We’re always looking for New Varieties (100 to 125 words with high resolution photo) from breeders; please send to greenhouse@annexweb.com.
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Ontario’s Seasonal Agricultural Workers Program (SAWP) is marking a major milestone this year.
The program is celebrating its 50th anniversary supplying Ontario farmers experiencing domestic labour shortages with seasonal workers from Mexico and the Caribbean.
Approximately 17,000 seasonal workers from Mexico, Jamaica, Barbados, Trinidad/Tobago and the Eastern Caribbean States have been placed on Ontario fruit and vegetable farms this growing season as a supplement to local labour through SAWP, which is administered by Foreign Agricultural Resource Management Services (FARMS). Approximately 1,450 farms will benefit from the program this year.
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Anthony Cervini, representing the Ontario Greenhouse Vegetable Growers, has served on the FARMS board since 1990. He is also the president of CanAg Travel, the authorized travel agent for SAWP.
Cervini is with Apollo Farms and Lakeside Produce, two leading greenhouse operations in Leamington.
SAWP, he says, “has been the lifeblood of our industry. The greenhouse industry today across Ontario wouldn’t be where it is without the offshore program. There are not enough local workers available, especially during peak season.”
Like other greenhouse growers across the province, Apollo Farms and Lakeside Produce welcome many returning workers each year. “Growers like to get workers who have worked with them previously.”
One of Apollo’s veteran returnees, for example, has been with them for 27 years.
SAWP also works well for the offshore employees. “It provides a good income they can send back to their families,” says Cervini. “They have bought land and built homes and sent children through school with the money earned here. It’s definitely a win-win situation.”
The participating countries also benefit from the technology transfer of knowledge gained by those working in Canada. “There are many farms in the Caribbean and Mexico, but often not at the level of technology that we have here.”
SAWP got its start in 1966 when 263 seasonal workers from Jamaica were brought to Ontario to fill a shortage of available Canadian workers. Over the past 50 years the program has grown steadily and has consistently exceeded expectations, providing Ontario farmers a steady source of reliable, skilled and professional labour.
“Ontario produces some of the highest quality fruits and vegetables in the world. Without the supplemental labour they hire through SAWP, many of our growers just wouldn’t be able to stay viable,” says FARMS president Ken Forth.
At the same time, the program has given seasonal agricultural workers employment, benefits and educational opportunities not available to them at home.
Because SAWP is a “Canadians first” program, supplementary seasonal farm labour is hired from partner countries only if agricultural operators cannot find domestic workers to fill vacancies.
“Half a century after it was created, this program continues to serve the same vital function on an even larger scale,” says Forth.
A recent report by Agri-food Economic Systems found that chronic labour shortages continue to challenge the agricultural sector due to aging demographics, competition with other sectors and fewer numbers of young people pursuing careers in farming. As a result, demand for workers under SAWP is projected to remain steady.
The report cited the program as a key reason Ontario’s horticulture industry is able to generate $5.4 billion in economic activity and approximately 34,280 jobs.
It’s estimated that two jobs for Canadians are created in the agri-food industry for every seasonal agricultural worker employed through SAWP at Ontario farms.
More information about the program can be found at www.farmsontario.ca.
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Dr. Jim Brandle doesn’t buy into the adage, “If you build it, they will come.”
There has to be more to it than that.
“If you build it – and they need it – they will come,” the CEO of the Vineland Research and Innovation Centre says.
The proof is in the new pre-commercial greenhouse at the centre’s campus in Ontario’s Niagara region. Its 40,000 square feet of research space was built to commercial standards, and it’s where Vineland’s scientists are determining the best ways to advance greenhouse horticulture through breeding, improved plant performance and pest and disease management. It will also function as a testing ground for the development of robotics, automation and sensing technologies vital to the future of the industry.
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The official opening of the new greenhouse is June 3. Visit vinelandresearch.com for more information.
Large industry organizations are making the Vineland campus a destination to hold meetings. They’re keen to learn more about the good things happening under glass there when previously they might have gone elsewhere for inspiration.
“It is a flagship,” Brandle says. “It’s also emblematic of the rebirth of Vineland.”
The Vineland Research and Innovation Centre was established in 2007 to transform the former research station into a world-class horticulture research hub that would foster a vibrant and prosperous Canadian industry.
The greenhouse is the first major capital investment to happen at Vineland since the 1980s. It came to be after extensive consultations with greenhouse vegetable and flower growers, ensuring the creation of a facility that would meet their needs now and in the future.
It includes 13 compartments – two large-scale for vegetables and 11 for flowers or multi-purpose use – that will bridge the gap between innovation and commercialization. In fact, they already are.
“If you’ve been inside, you’ll see it’s impressive and it’s been full since the start, which means there’s a lot of pent-up demand for this space and the work happening there,” Brandle says.
The space replicates commercial greenhouses with its scale and infrastructure, including low-pressure sodium lighting in the flower sections, below-ground trenching to reduce shading, and total control of environmental variables, such as temperature, humidity and light. It has also been built to change with the industry; lighting was designed for future flexibility and options.
Most importantly, the greenhouse enables Vineland to emulate commercial scale production the same way it’s done in the industry. It’s also done under local growing conditions to better understand their impact on new varieties of plants and vegetables.
“A
“This will be a key catalyst to growing the industry,” Brandle explains. “The industry has reached a point where it needed to create that technology base – that new knowledge for our markets. You can’t import that so there’s great value in what’s produced there but also in the technology. This greenhouse lets us discover and evaluate things that are good for our region, specifically.”
How good?
As the largest pre-commercial horticulture research greenhouse in North America, this space will cultivate collaboration between industry and science, and drive economic growth. “This signals the future,” Brandle says. “It positions us to support a very successful industry to become more successful.”
This feature was prepared by Cheryl Lennox, director, marketing and communications, and Nathalie Dreifelds, advisor, communications and public relations, with the Vineland Research and Innovation Centre.
In this second of a two-part series, we learn some of the ways cucumbers communicate with us when they’re hungry or overfed…and even when they’re having to deal with chilly nights.
BY DR. MOHYUDDIN MIRZA
I view cucumbers as a fascinating crop to grow and to watch grow. With the arrival of mini cucumbers in the marketplace, I am finding the fruit harvest from seeding to maturity is even faster than regular Long English (LE) cucumbers.
For example a commercial grower shared the information that a crop of minis seeded on Jan. 21 of this year and transplanted on Feb. 10 had a first harvest that started on Feb. 27. This means the first harvest took place in 37 days from seeding during this part of the season. Supplemental light was used at an intensity of 12 moles/m2/day.
In the case of regular LE cucumbers, it took
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49 days during similar light conditions.
Because of its fast growing nature, the plant responds very quickly to become vegetative or generative to climate control, irrigation practices and stresses. In order to achieve above-average yields per square metre, one must understand the signals of plants.
There is no doubt that through the use of computers we gather a lot of data, but understanding the language of plants themselves is important.
Here are a few examples of what the plant is trying to tell us and after listening to it, what you can do to remedy the situation.
A cucumber crop in Alberta in early March, including (above) a close-up clearly showing an example of “elephant ear leaves.”
The pictures on the previous page were taken in early March. The lower photo is a close-up of a leaf. The plant had already reached the wire and was 60 days old. What it is displaying are “elephant ear leaves,” a vegetative signal by the plant. Look at leaves bending down and how the flowers are “weak.” It was another two weeks before the grower started the first picking. The plant is sending more assimilates to leaves compared to fruits.
Elephant ear leaves is an indication of a cooler night temperature that results in a lower 24-hour average temperature. In this case it was close to 18 C, while at this stage of growth it should be around 20.5 to 21 C.
It was recommended to increase the night temperature and bring the 24-hour average up. I am sure cucumber growers understand the strategies to deal with temperatures. There is average day temperature, average night temperature, temperature differential, pre-night and post-night temperatures, and how these temperatures are ramped up and down. These temperatures are adjusted based on daily light conditions.
This is an example of when a plant is trying to tell you that something is wrong with your temperature strategies. It was producing cucumbers nicely and suddenly leaves are coming out. Such leaves can come out on the stem end, blossom end or in the middle. This is a definite signal of the plant moving
from generative to vegetative growth. In Canada most of the nights are cooler and if a grower decided to turn the boiler off, they could expect such leafy growth from fruits of cucumbers.
The remedy to turn the direction around from vegetative to generative is to remove such fruit as soon as possible and then bring the 24-hour average temperature up.
In this case the cucumber plant was desperate to tell the grower something for several weeks. However, while the grower observed the symptoms, he or she was not able to do something about them. The grower was trying to develop organic protocols for cucumbers and could not find a suitable source of magnesium and potassium. “I am deficient in magnesium,” is what the plant is trying to say. “You see that my veins are green and my interveinal area is yellow. Pay attention to the edges of my leaves. That is potassium deficiency.”
So learn to diagnose nutritional problems and take action
early to reduce the misery and suffering of plants. A plant cannot make enough chlorophyll to manufacture its food if it is lacking in magnesium.
I would like you to notice three things in this picture. First is the light interveinal chlorosis, second is yellowing along
the edges, and third is that the leaves are standing upward with good strength on the petioles.
In the language of plants, this cucumber is trying to tell us the following:
• “That light chlorosis spread all across my surface shows you are loading me too much. I am trying to send as much food as possible to the fruits. That is my priority. Please help me to balance myself. Also, I would like you check my root
health as well. My oxygen levels are getting below 4 ppm and you know what it means to me. My roots cannot function properly and this fungus pythium is hanging around waiting to attack my hair where I absorb water and nutrients.”
• “My leaf edges are trying to tell you something. Do you know that I am ‘bleeding’ when you are not watching? My roots are telling me that you are giving me water and nutrients a little late. I am trying to shut my systems and you are still giving me plenty of water. I hope you know what I am talking about. This is my root pressure. I am trying to close my stomata because nighttime is coming and you are still supplying me with water. In case you don’t know, this bleeding is called ‘guttation’ in my language. If you don’t change your last watering to adjust to my need, this guttation will become serious and you know there is food in these water droplets. Vultures, such as botrytis, are hanging around. If they get their chance they are going to attack me and then you are going to take some action. I will not be able to give you those seven cucumbers per square metre per week.”
• “You know I like those strong leaf petioles of mine. When I compared myself with the leaves in the very first pictures, where the leaves are down, I would like to thank you because you have given me strength by using potassium silicate regularly. You recall that one day your pump got stuck and I did not get my dose of silicon, and you know what happened. Within two days, that darn white fungus was all over my leaves! My food manufacturing capacity was reduced by 50 per cent. I was really suffering but I am glad you noticed it quickly and fixed the pump. My food manufacturing capacity is back. In case you need to know what I am talking about, here is the picture (at right) you took.”
Reading a plant should be a dedicated task on a daily basis. Grab your camera, walk through the crop, and find out what plants are trying to tell you!
Dr. Mohyuddin Mirza is an industry consultant. He can be contacted at drmizaconsultants@gmail.com.
It’s the right formula for success at Ontario’s NatureFresh Farms, offering an optimal summer growth climate along with added energy savings in winter.
BY JOLI A. HOHENSTEIN
Weary of yearly whitewashing to protect their peppers from sunburn, Ontario’s NatureFresh™ Farms went in search of a more efficient option. They found the answer in double screening, a technique that European growers have been using with great success for years, but which is still relatively new to North America.
After a side-by-side trial comparing double screening in one six-hectare section to another section with standard whitewashing, the results were so compelling that they’re currently installing the system on another six hectares, with the potential for more.
“Right away we noticed plant temperatures and greenhouse temperatures with double screening were cooler compared to the other section,” says head grower Herman Fehr.
Plant temperature is vital for NatureFresh, one of the largest greenhouse pepper growers in North America. At their Leamington location
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alone, they’re operating 12 hectares of glasshouse producing green, red, orange and yellow peppers.
But until the double curtain installation in early 2015, they weren’t using light effectively, and Fehr’s suspicion was that they could be getting more from their plants.
He was right.
“With this system our plants are growing more generative – and we’re not afraid of sunburned peppers,” he explains. “The idea was to only shade when the sun is at its strongest peaks, and not on cloudy days.”
The double curtain system NatureFresh is using combines Svensson’s Harmony open light diffusing shade and Luxous translucent energy savings screen.
During the cold Leamington winters, when temperatures commonly drop to -12 C, the transparent Luxous screen ensures a reasonable energy input and an ideal microclimate for
Inspecting pepper plants’ response to double screening at NatureFresh™ Farms.
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plants. The screen is closed throughout the night and often during much of the day. NatureFresh typically opens it at sun radiation levels of 300-400 W/m2 on cold winter days. The “clear as glass” property of the Luxous energy screen allows for daytime usage.
Home to temperature extremes at both ends of the scale, Leamington pairs very cold winters with spring and summer days that are often hot and sun-intense, necessitating protection for pepper crops to prevent plant temperatures from reaching too high.
NatureFresh™
Farms is one of the largest independent greenhouse produce growers in Canada and one of the largest greenhouse pepper growers in North America.
evening and on cloudy days,” says Fehr.
The process comes with limitations, he explains. It has to be at least 10 C outside to be able to apply the coating on the roof – and that doesn’t come very often in March in Leamington.
“In March we have very bright days, and we can’t close the energy screen because it doesn’t have enough airflow,” Fehr says. “We can utilize this system a bit earlier than you can a whitewash.”
To solve this challenge, NatureFresh chose an open light diffusing Harmony shade that provides 25 per cent shading in direct light while also offering a high degree of diffused light in the greenhouse.
In the portion of the glasshouse without the double curtain system, operations went on as usual. “Every year we were applying a light diffusing coating on the glass and losing light in the morning and
The NatureFresh trial has debunked conventional wisdom on several levels. While not proven, the perception was that whitewashing was more effective than using a shade screen. But this fixed solution has its limitations. For example, if two weeks of cloudy days follow after painting, it’s not efficient to remove the coating to get more light. “So, you’re sacrificing extra yield with a fixed coating solution,” says Svensson’s Mauricio Manotas.
NatureFresh compared the climate in the double screened section to another section of the same greenhouse equipped with light-diffusive paint on the roof and no shade screen installed. They found that during summer days in the section with the mobile Harmony screen, the crop received more cumulative light and temperatures were lower.
“On hot sunny days, plants were about two degrees cooler with Harmony,” says Fehr. “We were very impressed that we were able to keep a lower plant temperature.”
Fehr was also very pleased that the light-diffusing screen could be fully closed, shielding the entire crop from intense sun radiation. “We feared there would not be enough air exchange but that wasn’t a problem,” he says.
Another unexpected benefit: the ability to close both screens, which resulted in 4 C lower pipe temperatures compared to the reference section that was equipped with only the energy screen.
Says Manotas: “The bottom line is, you can have the same cooling effect using a shade screen that you can with whitewash – plus you receive several hours of extra light each day.”
Joli A. Hohenstein is a marketing and PR specialist for Pen & Petal, Inc., a marketing, advertising and public relations agency for the green industry. She can be reached at joli@penandpetal.com or 217454-0542.
Greenhouses have always had the environment to permit four-season growing, but winter light levels in Canada have been the main limiting factor. Until now.
BY DAVE HARRISON
The Harrow Research and Development Centre is busily working to illuminate important new winter markets for Canadian greenhouse vegetable producers, all thanks to its year-round production initiatives.
Winter crops would fill store shelves with locally grown tomatoes, cucumbers and peppers, allowing retailers to have a single year-round source of these vegetables.
The greenhouses have always had the environment to permit four-season growing, but winter light levels in Canada were the main limiting factor. However, work by Harrow research teams is fine-tuning the necessary supplemental light
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recipes for winter crops.
The results have been quite impressive, as we learned on a recent tour of the AgCanada facility located within minutes of North America’s largest concentration of greenhouse vegetable production. The yearround production project is a fiveyear effort that will wrap up in 2018.
We spent a day in early April touring the Harrow facility to view some of its latest projects, a tradition at the magazine that goes back some 15 years or so. It’s a great opportunity to provide an overview of some of the studies underway.
In addition to year-round vegetable production, we also viewed some strawberry trials. There is
OMAFRA’S Cara McCreary and AgCanada’s Dr. Rose Labbé are working on a number of lighting trials and the effect on greenhouse insects.
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Shalin Khosla looks over a Harrow greenhouse strawberry trial – commercial production in Ontario is increasing each year; Dr. Xiuming Hao is studying blue and red intra-crop LED lighting effects; strawberry trials at AAFC’s Harrow Research and Development Centre.
growing interest in the crop, and Harrow is determining the best varieties and treatments to make it commercially viable.
(My tour timing was a little off. I had just missed strawberry harvesting by a day or two. How much better could an early April visit to Harrow be than with a sampling of ripe, fresh strawberries!)
Our visit also included an update on the growth of the Ontario industry, and a look at trends.
Great strides are being made into costeffective year-round greenhouse vegetable production, and Harrow is at the forefront of Canadian studies.
The greenhouse team is about halfway through a five-year research program that will conclude in 2018. Dr. Xiuming Hao is heading the group.
Canadian retailers are increasingly looking to year-round sources of locally grown vegetables. Greenhouses with supplemental lighting will allow growers to meet the demand, says Hao.
“Year-round production is important for growers to increase their market share. Lighting is a big trend for the industry.”
He and his colleagues have done considerable work already with lighting and extending the season.
From 2004 to 2008 they focused on year-round English cucumber and mini-cucumber production, and with impressive results. Using HPS (high pressure sodium) lights, they increased annual cucumber yields by 100 to 150 per cent in comparison to unlit conventional systems.
From 2009 to 2013, they worked with hybrid lighting systems of overhead HPS lights and intra-canopy LED lights to create a vertical lighting strategy. Unlike HPS lamps that give off heat, LED bulbs are cool and can be placed very close to the plants. The hybrid lighting systems using the two lighting systems ensure optimal and uniform lighting throughout the vertical crop canopy. The LEDs allow the plant to maintain its vigour, resulting in higher late season fruit yield in comparison to use of HPS lighting only.
Harrow researchers this year are looking at year-round pepper production, and preliminary results are quite encouraging.
It’s important for growers to know that when they go into year-round production with supplemental lighting, it will mean different cultivars, and different climate control and nutrient management strategies.
In the current trial, three cultivars were evaluated and one in particular stood out. “The choice of cultivar in year-round production makes a big difference,” Hao explains.
Because light fixtures represent such a large capital investment, it’s more costeffective to use them for longer periods of time. Some varieties respond to the extended photoperiod much better than others.
The key is to use lights for longer periods of time and have the plant respond accordingly – without triggering leaf chlorosis – to improve fruit yields and quality. (Leaf chlorosis can result if the photoperiod is pushed beyond the cultivar’s limit.)
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Dr. Xiuming Hao looks up at this six-month-old pepper crop grown under lights; assay of predator establishment on winter pepper and tomato crops under blue LED lighting; AAFC’s Harrow research centre is a world leader in greenhouse vegetable lighting trials.
Hao’s group has developed Dynamic Temperature Integration (TI) strategies with a pre-night temperature drop to improve the response of greenhouse tomatoes and sweet peppers to long photoperiods of lighting. The drop creates a difference in temperature between the leaves and the fruit.
“You have to be careful to only drop the temperature to a level that the crop can tolerate,” Hao emphasizes. The lower temperature is only allowed for about a half hour or so. With tomatoes, for example, you can drop the temperature to 14 C to 15 C before returning to 18 C. For peppers, you can’t go below 15.5 C to 16 C.
It’s also important that daytime adjustments are made to maintain the same 24-hour average temperature setting.
During the temperature drop, the larger surface area of the leaf means it will get colder faster. However the fruit, because of its larger volume, will lose its heat much slower and remain a few degrees warmer than the leaves. This changes the plant growth balance in
favour of the fruit, resulting in accelerated fruit growth, substantially reduced leaf chlorosis, and increased total yields.
The pepper trials are off to a good start. At the time of our visit, the crop had been growing for six months. Hao estimates the six-month crop has already matched – or is close to matching – the annual yields of a traditional pepper greenhouse (25-30 kilograms per square metre).
He hopes to achieve 45 to 50 kg/m2 of peppers in a 12-month crop trial.
Hao showed me a stem with nine fruit on it. Each pepper was about 250 grams. The crop had grown to 2.5 to three metres tall in only six months. “Growers who have stopped by to visit have been quite impressed.”
The system needs the right cultivar, along with the right climate control, heating and nutrient management strategies to be effective. As well, it needs a pruning strategy that provides a larger canopy to intercept light.
Last year’s work with mini-cucumbers had yields of 62 to 65 kg/m2 over six months. Add to that a summer crop of
about 50 kg/m2, and the total yield would be about 110 kg/m2
By comparison, a commercial mini cucumber greenhouse will have four crops per year, and each will produce about 15 kg/m2, resulting in a total yield of about 60 kg/m2
Supplementary lighting, then, will almost double the yields and reduce the number of crops from four to two. “We also have seen very little disease,” says Hao. The crop has been growing for six months with no powdery mildew.
In another trial with mini-cucumbers, Far-red LED lighting and HPS lighting are being studied. With HPS lighting alone, the leaves tend to be a little smaller because of the infra-red heat. The Far-red light, on the other hand, could result in larger leaves to intercept more light.
You only need a small dose of Farred light on the top of the crop. This light signals to the plant that it is being shaded, and the leaves will stretch.
“This will mean faster growth in the early stages,” says Hao. “The stems will be longer and the leaves will be bigger.”
In 2014-15, similar trials were conducted with tomatoes. The results were higher early yields because the taller plants and larger leaves intercepted more light.
This year’s mini-cucumber trials look just as promising, though the results had not been analyzed at the time of my early April visit.
Hao and his colleagues are also looking at LED lighting with tomatoes.
The big advantage with LED lighting is its narrow spectrum and you can really optimize the light quality. HPS has a fixed spectrum, however, and can’t be changed.
Far-red light will make leaves bigger, and blue light will make leaves thicker though average size. This knowledge can be applied at different crop stages to optimize leaf and fruit growth. Growers can apply different lighting recipes for different growth stages.
Blue light also promotes development of antioxidants.
As an example, the Plant Factory in Japan provides red light for the first 20 days of its lettuce crop for larger leaf development. However, they switch to blue light for the final three days to improve antioxidant and pigmentation levels.
With the current LED trials at Harrow, Far-red light is applied overhead, while blue light is placed within the canopy to promote fruit quality and antioxidants.
More premium grade tomatoes are produced with blue light in the canopy.
As well, blue light has been found to produce more antioxidants in mini-cucumbers.
“We need to find the optimal vertical lighting recipes for the top and bottom/fruit of the crop,” says Hao, who adds that nutritional management will also need to be adjusted to match the growth of the plants.
These lighting trials are being funded by the AAFC; the AgriInnovation Programs of Growing Forward 2 from AAFC; and by the Ontario Greenhouse Vegetable Growers.
Hao is also leading a new three-year LED research project funded by AAFC. It will look at LED applications in all three major greenhouse crops – tomatoes, peppers and cucumbers.
Hao will focus on the physiology, yields and fruit quality aspects of the trials.
Others team members include:
• Dr. Rose Labbé, entomologist at Harrow Research Centre, will study the effect of lighting on greenhouse biocontrols and pests.
• Dr. Aiming Wong, of London Research Centre, will study how LEDs might be applied to greenhouse vegetable crops to increase plant tolerance or resistance to viruses and diseases.
• Dr. Rong Cao, of Guelph Research Centre, is a specialist in nutritional values of food. He will look at how LEDs affect the nutritional value and antioxidant levels of greenhouse vegetables.
• Dr. Bernie Grodzinski, a professor at the University of Guelph, will look at how LEDs can speed up the translocation of photo-assimilates from the leaves to the fruit to increase yields.
Entomologist Dr. Rose Labbé is the newest member of the greenhouse team at the Harrow Research and Development Centre, arriving in July 2015.
The greenhouse industry is expanding its year-round production capabilities, and that requires supplemental lighting during the winter. Considerable work on year-round production is being carried out at Harrow. Labbé’s work with pests and beneficials will dovetail quite nicely with work being done by colleague Dr. Xiuming Hao on crop production systems.
Hao has a number of lighting systems, including LEDs, set up for his trials.
“We are incorporating some of our research to see whether biocontrols might be establishing better under the lights,” Labbé explains.
Her team is using a combination of lab trials to study basic behaviour, development times, fecundity rates, and longevity
of some of the most common generalist predators, including Orius and Dicyphus.
They will also look at the potential of using supplemental LED lighting to break the diapause stage of a number of key predators, including Orius, Dicyphus and Feltiella.
The work is currently focusing on a small spectrum of blue and red light, and will be looking at other spectra going forward. The work will be important not only to growers, but also to biocontrol companies looking to establish
1populations of these predators in the winter months.
Labbé is also studying the establishment of predators under a variety of lighting conditions. Preliminary results suggest that relative to untreated compartments, establishment of the predators was much better under lights. Dicyphus responded especially well – two to three times better – under both the HPS and LED light treatments, compared to the compartments without lights.
“That’s pretty impressive,” notes
Labbé. “We will be repeating the trials in a commercial setting.”
Work has been done with Orius in experimental greenhouses. It did very well under the lights, with about a 20 per cent increase in establishment rates.
These preliminary results suggest that lighting in general will help predators get established in early season. Predators tended to live a bit longer and were reproducing earlier under the lights.
Labbé is also conducting predator mite trials, continuing some of the work started by Dr. Les Shipp before he retired a few years ago.
Greenhouse Canada’s annual search for young industry leaders is again underway! Canada is full of young, skilled knowledgeable people helping to drive the industry towards higher goals. From commercial growers and wholesalers to manufacturers, equipment suppliers and allied trades, they are the best and the brightest in our industry. Join us as we celebrate the future of greenhouse horticulture in Canada.
Anyone in the horticulture or associated industries who is under the age of 40 as of December 31, 2016. Equipment and technology suppliers welcome.
all nominees should:
• demonstrate a strong work ethic
• show leadership and initiative
• actively seek new opportunities for training and education
• be involved in industry associations
To nominate someone to be recognized as one of the Top 10 Under 40, visit greenhousecanada.com/top-10-under-40 to fill out a nomination form. Nominations close on August 26th, 2016.
One of the promising new hopefuls is Typhlodromips montdorensis, which is not yet registered in Canada. It doesn’t restrict itself to thrips, the target pest in the trials.
Typhlodromips is said to be fairly competitive with other mites in the early season. Labbé’s results, however, are very preliminary as they are only about halfway through the trials.
Another project is looking at the effect of blinking LED lights on nocturnal pests. The lights seem to be a deterrent to the unwanted visitors. “Any pests that are typically nocturnal would be susceptible to this kind of technology,” says Labbé. “It’s quite cutting edge.”
AgCanada is continually assessing the potential of new pest threats. The goal is to pre-empt their arrival by looking at new control measures, including finding new parasitoids that could be deployed.
Labbé is also part of an AAFC working group developing procedures to assist the Canadian Food Inspection Agency (CFIA) in testing for non-targeted impacts of new biocontrols being assessed during registration submissions. The goal is to have a methodology to help potential applicants in moving their product through the process. “This will be a big help to the industry in general in accessing new biocontrols.”
Greenhouse construction crews were again busy in Ontario in 2015, with acreage increasing by five per cent to 2,800 in total.
During our recent visit to the Leamington/Kingsville area, it seemed as if every concession was home to at least one construction project. Quite impressive! Expansion has become business as usual in this vibrant region, home to North America’s largest
concentration of greenhouse vegetable production.
OMAFRA greenhouse vegetable extension specialists Shalin Khosla (crop production) and Cara McCreary (IPM) work closely with the AgCanada researchers on projects. They have offices at the Harrow centre.
Khosla says there have been a number of changes in the industry over the past few years.
• First, there are more high-tech glass greenhouses being used in construction, and more growers are looking at diffused glass. As well, there is considerable interest in energy curtains, with at least one curtain – and sometimes two – being installed.
“The price of glass has come down dramatically and the price of plastic has gone up,” Khosla explains.
Growers who have moved to glass have learned to operate under it and are able to optimize their production, resulting in impressive yields. “That’s an incentive to other growers to consider glass.”
As well, double poly has to be changed every three to four years, and there are now fewer people able to do it because of the rising heights of new greenhouses.
• Secondly, there has been a change in the crop ratio. In the past, peppers were third after tomatoes and cucumbers in terms of acreage. However, peppers have now edged their way into second place.
Organic production has been increasing, driven by consumer and retailer demand. Just about every major packing house in Ontario has some organic product lines, including tomatoes, cucumbers, peppers and lettuce.
A wide variety of specialty tomatoes, along with mini peppers and cucumbers, are also grown.
There is growing interest in lettuce, and more recently in strawberries. Of the latter, Harrow has been conducting trials the past year and with good results.
Greenhouse strawberries are fairly common in Europe, but the Ontario industry would need North American cultivars and that requires the development of a specialized knowledge base geared to local conditions.
The interest in greenhouse strawberries is deeply rooted in the
Ontario industry, as Khosla recalls trials conducted about 26 years ago at Harrow!
The current research has included HPS and LED lighting systems. They’ve been looking at three growing media – rockwool, BVB (a soilless mix) and capillary mats – and two cultivars (‘San Andreas’ and ‘Albion’).
On the heating front, a number of growers have switched from steam to hot water. There are benefits with both, says Khosla, but many of the newer projects are opting for hot water, largely because
they can utilize the flue gas. They also have the ability to use hot water storage tanks to improve boiler efficiency.
Automation is also key, with much of the investment in the packing sheds. Handling the large variety of cell packs, bags, trays and resealable plastic packs can be quite time-consuming, so automation is addressing this challenge.
University of Guelph professor Dr. Medhat Moussa is working on robotic systems for greenhouse vegetable crops. Keen interest is also being shown in
lighting. There are about 65 acres in the region using artificial lighting, with more being added each year. “A lot of growers are interested in researching and trying out LED lighting.”
Growers are very efficient with their energy management, and that’s helping keep overall costs down. “For example, they’re venting more carefully,” says Khosla. Growers are optimizing their computer programs to ensure the ideal environment for their crops.
Growers are also becoming more efficient in their use of fertilizer and water. “They’re quite precise in their watering, making sure the amount of water they’re giving the plant is exactly what the plant needs.”
There’s a lot of work being done on new water recycling and disinfection systems.
Educational programs are being developed by the Ontario Greenhouse Vegetable Growers, the Ontario Ministry of the Environment and OMAFRA to help growers comply with new water use regulations.
Under the Nutrient Management Act, for example, growers are now able to apply used greenhouse nutrient solution to farmland. There are a number of regulations that have to be followed.
Other growers have the ability to connect to municipal sewer systems.
The growing season featured a mild winter, but featured low light conditions that led to a slight delay in some of this year’s crops. Growers had to be especially careful how they watered because they could easily overdo it under such low light conditions.
Disease and pest challenges have been about normal for most greenhouse vegetable crops in Ontario over the past year, though whiteflies were a little more challenging than usual.
“Overall, there have been the usual disease and pest pressures,” notes Cara McCreary. “The key for growers is to respond quickly after a problem has been detected.”
While whitefly was a problem, many growers were able to keep it under control using a variety of tools. One example is yellow sticky tape, which is strung the length of a row just above the canopy. “It’s amazing how many adult whitefly it catches,” she says. “Adults
are difficult to control, so this has been effective for many growers.”
More yellow sticky tape was strung this year, probably prompted by last year’s whitefly problem.
Some growers strung the tape atop every row, while others opted for every other row. However growers who used it over alternate rows found much higher whitefly numbers in the rows without the tape, and are doubling up their efforts this year by putting the tape over every row.
“It’s important to put it up early in the season,” says McCreary. The tape lasts for the season and is raised as the canopy grows taller.
Biocontrols are also effective. “We rely quite heavily on them for whitefly control.”
There’s a lot of work being done on new water recycling and disinfection systems.
This past mild winter and fall meant a greater potential for pest problems. There would have been much more pest pressure than normal going into the winter, and potentially higher survival rates for pests over the winter. “Growers were especially alert for problems this year because of the weather. They’re very quick to respond, and that is so important.”
McCreary works closely with Dr. Rose Labbé, AAFC’s greenhouse entomologist at Harrow.
Lighting trials are among current entomology research themes. “How does supplemental lighting affect pests and do they develop more quickly or more slowly under various lighting regimes? Similarly, how does lighting affect biocontrols?”
McCreary says that research over the years has developed very effective biocontrol programs based on regular greenhouse conditions. “What we have to determine is the effect, if any, if you add lighting to the mix,” she explains. “If there is an effect, we may need to adjust the biocontrol programs.”
One key consideration is the diapause
phase some beneficials enter during the winter. Generally speaking, diapause is related to temperature and daylength.
Orius, for example, is a great predator when targeting thrips, but it diapauses through the winter when light levels are much lower. This means there are a number of months it can’t be used. However, could supplemental lighting help break that diapause? The research is underway.
Strawberries are a relatively new commercial crop being grown in Ontario greenhouses. McCreary says there is definitely growing interest in it. “We don’t have a lot of experience with strawberries in greenhouses with respect to pests and other challenges.”
Harrow is conducting extensive research on the crop. Labbé and McCreary are monitoring the trials to assess the pest pressures, and are also working closely with commercial growers.
“It’s a learning curve for everyone. Even with predators and parasitoids, they have preferences with host plants.” For example, would predators that are effective in controlling a pest in a tomato crop be as effective against that same pest in a strawberry crop?
McCreary is also checking on field strawberry biocontrol programs to assess what could also work in a greenhouse.
The major pest threats for greenhouse strawberries are thrips and two-spotted spider mites. Powdery mildew is also a problem, but usually in patches.
She will also assist with efforts to register new products. “There are a limited number of products available right now.”
On a related theme, organic greenhouse vegetable production is also increasing in the province. “Growers currently have a limited range of available products and IPM programs will rely even more heavily on bio-agents.”
Work will also continue on biopesticides and beneficial microbes. Both have great potential for use by organic and conventional growers. They have reduced risk for resistance development and reduced risk for workers.
“It’s important to have access to a combination of conventional and bioagent products,” notes McCreary.
“This is important in reducing resistance.”
Hydroponic Food Production, Seventh Edition is a comprehensive guide to soilless culture with extensively new and updated contents from the previous edition published in 2001. The book:
• shows the reader how to set up a hydroponic operation using the many hydroponic cultures presently used in the industry to grow vegetable crops
• provides background in plant physiology and nutrition essential for growing these crops
• describes nutrient formulations and their applications in nutrient solutions with calculations
This practical guide to soilless growing practices provides detailed information on how to design, set up, and operate hydroponic culture systems. Featuring more than 500 photographs, drawings, and tables, the seventh edition of this bestselling book has been extensively updated and expanded.
The text describes the most successful growing cultures to use with specific crops and details media as well as hydroponic techniques. Chapters cover nutrient uptake and mixing as well as deficiencies and their symptoms, plant nutrition, nutrient solution, water culture, tropical hydroponics and special applications, plant culture, nutrient film technique, gravel culture, and more.
Our roundup of the newest alternative energy initiatives includes projects for northern regions, solar panels, waste heat capture and CO2 systems for biomass boilers.
BY TREENA HEIN
In our August edition last year we presented an overview of a few of the new alternative energy projects across the country. This year, we have more exciting news to share, along with some recent updates.
Let’s start with the updates.
Borealis Geopower has now officially partnered with the Village of Valemount, B.C., and the Valemount Community Forest (VCF) to develop a unique renewable energy eco-park that will include greenhouses. Energy from the site, one of Canada’s best-known geothermal hot spots, will be harnessed for heat and potentially also electricity generation.
The location is a 240-acre brownfield site south of the village, recently purchased by VCF. In
addition to greenhouses, the “Geo-Park” will feature a brewery, an aquaculture facility and projects relating to eco-tourism and forestry.
Next we go to Policella Farms in Kingsville, Ontario, where Rick Policella provides an update on their 200 kW solar energy project, installed three years ago. Policella Farms is a fourth generation, family-owned grower, packer and shipper of premium greenhouse tomatoes, peppers, cucumbers and other specialty products, with another facility in nearby Detroit.
The firm’s solar project includes about 1,050 panels, with 20 invertors that allow them to perform at peak capacity even on days with low light levels. Policella says the system is working well
TOP: The prototype “northern” greenhouse in Espanola – only the south-facing wall is glass. ABOVE: Solar panels being trialled in Alberta.
and there have been no headaches. “We did our research ahead of time,” he notes. “We expect to achieve our return on investment within the next two years.”
Research in Montreal into biomass greenhouse heating is still going strong. The project was started two years ago and is led by Dr. Mark Lefsrud, a professor at McGill University. It is funded by BioFuelNet Canada.
Lefsrud and masters student Yves Roy designed the Biomass Furnace Flue Gas Emission Control System (GECS), which recaptures lost energy and CO2 from a wood pellet furnace and redirects it to the greenhouse. GECS consists of a rigid box air filter coupled with two sets of heating elements and a catalytic converter. Test results show the greenhouse air is well within Health Canada’s air quality guidelines for indoor gas mixtures and contaminants. Lefsrud notes that end-users may even be able to claim a carbon credit.
The McGill team has applied for a patent for GECS and is busy enhancing the product to get it ready for market. Team members are adding a control system to allow growers to adjust CO2 levels. Lefsrud says testing in a full-scale commercial greenhouse will be carried out this fall.
“We replaced the front-end filter HEPA system with a combined electrostatic cyclone system, which can pull out 96 per cent of particulate matter,” he explains. “This particulate removal system can be used on any biomass system.”
California-based Soliculture is expanding a project the company began in 2014 at the Alberta Innovates Technology Futures greenhouses in Vegreville.
The expansion is supported by funding from the province’s Climate Change and Emissions Management Corporation.
Soliculture partnered with another company called Solaria to create their commercial greenhouse solar panels known as LUMO. These panels improve light quality for plants by amplifying beneficial wavelength colours and also generate electricity with no loss to production.
Circling back to geothermal, the first of many planned yearround greenhouses is under construction in Magrath, Alberta (otherwise known as the Garden City). When complete, the flagship “Starfield Centre” (designed and built by Ag Spectra Whole Earth Science and Technology) will house an indoor community park, fruit trees, berries, grapes and veggies.
The project’s first harvest is expected this month. By 2020, Ag Spectra hopes to have 70 other Starfield Centres across southern Alberta.
Ag Spectra CEO Lonnie Mesick says each greenhouse will be about 20 acres, with about 20 geothermal wells for a worstcase scenario of -40 C winter weather. “We are not planning for additional heating,” he explains, “with the exception of stored thermal mass heat.”
The design uses a high-strength, fluorine-based, self-cleaning plastic. “The glazing is manufactured in pillows that are interlocking with a custom-extruded aluminum frame and cable trusses for the support,” Mesick explains. “Proof of concept was worked out in Israel and China before coming to Canada two years ago.”
He gives the total cost per 50-metre by 80-metre greenhouse as less than $600,000 and expects each operation to be profitable within three years.
Construction of a commercial-scale aquaponics greenhouse is expected to begin this summer in Espanola, about 90 kilometres west of Sudbury in northern Ontario.
“We expect to achieve our return on investment within the next two years.”
Melissa Osborn, Soliculture’s director of engineering, says her firm sizes each LUMO system so it will produce enough electricity to offset each grower’s annual usage. “In our experience, there is enough area on the roof of commercial greenhouses to…offset even the most energy-intensive greenhouse operations,” she explains. “Our LUMO panels generate 50 to 100 watts per square metre of greenhouse area.”
There are now panels on the roof of two of the Vegreville greenhouses. “We have been monitoring power output of the system for almost two years,” Osborn explains, “as well as performing plant trials under the panels on several crop varieties.”
SunSelect, based in Aldergrove, B.C., is gearing up to use excess heat and CO2 from Caterpillar’s natural gas cogen facility in Mossville, Illinois, in greenhouses to be built near the plant. The SunSelect greenhouses will operate year-round, and serve as the company’s Midwest hub for both production and distribution. Up to 300 permanent jobs will be created.
Involved in the project are Cambrian College, Helios Whitefish River First Nation and a company called Greenhouses Canada. The 16,500-square-foot facility will produce lettuce, broccoli, tomatoes, cucumbers and tilapia, and include office space and a farmers market.
The design for the greenhouse was developed by Kameal Mina, a professor in the engineering, technology and environmental studies department at Cambrian College (Sudbury), in 2010. Retired professor Josef Hamr also contributed.
In 2013, Jeff Scharf approached Cambrian College with interest in adopting this concept for year-round greenhouses, which led to the creation of his firm, Greenhouses Canada.
A pilot-scale greenhouse using the same design has already been built, housing cucumbers, lettuce, tomatoes, passion fruit, pomegranate and more. It was funded by Ontario Centres of Excellence and the National Research Council and built by Greenhouses Canada staff and Cambrian College students.
In both the pilot and commercial greenhouses, only the south-facing wall is glass. The rest are heavily insulated “double staggered” walls, with an R-value of between 50 and 60 and a construction design where two-by-fours are alternated vertically in a staggered fashion.
The main heat source for the pilot greenhouse is in-floor electric, but Mina says a biomass cogen system is being explored for the commercial venture. The commercial building will also employ passive heating and cooling through thermal masses such as flooring and water reservoirs, with a total yearly heating bill expected to be only $1,500.
Treena Hein is a freelance writer in Ontario.
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If it’s true that each food unit we consume now takes about 10 units of carbon energy to produce, then perhaps the food system is broken. Surely it does not make sense to use more energy to produce something than we can get back out of it in useful food energy. What options do we have?
Firstly, we can reduce the carbon energy input. There’s a whole bunch of “alternative energy” options: oil, propane, coal, wood pellets, wood chips, cord wood, beetle infected wood and dried corn kernels. Unfortunately these are all carbon sources, so we’re not really reducing our carbon input. Other possible fuel sources, while also (ultimately) carbon, make use of otherwise “waste” products (although pine beetle infected furniture is selling for a good price as designer “Denim Pine”). These include used vegetable oil (a great alternative to power diesel engines), methane from landfill (removing this aggressive “greenhouse gas” from the equation), on-farm bio-diesel production, bio-digestion (a number of examples now exist across the country), and even getting heat from the composting process using long lengths of flexible pipe winding its way through the compost pile.
Using waste heat from another industry is a great way to utilize (probably carbongenerated) waste, but of course depends on a
heat for use once the sun goes down. They also (typically) have a brick or stone north-facing wall to absorb the daytime energy, and often also have large amounts of water (in plastic bottles or tanks under the floor of the greenhouse) to also store that captured energy. Such passive houses rely on non-carbon energy (solar), and so can be seen as “green.” But they may not be viable for our familiar large-scale commercial greenhouse businesses of today.
Solar panels on the roof of a passive solar house can also provide both warm water and electricity, so this may be a useful option.
Wind may be another option. While most likely used to generate electricity (which of course may be used to heat underground cables, for example) it’s less likely to be suitable purely for heating greenhouses. And again, selection of a windy enough location is critical.
Perhaps a simple option is to use multiple greenhouse layers, as per Eliot Coleman’s technique at Four Season Farm in Maine. Using low poly-tunnels to cover crops within a larger poly-house, Coleman says each layer of plastic cover equates to “moving” the crop 500 miles south in terms of warmth units. Yeah, OK…but it’s not going to provide sweet cherry tomatoes in quantity in Ontario in February.
We shouldn’t look for a silver bullet, one-size-fits-all solution.
suitable location and a partnership (e.g. the new SunSelect project). “More and more greenhouses that use residual heat and CO2 from a nearby power plant have developed lately, such as the 7.6-hectare Red Tomatoes Productions nursery of Austrian grower Zeiler, located near Vienna International Airport.”1
So, what else is there? Geothermal has been much in the news lately (e.g. see Greenhouse Canada, July 2015). But like waste factory heat, it also depends on choosing a location that specifically works for this energy source.
Perhaps passive solar greenhouses are an option? Of course, traditional glasshouses and poly-houses are “passive” in that they rely on heat from the sun to heat them during the daytime. But we’re talking here about many of the greenhouses in rural China that store that
Perhaps we shouldn’t look for a silver bullet, a onesize-fits-all solution. But maybe we could consider a mix of all options (which is what passive solar greenhouse designers are doing). After all, this superficial review has revealed around 20 options.
Or, perhaps, the future is not to use a glasshouse at all. Perhaps the ubiquitous news items about “vertical” or “container” systems are not a coincidence? Having an insulated shell obviously reduces heat loss, so that’s not a bad thing.
Or, maybe, there is no one solution. Perhaps there is actually room for us all, if we are each conscious of our (carbon) energy use. Which is, after all, where we started this conversation.
1 www.HortiDaily.com, March 16, 2016.
Gary Jones is co-chair of horticulture at Kwantlen Polytechnic University, Langley, B.C. He serves on several industry committees and welcomes comments at Gary.Jones@kpu.ca.
