Tennessee Greentimes - Winter 2023

Vol. 24/NO. 4

Winter 2023

The Official Publication of The Tennessee Nursery and Landscape Association

Cover Crop Options that Provide Benefits for Tennessee Nurseries Plus: Highlights from TNGRO

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Vol. 24/NO. 4 • Winter 2023

The Official Publication of The Tennessee Nursery and Landscape Association

R E CE N T EV ENT Highlights from 2023 TNGRO

8

COVER S TORY Cover Crop Options that Provide Benefits for Tennessee Nurseries

12

M O R E F E A T URES Applying Science-based Solutions Toward Solving Turfgrass Management Challenges................................................................ 24

DEPARTMENTS From the Director..................................................................................................................... 6 From the President................................................................................................................... 6 TNLA Sponsors........................................................................................................................ 6 Welcome, New TNLA Members............................................................................................ 26 Index of Advertisers................................................................................................................ 26

4

tennessee greentimes WINTER 2023

FE A TU R E Achieving Sustainability in the Landscape: The Sustainable SITES Initiative

18

The Tennessee Nursery and Landscape Association serves its members in the industry through education, promotion and representation. The statements and opinions expressed herein are those of the individual authors and do not necessarily represent the views of the association, its staff, or its board of directors, Tennessee GreenTimes, or its editors. Likewise, the appearance of advertisers, or their identification as Tennessee Nursery and Landscape Association members, does not constitute an endorsement of the products or services featured in this, past or subsequent issues of this quarterly publication. Copyright ©2023 by the Tennessee Nursery and Landscape Association.

Tennessee GreenTimes is published quarterly.

Subscriptions are complimentary to members of the Tennessee Nursery and Landscape Association Third-class postage is paid at Jefferson City, MO. Printed in the U.S.A. Reprints and Submissions: Tennessee GreenTimes allows reprinting of material. Permission requests should be directed to the Tennessee Nursery and Landscape Association. We are not responsible for unsolicited freelance manuscripts and photographs. Contact the managing editor for contribution information.

Advertising: For display and classified advertising rates and insertions, please contact Leading Edge Communications, LLC, 206 Bridge Street, Suite 200, Franklin, TN 37064, (615) 790-3718, Fax (615) 794-4524.

North Pole Arb

Franklin’s Gem Boxwood

China Girl Holly

Emerald Green Arb

Sullivan Cypress

Winterthur Viburnum

Excelsa Arb

Member of the Boxwood Blight Cleanliness Program with University of Kentucky.

OFFICE PHONE: 606-346-0863 • FAX: 606-346-2139 • MIKE’S CELL: 606-706-1620 EMAIL: brownsnursery@yahoo.com

Green Giant & Nigra Arbs

Sprinter Boxwood

American Boxwood

Gem Box Inkberry

Nova Taxus

Uptight Boxwood

Green Mtn. Boxwood

Green Gem Boxwood

Steeds Holly

Popcorn Viburnum

Chicagoland Green Boxwood

Hicksi Taxus

Firelight Hydrangeas & Sprinter Boxwoods

Densiformis Taxus

Pragense Viburnum

Polar Gold Arb & Sky Pencil Holly

Wintergem Boxwood

MIKE BROWN’S WHOLESALE NURSERY, LLC. • 525 HOLTZCLAW LANE • HUSTONVILLE, KY 40437

TNLA would like to thank the following companies for being

MEMBERSHIP SPONSORS GOLD Membership Sponsors Barky Beaver Mulch & Soil Mix, Inc. BASF Blankenship Farms and Nursery Bobcat of McMinnville Botanico, Inc. BWI of Memphis Cam Too Camellia Nursery, Inc. Cherry Springs Nursery Delta Mulch and Materials, LLC Flower City Nurseries Gravely NYP Corp.

Putnals Premium Pine Straw, Inc. Randall Walker Farms Riverbend Nurseries, LLC Super-Sod Swafford Nursery, Inc. Swift Straw Tennessee 811 Tennessee Valley Nursery, Inc. Warren County Nursery, Inc. Youngblood Farms, LLC

SILVER Membership Sponsors 3F - Flanders Family Farm Dayton Bag & Burlap Co. Mid-South Nursery Mike Brown’s Wholesale Nursery, LLC Old Courthouse Nursery Rusty Mangrum Nursery Samara Farms Turf Mountain Sod

From the Executive Director

Thanks for the Opportunities and Blessings of Serving the Past 30 Years!

In

a few short months, I will be retiring from TNLA. Looking back at where I began, and now thirty years later, where I will finish seems like a short time. I never imagined when I started that I would retire from this job. I have enjoyed my time at TNLA and have had some amazing mentors, friends, office staff, and board members. When I started, I never imagined working in an industry with so many compassionate people.

So many have asked what I plan to do with my time, and I can tell you that I will be busy at home. Hopefully, God will bless me with several more years and I can enjoy doing more for others. Life is short… enjoy every minute and be thankful for all your experiences both good and bad.

Thanks for the memories,

Louree Walker TNLA Executive Director

From the President

“You may delay, but time will not” – Benjamin Franklin

Dear Members, I have enjoyed my time as President of TNLA this year and appreciate the wonderful members and staff that I have worked with. My time on the board seems to have gone by fast and yet I know each day is the same. When I think about the progress of this association, I know that we did our best to not delay. We have seen great success in tough times with health and economic crisis. We appreciate all that our members have done to help keep us successful during these times. As we look forward to what challenges lie ahead, I know that our members will not delay preparing for the future.

We had a strong tradeshow and appreciated our Sponsors and Exhibitors. Events like this are what keeps TNLA strong and growing. We are so blessed to work in an industry like ours where we can rely on each other during the good and bad times. Our allied partners are always here for support, products, and services that as members we all need. I would also like to recognize our Association’s long-standing Executive Director Louree Walker and thank her for her years of service. We are also happy to welcome our new executive director, Danae Bouldin. I would like to thank the members of this great association for the opportunity to serve and wish the new board much success.

Terri Turner TNLA President 6

tennessee greentimes WINTER 2023

Louree Walker

Terri Turner

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Charlotte Simmons was awarded the Floyd MacDonald Scholarship in recognition of her outstanding academics in horticulture studies at Tennessee Technological University.

Recent Event

Once again, TNLA members and friends enjoyed a fantastic celebration of another year of work well done! The TNGRO event, held September 28 – 29 at the Farm Bureau Expo Center in Lebanon, highlighted our trade show vendors and booths as well as award winners and Hall of Fame inductees.

Take a look at some highlights from this memorable gathering.

8

Best of Show Green Goods

Best of Show Hard Goods

Dewar Nurseries, Inc.

H&R Agri-Power Farm & Turf

1st Place

1st Place

Best of Show Green Goods

Best of Show Hard Goods

Place Pack’s Nursery

Barky Beaver Mulch & Soil

2nd Place

2nd Place

Best of Show Green Goods

Best of Show Hard Goods

Warren County Nursery, Inc.

Mize Farm & Garden Supply

3rd Place

3rd Place

tennessee greentimes WINTER 2023

Tennessee Nurseryman of the Year

Salesman of the Year

Young Nursery Professional of the Year

Tommy Boyd

Chris Hackler

Wilson Love

Boyd & Boyd Nursery

Drees Plant Wholesalers

Love Farms & Nursery

Landscape Contractor of the Year

Ooltewah Nursery & Landscape Co., Inc.

TNLA made a $500 donation to Williamson Fire and Rescue on behalf of Steve Bennett at Riverbend Nurseries, Inc.

Hall of Fame

Posthumously, Tony Cope

Green Goods Distributor of the Year

Signal Mountain Nursery

Hall of Fame

Dr. Douglas Airhart Tennessee Technological University (accepted by Dr. Kenny Pierce on his behalf)

Danny Pirtle Pirtle Nursery, Inc.

Hall of Fame Witty Creek Nursery (accepted by his son Matt, daughter Meredith, and wife Carolyn)

tennessee greentimes WINTER 2023

9

Thank You – TNGRO 2023 Sponsors

GOLD BASF

Farm Credit Mid-America

Harrell’s

Trivett’s Nursery, LLC

BWI of Memphis

Flower City Nurseries

JLPN, Inc.

Turner & Son’s Nursery

SILVER Botanico, Inc.

Faron Green Nursery

Nashville Landscape Systems

Samara Farms

Cam Too Camellia

John Holmlund Nursery, Inc.

Scenic Hills Nursery

Douglas & Lanier Agency, Inc.

Mid-South Nursery

Ozzy’s Lawncare & Hardscape Services

Drees Plant Wholesalers

Morton’s Horticultural Products

Randall Walker Farms

Turf Mountain Sod, Inc.

BRONZE Albertville Wood Products Barky Beaver Mulch & Soil

Cherry Springs Nursery Corteva Envu

J.B. Donoho Nursery Mize Farm & Garden Supply Rusty Mangrum Nursery

Simpson Nurseries of TN Southern Ag

Happy Holidays!

From Your Friends at

FairviewEvergreen.com 7463 West Ridge Rd. P.O. Box 189 Fairview PA 16415 800.458.2234

10

tennessee greentimes WINTER 2023

Thank You – TNGRO Exhibitors 2 Guevara Nursery

J & D Nursery

Pleasant Cove Nursery, Inc.

Swift Straw

ACI Distributors, Inc.

Keevan’s Green Thumb Nursery, Inc.

Randall Walker Farms

Tennessee Dept. of Ag. – Pick TN

Agricultural Workforce Management Association, Inc.

Kinsey Gardens, Inc.

RediRoot

Little River Nursery, Co.

Richey Nursery Company, LLC

Tennessee Dept. of Ag. – Plant Certification

Albertville Wood Products

Living Earth

River Rock Nursery

Anderson Mulch & Soil, LLC

Magness Nursery

Riverbend Nurseries, LLC

Barky Beaver Mulch & Soil, Inc.

Merritt Nursery, Inc.

Rubley’s Nursery

BDI Machinery Sales, Inc.

Middle Tennessee Nursery Association

Rusty Mangrum Nursery

Mid-South Nursery

Scenic Hills Nursery

Best Management Practices BioPlex Organics BioSafe Systems Blackmore Co., Inc.

Safeguard

Tennessee Nursery & Landscape Association, Inc. Tennessee State University Research Center Tennessee Valley Nursery, Inc. Tree Farm Nursery & Liners

Mize Farm & Garden

Schaeffer Manufacturing

Morton’s Horticultural Products, Inc.

Simpson Nurseries

Mulch Manufacturing Inc.

Specialty Tag & Label, Inc.

Blankenship Farms & Nursery

National Nursery Products, Inc.

Botanico, Inc.

Spring Creek Nursery

Newby Tree Farms

Spring Meadow Nursery Steve Myers & Son Nursery

Triangle Nursery, Inc. TriGreen Equipment Trivett’s Nursery Tupper Tree Farm Turner & Sons Nursery Underwood True Value Hardware & Nursery Supply

Boyd & Boyd Nursery

NYP Corp.

Buffalo Horticulture Sales Company

OHP, Inc.

Stilt Pro Equipment

BWI Companies, Inc.

Old Courthouse Nursery

Sunset Transportation

UT Extension – Dept. of Plant Sciences

Cam Too Camellia Nursery, Inc.

Pack’s Mfg.

Superb Horticulture

Walker Nursery Company

Cedarwood Nursery

Pack’s Nursery, Inc.

Superior Trees, Inc.

Warren County Nursery

Center Hill Nursery, LLC

Panter & Sunderland

Surface Nursery, Inc.

Wilcher’s Nursery

Pirtle Nursery, Inc.

Swan Mill Nursery

Woodbury Insurance Agency

Centertown Nursery Cherokee Manufacturing

Plant & Supply Locator

Cinch Packaging Classic Groundcovers, Inc. Clifford’s Perennial & Vine Crossroads Sod Farm, LLC Day Spring Nursery Dayton Bag & Burlap Decker’s Nursery Del Norte Harvesting, LLC Dewar Nurseries, Inc. Dry Shave Mountain Nursery Dutchman Tree Spade Evins Mill Nursery Farm Credit Mid-America Fieldworks Nursery Equipment FiNN All Seasons Flower City Nurseries Forest Nursery Co., Inc. Garretson Stone, LLC Gravely Griffin Grower Direct Supply H & H Farm Machine Co., Inc. H & R AgriPower Hale & Hines Nursery Co. Hans Nelson & Sons Nursery, Inc. Harrell’s Haston Farm Nursery Haviland Plastic Products Heather Farms Nursery, Inc. Herd Farms Nursery Hildreth Brothers Nursery Home Nursery, Inc. Irrigation-Mart

tennessee greentimes WINTER 2023

11

Cover Story

Cover Crop Options that Provide Benefits for Tennessee Nurseries

By Dr. Anthony Witcher 1 and Grayson DeLay 2 1Associate Professor and 2Graduate Masters Student, Tennessee State University, Otis L. Floyd Nursery Research Center

T

ennessee has over 19,000 acres in production of nursery crops with more than half of that total area planted with field-grown trees and shrubs that will be harvested as barerooted liners or dug as balled and burlapped (B&B) stock. Fertile and well-drained soils are critical for producing quality nursery stock.

Yet in these systems, continuous cycles of nursery production with successive crop harvests leads to removal of topsoil and reduced soil quality. In many scenarios, once a new crop has been transplanted to the field, the soil surface can remain bare for several months until grasses and broadleaf weeds are able to establish in the nonproduction middle areas between rows. In this period, bare soil is susceptible to structural breakdown and soil erosion that are made worse during heavy rain events and windy conditions (Figure 1). Soil degradation and erosion also occurs in nursery middles subjected to

frequent tillage. The action of tilling will produce a shallow hardpan that limits water infiltration into the soil, making it more difficult for water to reach the crop root zone. Heavy equipment travelling through nursery middles for tillage and mowing also can degrade soil structure by compacting the soil leading to increased rainwater runoff and reduced water infiltration. Harvesting B&B crops removes large amounts of fertile topsoil from production areas, and it is cost- and labor-prohibitive to replace by importing new soil or organic material to the fields. Instead, producers can take advantage of implementing best management practices to their operation that will reduce soil degradation and improve soil properties, thereby maximizing the success of future crops. Cover crops are a versatile tool that can be used to reduce erosion and improve soil quality and cover crop options also can help restrict or suppress various crop pests.

FIGURE 1. Soil erosion resulting from heavy rainfall in a nursery field.

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Cover Story continued

Types of Cover Crops Cover crops are plant species that are grown during the fallow crop period or that can be intercropped between the primary crop rows to “cover” the soil while also providing numerous benefits.

Cover crops can enhance soil properties by reducing soil erosion, facilitate increased rain infiltration into the soil, add organic matter and nutrients, and break up compacted soil. Cover crops can also complement existing pest management strategies by outcompeting weeds, providing habitat for beneficial insects, and reducing soil pathogen populations. There are two main groups of cover crops: grasses [sudex (Sorghum bicolor x S. bicolor var. Sudanese), winter wheat (Triticum aestivum), etc.] and broadleaf plants (clovers, mustards, etc.). Broadleaf cover crops are also subdivided into legume and non-legume crops. Legumes are able to supply additional nitrogen through the symbiotic relationship that these crops have with nitrogen-fixing bacteria (Rhizobium spp.). Cover crops may also be referred to as cool season [crimson clover (Trifolium incarnatum), winter wheat, etc.] or warm season [cowpea (Vigna unguiculata), sudex, etc.] crops, which provides an indication of the time of year that the cover crop will be actively establishing and growing. In Tennessee, cool season cover crops will typically be planted in late August through October. Warm season cover crops are planted in mid- to late spring. Although cover crops can provide numerous benefits, care should be taken to avoid selecting species that may reseed and become weedy [i.e., annual ryegrass (Lolium multiflorum)] or that grow with a vining/spreading habit [i.e., hairy vetch (Vicia villosa)] that can quickly overtake small crops. Cover crops can be utilized throughout the nursery crop cycle, yet cover crop species should be selected based on the intended primary goal or benefit they provide, such as erosion control, correcting compacted soil, or increasing organic matter.

Cool Season Cover Crops Cool season cover crops are a great option for use in Tennessee nurseries during the crop cycle. Cool season cover crop species will establish during the fall/winter, mature in late spring, do not interfere with nursery tasks, and can improve field access for harvesting crops during the winter months (Figure 2). Planting a mix of two or more cover crop species is recommended to maximize establishment and gain advantages of each individual cover crop species. The USDA National Resource Conservation Service local county offices are an excellent resource for providing details on selecting cover crop species for mixes and for recommended planting rates. Once the desired cover crop mix has been selected, growers can contact a cover crop seed vendor which can mix the cover crop seeds based on the recommended planting rates.

Crimson clover has been widely used in Tennessee nurseries due to its ease of establishment, low growth habit, and nitrogen fixation capability. Crimson clover is an annual plant that can reseed naturally but should be replanted each year to achieve optimum benefits. To achieve maximum nitrogen fixation, all legume cover crop seed must be pre-inoculated or inoculant can be purchased separately and added to the seed mix. Cereal grasses such as cereal rye (Secale cereale), winter wheat, and triticale (×Triticosecale; a hybrid of rye and wheat) are choices that grow well in Tennessee, survive throughout the winter, and naturally senesce in May.

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FIGURE 2. Cool season cover crop mix (triticale and crimson clover) in April at a commercial nursery in Tennessee.

FIGURE 3. A cool season mix including tillage radish that was planted in February at a Tennessee nursery.

Cover Crop Mix

MIX #1

Cover Crop Species

Seed Planting Rate (lb/acre)

Cereal Grass (cereal rye, winter wheat, or triticale)

75

Crimson Clover

15

Comments General use mix for nitrogen fixation, soil stabilization, weed suppression

Total = 90

MIX #2

Cereal Grass (cereal rye, winter wheat, or triticale)

40

Crimson Clover

9

Tillage Radish

5

Buckwheat

15

General use mix for nitrogen fixation, soil stabilization, and to reduce soil compaction

Total = 69

MIX #3

Cereal Grass (cereal rye, winter wheat, or triticale)

40

Crimson Clover

9

Tillage Radish

4

White Clover

3

Red Clover

3

Mix for maximum benefits such as nitrogen fixation, soil stabilization, weed suppression, early summer cover, and to reduce compaction

Total = 59

TABLE 1. Cool season cover crop mixes for Tennessee nurseries.

FIGURE 4. All-purpose overseeder used for planting cover crops in between nursery production rows.

These grasses stabilize the soil by producing deep roots, generating biomass for increased organic matter, scavenging for nutrients deep in the soil, and suppressing weeds. Additional legume cover crops for use in cool season mixes include Austrian winter peas (Pisum sativum subsp. arvense), white clover (Trifolium repens), and red clover (Trifolium pratense). Winter peas provide extra nitrogen, but plants will winter kill at temperatures below 15ºF so survival will vary due to winter conditions. Red clover is a short-lived perennial that can persist into the summer but will go dormant in extreme heat. For this reason, red clover needs to be reseeded every couple of years. White clover is a long-lived perennial that makes a great living mulch in nursery middles when wellestablished. Dutch white clover is a shorter variety and tolerates frequent traffic. Its ability to naturally reseed helps Dutch white clover to persist across time. Ladino white clover is taller with larger leaves, and creates more biomass than Dutch white clover.

However, Ladino white clover is not as heat tolerant and will need to be reseeded each year. To gain additional benefits from a cool season mix, consider adding a few other non-legume crops. Tillage radish (Raphanus sativus), a member of the mustard family, grows with a large taproot that will break up compacted soil and increase rain infiltration (Figure 3). Buckwheat (Fagopyrum esculentum) is a short-lived plant that germinates quickly, produces numerous flowers that attract pollinators, and is sensitive to frost making it a great crop for cool season mixes.

Cover crop research at Tennessee State University through the Otis L. Floyd Nursery Research Center has identified compatible cover crop mixes, ideal planting methods, and optimum planting rates for Tennessee nurseries. Crimson clover + triticale is a great all-purpose cool season cover crop mix that consistently performs well under nursery conditions. Several other mixes can be used depending on the desired goals (Table 1). Cover crops can be planted using a broadcast seeder, which is the most cost-effective method, yet large-seeded species like the cereal grasses and tillage radish will not germinate well due to insufficient soil contact.

Additionally, seed that is broadcast will also germinate and grow within the nursery production rows leading to competition for water and nutrients between the cover crop and the nursery crop which results in reduced nursery crop growth. In other cropping systems, seed drills are widely used for planting cover crops, however seed drills can be very expensive with most models engineered to be too wide for use in normal nursery middle spacing.

All-purpose overseeders (Figure 4) are cost effective options for planting seed in nurseries. These overseeders work by opening the soil surface with disc blades or a spike drum, then seed is dropped onto the soil surface, and a cultipacker presses the seed into the loose soil. All-purpose overseeders have narrow, 4 to 5 ft-wide planting widths, which are ideal for nursery middles and are available from several manufacturers. To maximize cover crop germination and establishment, a few guidelines should be followed.

Prior to planting with an all-purpose overseeder, nursery middles should be mowed close to the soil surface. Collect clippings or prepare ground to have minimal plant residual debris remaining.

This is important because germination success requires adequate direct contact with the soil. Additionally, schedule the seeding activity prior to a rainfall event because that will maximize seed germination. Avoid planting into severely dry soil because the overseeder will be less effective at breaking up the soil surface.

tennessee greentimes WINTER 2023

15

Cover Story continued

Using Cover Crops in Nurseries Cover crops can be grown on fallow ground, into which no nursery crops have been planted, as a preliminary step intended to increase soil organic matter prior to transplanting a future nursery crop. To start, plow and fill in root ball holes from the previous crop. A cover crop of sudex, which is a hybrid of sudangrass and sorghum that increases organic matter and suppresses weeds, can be sown May to June at 50 lb/acre. Sudex can grow up to 8 ft tall but should be mowed once it reaches 3 to 4 ft tall to maximize root and shoot biomass (Figure 5). In September, sudex should be turned under using a chisel plow. At this time, a cool season cover crop mix should be planted to stabilize the soil and suppress weeds during the winter. After taking these steps, the field is ready for transplanting a nursery crop the following spring. After planting the nursery crop, a cool season cover crop mix can next be planted into the row middles in late summer/early fall each year to help replenish soil organic matter during the crop production cycle. Alternatively, a cool season cover crop mix can be planted in late winter (February to early March) to help stabilize soil and suppress weeds in spring. With this latter choice, growers will generally receive less biomass production from cover crops started in late winter. There are several ways to manage the cover crop residue produced by fall and spring-planted cover crops. The cover crop can be left to senesce naturally, allowing the standing stubble to slowly decompose and helping to suppress spring-germinating weeds. A roller-crimper can be used to physically push the cover crop to the ground forming a residual mulch which provides short-term weed control and increases rainwater infiltration, yet this must be done prior to plant maturation (during cover crop flowering but before seed set). The cover crop can also be mowed to chop the residue which will facilitate decomposition into the soil.

Planting cover crops does require additional expenses for seed, equipment, and labor. However, several cost-share programs are available through the Tennessee Department of Agriculture Agricultural Enhancement Program (TAEP) and the USDA National Resource Conservation Service (NRCS) that can help offset the cost of seeders and cover crop seed. Equipment (all-purpose overseeder and roller crimper) can also be rented through the Warren County Soil and Water Conservation District (931-668-4383).

Recent research (see Additional Reading section), including work at Tennessee State University, has identified several benefits to using cool season cover crops in nurseries. Other benefits have included deterrence against flatheaded borer (Chrysobothris spp.) beetle attacks on young trees, suppression of soil-borne pathogens, and suppression of weed establishment. Our team’s ongoing research continues to develop best management practices for using cover crops in nursery production systems.

For more information

on cover crops or weed control practices in nursery crop production, contact Dr. Anthony Witcher ( 931-815-5147, awitcher@tnstate.edu. )

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tennessee greentimes WINTER 2023

FIGURE 5. Sudex cover crop growing in a fallow nursery field.

Additional Resources Managing Cover Crops Profitably. Sustainable Agriculture Research and Education (SARE). https://www.sare.org/resources/managing-covercrops-profitably-3rd-edition Southern Cover Crops Council. https://southerncovercrops.org Cover Crops. Appropriate Technology Transfer for Rural Areas Sustainable Agriculture Program. https://attra.ncat.org/topics/cover-crops Flatheaded Borer Management in Nurseries with Winter Cover Crops. https://www.tnstate.edu/extension/documents/ Flatheaded%20Borer%20Management%20 with%20Cover%20Crops%201.pdf Cover Crop Usage for the Sustainable Management of Soilborne Diseases in Woody Ornamental Nursery Production System.

Canadian Journal of Plant Pathology 44:432-452.

DOI: 10.1080/07060661.2021.2020336.

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2814 Todd’s Point Road | Simpsonville, KY 40067

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Feature

Achieving Sustainability in the Landscape The Sustainable SITES Initiative

By Michael Ross, SITES AP, ASLA, Assistant Professor, Plant Sciences Department + School of Landscape Architecture, University of Tennessee and James D. Zimmerman, MLA Graduate Student, School of Landscape Architecture, University of Tennessee

I

am often asked about references that are available to help designers, gardeners, contractors, and maintenance folks establish more sustainable practices and solutions to common landscape challenges. There are many great resources that provide some basic strategies for residential landscapes and gardens. Suggestions can assist with retrofit and initiation options as well as sustainable enhancements for designs. Often, though, planners find that as the scale of a project increases, or they are facing construction of a completely new development, the ability to maximize sustainability and resilience in the earliest stages can impose some significant challenges…along with real opportunities.

There are several programs that serve as guidelines for pursuing sustainable design, construction, maintenance, and management objectives. In this article, I will focus on The Sustainable SITES Initiative (now, SITES v2).

The Sustainable SITES initiative was developed in collaboration with the American Society of Landscape Architects, The Lady Bird Johnson Wildflower Center, and the United States Botanic Garden. The developers of the SITES concept sought to promote ecosystem services and regenerative landscapes as an investment in resilient futures and ecosystem services. Ecosystem services encompass the goods and benefits that healthy ecosystems provide to people, both directly and indirectly.

The goal of SITES focused on developing a sustainability rating system that would serve a similar role for the landscape that the Leadership in Energy and Environmental Design (LEED) system provided for buildings. Like LEED, SITES provides a rating system that allows projects to earn points and gain recognition for efforts undertaken to integrate sustainability. Initial efforts were undertaken with pilot projects from various parts of the country and at varied scales.

PHOTO 1. University of Pennsylvania athletic precinct at Shoemaker Green public commons (Photo courtesy of Andropogon Associates).

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tennessee greentimes WINTER 2023

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Feature continued

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As feedback came in from participating professionals, credits were added, refined, and clarified. The Sustainable SITES Initiative is now on its second version and is referred to as SITESv2. The enhanced objectives of SITESv2 are to create regenerative systems and foster resiliency, to ensure future resource supply and mitigate climate change, to transform the market through design, development, and maintenance practices, and to enhance human well-being and strengthen community (SITES v2 Reference Guide, 2014). These lofty goals reflect a contemporary understanding and appreciation for the simple fact that landscape is inherently boundless. Although we as designers and planners may be limited to a project site boundary, the decisions, actions, and interventions we take will have impacts beyond the project site.

SITESv2 recognizes four categorical levels that are achieved through meeting prerequisites and achieving point credit accumulations: Certified (70 pts.), Silver (85 pts.), Gold (100 pts.), and Platinum (135 pts.) projects. SITESv2 currently has a total of 200 credits (points) that can be earned. Although a project does not need to earn all possible credits, it must satisfy all the required prerequisites. SITES and SITESv2 are now owned and managed by Green Business Certification Inc. (GBCI), the same company that owns and manages LEED certification. There are now synergies between the two rating systems that allow for credits earned in one to be applied to the other.

At the time of writing, there are more than 290 projects that have been categorized within the Sustainable SITES Initiative. These projects run the gambit from efforts initiated at university campuses (Photo 1), city parks (Photo 2), public gardens (Photo 3), medical facilities, and stormwater mitigation by municipalities. Residential projects also are eligible and could provide some interesting opportunities for expansion of the program. For reference, Tennessee currently has one SITESv2 project, The Woodland Discovery Playground at Shelby Farms, which is located in Shelby County in West Tennessee (Photos 4 & 5).

PHOTO 2.

Xuhui Runway Park in Shanghai, China designed by Sasaki (Photo reprinted with permission, courtesy of Sasaki).

PHOTO 3.

Phipps Conservancy and Botanical Garden in Pittsburgh, PA that was designed by Andropogon Associates (Photo courtesy of Andropogon Associates).

PHOTO 4.

A playground at The Woodland Discovery Garden at Shelby Farms designed by James Corner Field Operations and located in Memphis, TN (image reprinted with permission: photo © James Corner Field Operations)

PHOTO 5.

A splashpad at The Woodland Discovery Garden at Shelby Farms designed by James Corner Field Operations (image reprinted with permission: photo © Shelby Farms Park Conservancy / Rebecca Dailey)

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A SITESv2 Program Overview The process to SITESv2 Certification is organized into four steps. First, the site must be registered by completing key forms and paying the registration fee to receive access to SITESv2 worksheets.

Then, completion and submission of the necessary worksheets and documentation enable GBCI to begin reviewing the project. Thirdly, GBCI will conduct an examination of the project to ensure credibility. Finally, if everything is approved, GBCI completes the final review and awards certification.

Currently the SITESv2 program is broken down into 10 sections with required prerequisites and optional credits. These sections include elements like using an integrative design process and conducting a pre-design site assessment as prerequisites, while reducing outdoor energy consumption and diverting construction and demolition materials from disposal as non-required credits.

It is important to note that not all projects will have the ability to hit all the credits, but projects must achieve all the prerequisites.

Additionally, SITESv2 uses a decision-making hierarchy that focuses on conservation, management, restoration, and generation depending on the initial site conditions. As examples, if your project location had an old growth forest, a designer might prioritize conservation as a key strategy. If, however, the location was formerly a parking lot, the designer would utilize a strategy of reintroducing ecosystem services and regenerative systems. These considerations fall within a series of goals for the SITESv2 project.

A Brief Introduction to A Few of SITESv2 Section Opportunities There are 10 sections of the SITESv2, each with their own prerequisites and available credits. For example, Section 1 deals with site context and focuses prerequisites on minimizing impact to

Feature continued farmland, floodplains, aquatic ecosystems and endangered or threatened species.

Credits can be earned for redeveloping degraded sites, or infill projects.

Section 2 involves the pre-design assessments and requires the use of an integrated design process. This is perhaps one of the strongest arguments for the SITESv2 program. The integrated design process requires that all participants, owner, designers, contractors, and maintenance folks be present and actively engaged in the initial discussions and design planning. Many of us have experienced situations where our voice is left out of the design and planning process only to be brought in after the fact and in some cases too late to effectively guide a sustainable or resilient move on a project. This integration between participants means that everyone is acknowledged as being crucial to the successful outcome of a sustainable project.

Section 3 deals with site design as it relates to water. This includes reducing water use for irrigation, managing stormwater on site, restoring aquatic ecosystems, etc. As with all the sections there are credits that can be earned by using sustainable design best practices.

The remaining seven sections relate to Soil and Vegetation, Material Selection, Human Health and Well-Being, Construction, Operations and Maintenance, Education and Performance Monitoring, and Innovation Exemplary Performance.

Challenges There are several challenges that arise when working towards SITES Certification. One of the main challenges is the cost of the SITES Certification with registration and certification fees can approach $10,000. Keeping track of forms, deadlines, and credits also is time consuming and can take away time from the project itself. This extra time reduces the effort and money that can be put into designing the site. Another challenge is trying to assemble the integrated design team. This requires a variety of stakeholders to agree to joining the team and can take time and communication to form an effective team.

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RESOURCES

Andropogon Associates. (n.d.-a). Phipps Conservatory and Botanical Gardens. Andropogon. https://www.andropogon.com/ project/phipps-conservatory-andbotanical-gardens Andropogon Associates. (n.d.).

Shoemaker Green. Andropogon. https://www.andropogon.com/ project/shoemaker-green/

James Corner Field Operations. (n.d.). Shelby Farms Park. Field Operations – project_details. https://www.fieldoperations.net/ project-details/project/shelbyfarms-park.html Sasaki. (2023). Xuhui Runway Park. Sasaki. https://www.sasaki. com/projects/xuhui-runway-park The Sustainable SITES Initiative. (2014). Sites V2 reference guide: For sustainable land design and development.

Sustainable Sites Initiative.

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Feature

Applying Science-based Solutions Toward Solving Turfgrass Management Challenges Growing playable grasses in shaded and reduced light stadium environments

By Rhys Fielder, MS student, Tyler Carr, Ph.D., John Sorochan, Ph.D., and Kyley Dickson, Ph.D.; Plant Sciences’ Turfgrass Science Program at the University of Tennessee – Knoxville

M

odern-day stadiums are often planned and designed to provide versatile functionality and enhance fan experience.

These stadiums are usually promoted as the home of a particular sports team; however, these venues may also become host sites for events year-round that range from concerts to monster truck rallies.

Currently, ten of the thirty National Football League (NFL) and eight of the thirty Major League Baseball stadiums are either fully enclosed or have large overhangs covering the seating bowl. The encapsulation of the stadium allows for an increase of fan comfort during events, as well as a reduction or removal of environmental factors when planning or hosting events. While these amenities are important for professional venues, any stadium or pitch that receives heavy shade from high walls, overhangs, or partially enclosed roofs, present difficulties to those managing one of the most important assets a stadium has: the playing surface.

We learn and teach these and other practical challenges in undergraduate and graduate level Turfgrass Sciences coursework in the Plant Sciences degree programs at the University of Tennessee. For some undergraduate student interns, as well as MS and PhD students working on cutting-edge research projects to address a knowledge gap, the solution requires understanding the science of interactions between turfgrasses and structures, the players on the field, and the turfgrass managers who are tasked to maintain the highest quality playing surface across the entire span of seasonal use. This understanding is most often informed by our studies of plant physiology, growth, and performance characteristics of different turfgrass species.

In the real-world scenario that we present here, shaded turfgrasses in stadiums experience considerable challenges to photosynthetic processes that would not typically inhibit plant development in an openair environment. Unlike humans, plants have the remarkable ability to generate their own food through the process of photosynthesis. A combination of water, carbon dioxide, and light energy allows the plant to manufacture carbohydrates to be used for energy. These three ingredients can be naturally provided by the environment. Within a stadium environment, irrigation can be used to fulfill water needs and air circulation systems such as fans can even be supplemented to increase carbon dioxide availability. However, one of the most difficult challenges a stadium or partially enclosed structure creates is the imposition of shade that reduces the amount of available light.

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FIGURE 1. Light-emitting diode (LED; top) and high-pressure sodium (HPS; bottom) supplemental lighting systems for use on turfgrass.

(Source: sglsystem.com)

Shade can be defined as a reduction in both light quality and light quantity. Light quality is explained by observing the wavelengths in light, which are measured in nanometers (nm) and range from very short to very long. Turfgrass requires light quality to be within the range of 380–700 nm in order for photosynthesis to occur. Light quantity is the actual particles of light that provide the necessary energy for photosynthesis to occur.

A shade situation appears when there is not enough light energy (quantity) being supplied to the turfgrass for sufficient photosynthesis to occur.

What has been (and can be) done to address these challenges?

In many instances, the simple answer has been to install artificial turf surfaces that do not require light at all. Yet simple solutions can bring challenges and consequences of their own. The decision to switch to artificial turf is often made contrary to player preference and injury data. Results from the NFL Players Association’s (NFLPA) 2010 NFL

Players Playing Surfaces Opinion Study documented that 69.4% of players preferred to play on natural grass versus preference for artificial turf (14.3%). More recently the NFLPA president, JC Tretter, released a statement that calls for all NFL stadiums to have natural grass playing surfaces. Tretter cited NFL injury data collected from 2012 to 2018, which reported that artificial surfaces increased the likelihood of a player suffering a non-contact lower extremity injury by 28% compared to grass. Faced with calls for action and preferences of players, stadiums that have extreme shade issues and boast artificial surfaces are forced to consider the difficult questions: Is it possible for our venue to support natural grass? and How can that turfgrass be managed for playability across event activity and growing seasons?

Answers to parts of those questions can be supported with solutions from supplemental lighting. Supplemental lighting for stadiums is like the lights used in a greenhouse. They work by replacing the photosynthetically active light that a plant would usually obtain from natural sunlight. Supplemental lighting products for stadiums generally rely on illumination from one of two different light sources: high pressure sodium (HPS) or light-emitting diode (LED) (Figure 1). Currently, the most widely used supplemental lighting systems in the United States and worldwide utilize HPS rigs.

Stadiums housing NFL teams in Miami, Jacksonville, Green Bay, and Kansas City have had success using HPS light systems to promote photosynthesis on areas experiencing shade issues. Colder climates, such as in Green Bay, receive added benefits from HPS lights, as these systems can increase temperatures at the grass surface up to 5°F (3°C). Green Bay routinely reports daily low temperatures below freezing between November and January, so the heat emitted from the HPS lights likely allows the grass to recover between games when there would otherwise be little to no recuperative growth, potentially resulting in a safer surface for the athletes. If excess heat from supplemental lighting is not desired, such as a stadium in a hot climate, one may elect to use LED lights.

LED light systems provide two distinct benefits compared with HPS. First, LED lighting uses less energy during operation than HPS systems. The principle is similar to replacing incandescent bulbs with energy-efficient LED bulbs in residential and commercial buildings.

Another benefit of LED systems is the ability of operators to select a desired range of wavelengths from different portions of the light spectrum. This capability is not available with HPS lighting. Although LED systems are currently more expensive up-front than HPS, the gap in cost has been narrowing with advances in technology.

Taking Science to the Gridiron and the Pitch

So how could it be possible for an indoor or heavily-shaded stadium to grow natural grass? Our preliminary results with Kentucky bluegrass show that this species can be grown using supplemental lighting when no natural sunlight is available, like in an indoor stadium. The ability of a turfgrass manager to effectively grow natural grass in a stadium while continuing to host external events will only increase the capability of the venue to generate revenue throughout the year. Current and future research at the University of Tennessee is underway and being planned that will provide innovative solutions to other problems associated with growing turfgrass in situations that require solutions for shade and supplemental lighting.

FIGURE 2. The shade structure at the University of Tennessee where supplemental lighting studies occur.

FIGURE 3. Green turfgrass coverage for Kentucky bluegrass grown exclusively under high-pressure sodium (HPS) or light-emitting diode (LED) supplemental lighting systems from November 8 to December 11, 2019 in Knoxville, TN. Images demonstrate the response of Kentucky bluegrass to HPS (top row) or LED (bottom row) after 0, 14, and 24 days.

Since summer 2019, The University of Tennessee has been conducting supplemental light studies in cooperation with Stadium Grow Lighting to quantify how warm- and cool-season turfgrass species respond when grown under light supplied from only LED or HPS systems (Figure 2).

These are important questions to answer, as indoor stadiums create situations where all light must be supplied supplementally.

An important way to measure how a cool-season grass, such as Kentucky bluegrass, responds to supplemental lighting is to quantify the turfgrass quality. A subjective way to assess quality is by estimating the percentage of green turfgrass coverage over a given area. In general, greater turfgrass coverage corresponds to greater aesthetic quality.

Throughout the trial, our team identified no significant differences in green turfgrass coverage when comparing HPS and LED in the absence of natural light (Figure 3). Kentucky bluegrass maintained turfgrass coverage greater than 90% when grown under both HPS and LED lights. In addition, turfgrass coverage greater than 95% was observed continuously for the first 24 days.

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The Tennessee Greentimes is the official publication of The Tennessee Nursery & Landscape Association, Inc. 115 Lyon Street McMinnville, Tennessee 37110 (931) 473-3951 Fax (931) 473-5883 www.tnla.com Email: mail@tnla.com Published By Leading Edge Communications 206 Bridge Street, Suite 200 Franklin, Tennessee 37064 (615) 790-3718 Fax (615) 794-4524 Email: info@leadingedge communications.com Editors Dr. Bill Klingeman Dr. Amy Fulcher Associate Editors Dr. Karla Addesso Dr. Becky Bowling Dr. Nick Gawel Dr. Midhula Gireesh Dr. Nar Ranabhat TNLA Officers President Terri Turner Turner & Son’s Nursery 1st Vice President Jon Flanders Botanico, Inc. 2nd Vice President Osvaldo Lopez Ozzy’s Lawncare & Hardscape Services 3rd Vice President Sam Kinsey Kinsey Gardens Secretary-Treasurer Bryan Tate Mid-South Nursery Associate Director Todd Locke BWI Companies Ex-Officio Michael Gallagher Heather Farms Nursery Executive Director Louree Walker Associate Director Danae Bouldin

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