Tennessee Greentimes - Summer 2024

The Official Publication of The Tennessee Nursery and Landscape Association

National Champion Tree Program An honor for Tennessee, a boon for the Nation

A Snapshot into Substrates Components Used by Tennessee Producers

Commodity Group Day at TSU College of Agriculture

The National Champion Tree Program: An honor for Tennessee, a boon for the Nation

A Snapshot into Substrates: Components Used by Tennessee Producers

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 ©2024 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.

Official Publication of The Tennessee Nursery and Landscape Association

Winterthur Viburnum

American Boxwood

Green Giant & Nigra Arbs

Sullivan Cypress

Gem Box Inkberry

Nova Taxus

Green Mtn. Boxwood

Sprinter Boxwood

Excelsa Arb

Uptight Boxwood

Green Gem Boxwood Steeds Holly Popcorn Viburnum

Hicksi Taxus Chicagoland Green Boxwood

Firelight Hydrangeas & Sprinter Boxwoods Densiformis Taxus Pragense Viburnum

Wintergem Boxwood Polar Gold Arb & Sky Pencil Holly

TNLA would like to thank the following companies for being Membership Sponsors Arboras, LLC.

GOLD Membership Sponsors

Barky Beaver Mulch & Soil Mix, Inc.

BASF

Blankenship Farms and Nursery

Botanico, Inc.

BWI of Memphis

Cam Too Camellia Nursery, Inc.

Delta Mulch and Materials, LLC

Drees Plant Wholesalers

Enviro-Scapes, LLC

Flower City Nurseries

Mid-South Nursery

NYP Corp.

Randall Walker Farms

Riverbend Nurseries, LLC

Swafford Nursery, Inc.

Swift Straw Tennessee 811

Tennessee Valley Nursery, Inc.

Turner & Sons Nursery

Warren County Nursery, Inc.

Youngblood Farms, LLC

SILVER Membership Sponsors

3F - Flanders Family Farm

Dayton Bag & Burlap Co.

Carpe Diem Farms

Cherry Springs Nursery

Kinsey Gardens, Inc.

Mid-South Nursery

Mike Brown’s Wholesale Nursery, LLC

Old Courthouse Nursery

Rusty Mangrum Nursery

Samara Farms

Scenic Hills Nursery

Woodbury Insurance Agency

It’s BIG PLANS AHEAD

summertime and your TNLA Board is hard at work for you. We are developing a new online job board which you can visit at https://www.tnla.com/careers/ If you have an entry that you want to submit, contact the TNLA office. Currently, it is being offered as a free service for TNLA member organizations only. We are also putting together a new buyer’s guide. It’s been over 10 years since we last published one. This year it will be both digital and in print. I want to take this opportunity to thank all of you who attended the TNLA Field Day at TSU’s Otis Floyd Nursery Research Center. There was a lot of good information sharing. For our members and chapter in East Tennessee don’t forget about our Field Day at The University of Tennessee coming up on June 27th from 8 am – 4:30 pm at UT Gardens. Contact Executive Director Danae Bouldin to sign up as an attendee or sponsor.

Save The Date! Next Fall our TNGRO trade show returns on October 23–24, 2025, at the Farm Bureau Expo Center in Lebanon, TN (visit at https://tngro.com/). Unfortunately, fall dates in 2024 were not available, but we have entered a three-consecutive year contract with the Expo Center beginning in 2025. We are excited about the future of TNGRO and had positive feedback from many vendors in 2023. Stay tuned for more to come.

We are always looking for members to serve on the board of directors or on select committees. If you are interested in serving your industry in any capacity, please contact one of our current Board members: Jon Flanders, President; Osvaldo Lopez; 1st Vice, Sam Kinsey, 2nd Vice; Trista Pirtle, 3rd Vice; Bryan Tate, SecretaryTreasurer; Todd Locke, Associate Director; Terri Turner, Ex-Officio or the TNLA office. Thank you for all you do to make the world a better place.

Jon Flanders TNLA President

The Tennessee Greentimes is the official publication of The Tennessee Nursery & Landscape Association, Inc.

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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 Jon Flanders Botanico, Inc. & 3F - Flanders Family Farm

1st Vice President

Ozzy Lopez Ozzy’s Lawncare and Hardscape Services

2nd Vice President

Sam Kinsey Kinsey Gardens

3rd Vice President

Trista Pirtle

Pirtle Nursery

Secretary-Treasurer

Bryan Tate

Mid-South Nursery

Associate Director

Todd Locke BWI of Memphis

Ex-Officio

Terri Turner

Turner & Sons Nursery

Executive Director Danae Bouldin

Commodity Group Day at TSU College of Agriculture

TNLA attended the Commodity Group Day at TSU College of Agriculture. Our Executive Director represented TNLA by explaining how we serve the industry and what we can offer students. Offering scholarships, informing students of TNLA, and collaborating with TSU are a few ways our association is investing in the youth of our industry. We look forward to more events like Commodity Group Day, where we can inform and recruit students.

An honor for Tennessee, a boon for the Nation The

By Jaq Payne, National Director of the Champion Tree Program

In TREE PROGRAM NATIONAL CHAMPION

California, 2,500 miles away from Tennessee, a forest of redwood trees has been growing steadily for over two millennia. Deep within this forest, the tallest tree recorded by the Champion Tree Program stands, with an entire ecosystem hidden and thriving in its massive canopy. This gargantuan Coast Redwood (Sequoia sempervirens), known as Lost Monarch (Fig. 1), clocks in at an unfathomable 321 feet tall. That’s 21 feet taller than a football field is long (minus the end zones). That’s 16 feet taller than the Statue of Liberty atop her pedestal. It’s also as tall as 64.2 Dolly Partons stacked on top of each other. Although most foresters don’t use “Dolly Partons” as a unit of measurement, the National Champion Tree Program is seeking new ways to engage the creative minds of the public and convey the majesty of these gentle giants.

The Champion Tree Program keeps the record of the largest trees in the United States of America. It started in the early 1940s when American Forests Magazine published an article penned by Joseph L. Stearns, calling for the recognition and protection of the largest trees in the country. He is pictured in the magazine, standing next to the burned remains of what was once the world’s largest Tulip Poplar (Liriodendron tulipfera) (Fig. 2), marveling at the wonder of its size and the tragedy of its loss due to the careless mistake of a couple hunters seeking refuge in the tree from the winter chill. American Forests heartily endorsed this proposition of finding and preserving America’s largest trees, encouraging readers to send in the location and size of the large trees they were aware of. “Such a conservation activity, it is believed, will have incalculable benefits, not only in stimulating greater tree appreciation, but in establishing a nation-wide laboratory for tree and forestry studies by future generations.”

The University of Tennessee is a natural fit for the future of this program. In mid-2023, the decision was made to transfer the program from American Forests to the University of Tennessee Knoxville,

School of Natural Resources and a national search was conducted during the summer of 2023. As the outcome of that search, I was selected to be the National Champion Tree Program Leader. This is an honor both for the University of Tennessee and for our state – Tennessee is home to the heart of the deciduous forest, and a great many people across the state are passionate about our beautiful trees. My name is Jaq Payne (Fig. 3), and I have had the joy, pleasure, and challenge of running the state of Tennessee Champion Tree Program (as featured in the Winter 2021 issue of Tennessee GreenTimes) for the past couple years, and my vision for the future of the National Champion Tree Program is clear and bright.

These trees are remarkable, not just for their size but for their contributions to our community. Some stand in graveyards, taking in the echoes of the pain of human loss with their silent stature, moving on a timescale that we can scarcely understand. Some of these marvels of nature are found in urban backyards, farmlands, and as with Tennessee’s State Champion Bald Cypress (Taxodium distichum), in the middle of a lake accessible only by kayak (Fig. 4). Not only does documenting these trees provide data that we can use to better understand tree morphology and physiology, but the experience also yields a wealth of cultural data – How do humans interact with and think about trees? What types of people have access to these trees? How do we increase the amount of people that are able to draw strength and peace from their connection with nature?

This re-imagining of the Champion Tree Program has three main pillars: Conservation, Information, and Education. First, conservation: 53 out of the 563 National Champion Trees, approximately 9% of the currently represented species, are listed on the IUCN Red List as Near Threatened, Vulnerable, Endangered, Critically Endangered, or Extinct in the wild. One such specimen is the National Champion Quercus tomentella, which is listed as endangered in the IUCN Red List.

Fig 4: Jaq kayaking to TN Bald Cypress Champion. Photo by Kayla Stuart

Fig. 3: Jaq Payne. Photo by Taryn Ferro, Aw Snap Photography

Fig. 1: Lost Monarch Sequoia sempervirens. Photo from National Champion Tree archives, by permission of American Forests.

Fig. 2: Joseph Stearns with Liriodendron tulipifera. Photo from American Forests Magazine, shared with permission.

A photo from American Forests shows the tree’s impressive stature (Fig. 5). Preserving the genetic material of these specimens, collecting seeds, propagating seedlings with partners across the country, and even cloning trees when it is safe and possible to do so, could have far-reaching implications in the world of tree preservation. Some of these species do not exist in any ex-situ collections, so ensuring that these species are represented in botanical gardens and arboretum is not only a priority for direct conservation, but also for engaging the public in recognizing these species and their value.

Next, information: With a strong national program, we are able to invest more in accurate measurement techniques and making sure that our State Coordinators and those who help them are trained correctly in how to measure trees. This goal is achieved through the help of the National Cadre of Tree Measurement Experts, which was started in the mid 2010’s by American Forests and a group of math and tree experts. By ensuring that we have key data that is as accurate as possible, we will be able to use this information to move toward the original 1940’s vision for the program: to serve as “a nationwide laboratory for tree and forestry studies by future generations.” This is one of the reasons that the University of Tennessee, a landgrant university lauded for its research, is the perfect home for the future of the Champion Tree Program. We also have the benefit of UT Extension, the hands of the university reaching out into the community, disseminating the empirical research being performed.

Finally, education: we are positioned to be able to use the information that we gain about these trees, along with what we learn from our focused conservation efforts, to help educate the public about the importance of trees. Large, mature trees like these contribute to our communal well-being and are vital components of a healthy, vibrant ecology in the greenspaces around us. By communicating the value of these trees, we will change hearts and minds, shift priorities, and expand nationally the focus of tree conservation work beyond just the simple planting of seedlings and young trees. We seek to fully embrace and instruct about the maintenance and protection of trees, whether they are Champions or not.

Fig 5: Quercus tomentella (endangered)

Fig 6: Sitka spruce. Photo by Brian Kelley, Gathering Growth Foundation, with permission from American Forests.

Fig 7: Solanum erianthum (potato tree), the shortest National Champion tree species (Texas specimen).

Many of the Champion Trees are near the end of their natural lives, having reached their highest heights and now are entering a state of decline. We must ensure that the public is educated on the importance of hiring certified arborists to maintain and sometimes remove these massive specimens when it is no longer safe for these sentinels to stand around people and property. Balancing the need for safety with the massive impact these trees have on their environment is a challenging endeavor. However, when certified arborists are engaged in making those assessments and property owners are helped to better understand their trees, we can more fully honor the life cycle of these distinguished tree specimens and find creative ways to utilize the wood that may be reclaimed from their timely or necessary removal.

It’s been said that the future is the past altered by the present. In this moment, the choices that we make will affect not only our immediate descendants, but their descendants and beyond (Fig. 6, Sitka Spruce photo courtesy of Brian Kelley, Gathering Growth Foundation, with permission of American Forests). As I imagine the future society that we are building right now, the natural world that we are borrowing from our greatgreat-grandchildren, I am heartened by the passion that Champion Trees evoke. Even our smallest Champion Trees, like the 9-foot-tall Potatotree (Solanum erianthum) in Texas (Fig. 7, courtesy of National Champion Tree archives), are beloved and held in high esteem by tree lovers across the country. By honoring these giants of their kind and by advocating for their protection, maintenance, and recognition, we are speaking directly to the people living on this land a hundred years from now. Letting them know that “We saw the immense value of these members of our ecological community, and we did our best to ensure that you get to enjoy their presence, too.”

More information about the National Champion Tree Program can be found at https://nationalchampiontree.org or by emailing contact@nationalchampiontree.org Nominations will reopen to the public in January 2025.

A SNAPSHOT into SUBSTRATES

Components Used by TENNESSEE PRODUCERS

By Walker Harrell 1, James S. Owen Jr.2 , Alicia Rihn 3, Karl McKim 1, Amy Fulcher 1

1University of Tennessee, Department of Plant Sciences, 2USDA-ARS Application Technology Research Unit, 3University of Tennessee, Department of Agricultural and Resource Economics

This is part one of a two-part series reviewing substrate components and their costs in 2023 – 2024.

Container substrate, what we often call potting mix, is a mixture of organic and inorganic soilless components that include pine bark, peat, wood fiber, coir, compost, and sand that are amended with lime, mineral nutrients, or pesticides (Figure 1).

Components: organic and inorganic materials that compose the bulk of the substrate volume, and along with container height, influence its physical properties

Amendments: agrochemicals that are added to a substrate to adjust or maintain pH, provide nutrients, or control pests. Amendments can influence the substrate solution’s electrochemical properties, for example pH, electrical conductivity and oxidation state.

The substrate anchors plants, provides a reservoir for water and mineral nutrients, and ensures adequate oxygen for root growth. The substrate mixture and potting method directly determine the quantity of substrates used, their static physical properties (total porosity, container capacity, air space, and bulk density), and chemical properties (pH, electrical conductivity).

Static Physical Properties characterize substrates and allow them to be compared:

• Total Porosity is total pore space; air space plus container capacity

• Container Capacity is the maximum water holding capacity; % volume at drainage; total porosity minus air space

• Air Space is the maximum pore space filled with air; determined at container capacity; total porosity minus container capacity

• Bulk Density is the dry weight divided by the total volume of the sample

When mixing substrate, one part plus one part does not equal two parts; but instead forms a unique substrate with its own distinct physical and chemical properties. The resulting blend may be fluffy, resisting compaction, or dense in which the substrate can become tightly compacted at the time of potting, or a combination of fluffy and dense.

Figure 1. Substrates must contain several components and amendments to grow healthy plants in a soilless system.

Pine Bark

Fertilizer Lime

Coconut Coir Sand

The substrate in the container and the cultural practices used will directly affect water and nutrient use, crop performance, and shipping weight. Substrate consistency is the key to success. For a given crop, the right combination of substrate, fertilizer, and irrigation scheduling needs to be determined. Any changes in suppliers, substrate components’ appearance, substrate’s chemical properties, measuring methods, or mixing methods may result in needed changes to the substrate blends or production practices. Consistency requires continued communication with allied suppliers and personnel. Simply put, a consistent and well-understood substrate is important for profitable production.

Pine Bark

The main substrate component used in southeastern US nurseries is pine bark from Loblolly or longleaf pine (Figure 2). Aged or fresh pine bark is hammer milled or screened to less than half an inch. Aged pine bark, also referred to as stabilized, is a result of bark being wind-rowed for 1 to 6 months. Aging allows the bark to break down into smaller particles. Harrelson et al. (2004), Laiche (1974), and Handreck and Black (1994) reported that aged pine bark produced larger plants than fresh pine bark. The larger plants were likely a result of increased water and nutrient storage. Original bark particle size, age, moisture content, processing technique, and screen size determine the texture or amount of fine, medium, and large particles. Bark texture will govern the substrate’s physical properties. A rule of thumb is that a greater proportion of smaller particles will increase water retention and decrease air space; whereas a greater proportion of coarse particles will decrease water retention and increase air space. The age of the bark also determines starting pH and the substrate’s resistance to a change in pH. The pH of pine bark is between 4.0 and 5.0 but can vary based on age and wood content.

Pine bark will also contain wood or sand with neither being detrimental to crop production. Remember the mantra – consistency is key! Consistency includes the composition of delivered bark including wood and sand. A grower can receive up to 10% sand by volume if bark is wind-rowed or stored on the ground (Dr. Brian Jackson, personal communication). Softwood, either intentionally or inadvertently through the milling process, will comprise on average 10% (5% to 25% range) by volume of the bark you receive (Dr. Brian Jackson, personal communication). Softwood will become darker in color over time as it becomes stained from bark tannins making it unnoticeable to the user and consumer. Unprocessed softwood has less lignin than bark, which can affect the rate of particle breakdown and substrate pH.

Bark consistency can vary due to variable feedstock being provided to the supplier, moisture content at the time of supplier processing, or the storing process. This variability can be addressed by purchasing, or on-site screening, bark into two or three sizes or textures: fine, medium and coarse. These textures can then be recombined in exacting proportions at the time of blending to better control the substrate’s physical properties.

If pine bark will be stored at the nursery for prolonged periods it should be in piles less than six feet tall and turned and irrigated regularly to prevent the bark from becoming anaerobic or lacking oxygen. Anaerobic bark will be dry, have a low pH, and high electrical conductivity. Improperly aged bark that has become hydrophobic is unusable in its current condition.

Dolomite, or dolomitic lime, is commonly used to amend pine barkbased substrates. If adding lime, granular micronutrients should also be added. In addition to improperly stored bark becoming hydrophobic, bark can become hydrophobic after potting, repelling water and decreasing water retention (Airhart 1978; Pokorny 1979). Incorporating commercially available surfactants at the time of potting can prevent this issue. If observed during production, drenching with a liquid surfactant can break surface tension, allowing bark to rewet. During irrigation experiments at the University of Tennessee, a 75% pine bark 25 % peat moss substrate became hydrophobic during production of hydrangeas (Hagen et al. 2014). Substrate components that are less prone to becoming hydrophobic may be more suited to conservative irrigation schedules, those that allow the substrate to dry considerably between irrigation events, than other substrate components.

Figure 2. Pine bark is the foundation of container substrates in Tennessee. It may contain wood and sand, either intentionally, or through the processing or storage.

Peat Moss

Canadian Sphagnum peat is a fibrous substrate component commonly used alone or in combination with bark to produce liners, hydrangea, azalea, and other pH- or water-sensitive nursery crops. Its prominence in horticulture as the ‘gold standard’ is due to its unmatched physical and chemical properties. Peat is shipped in compressed towers or bales requiring specialized equipment before use. Peat increases water retention in bark-based substrates. Peat also has a naturally low pH of 3.0 to 4.5. However, like pine bark, peat can become hydrophobic (Michel 2015) and difficult to rewet. Therefore, peat should be stored moist in sealed pails, or have water added, to ensure fluffed peat does not dry out. Surfactants and dolomitic lime are typically applied at the time of mixing the substrate when using peat.

Layers of Sphagnum peat develop from slow-growing Sphagnum moss over thousands of years in Canadian bogs or wetlands (Figure 3). As peat accumulates beneath the living layer of moss, atmospheric carbon is captured and stored in the ground in a semi-permanent form. When peat is harvested, the bog and harvested peat are susceptible to decomposition that releases carbon into the atmosphere.

Horticultural use of peat has been featured in the national media. Peat, by definition, is a non-renewable resource, requiring >100 years to replenish. However, according to Dr. James Altland, United States Department of Agriculture, only 0.03% of the 294 million acres of Canadian peatlands, and according to Clarke and Rieley (2019) just 0.05% of worldwide peatlands are harvested for horticultural uses that produce edible, ornamental, and forest seedlings providing social, environmental, health, and economical benefits.

Production-related concerns surrounding peat today are availability and cost. Weather has repeatedly prevented adequate harvests to meet industry demand in North America. The lack of readily available peat as a substrate component will require the industry to rethink their dependence. In many cases, nurseries are purchasing premade substrates that include peat from allied suppliers or are exploring alternatives. In response, the horticultural industry is considering substrate components that can extend peat supplies, while still relying on peat as a substrate ingredient.

Other Substrate Components

Wood fiber is a renewable, abundant, and available substrate component. Wood fiber is created from defibrating softwood wood chips using a twin-disc refiner, extruder, or hammermill (Durand et al. 2021). Extruded or refined fiber undergoes heating during processing which can increase stability. Wood fiber is typically shipped in compressed bales that require specialized equipment before incorporation into substrate mixes. Wood fiber can vary in size and shape depending on processing and user preference. A wide range of wood fiber physical properties from differing processing techniques have been reported to improve water retention as well as aeration of peat-based substrates (Durand et al. 2021; Jackson 2018), demonstrating the diversity of the product. We hypothesize that adding fiber would be like adding finer bark to a barkbased mix, but not increase water retention as much as a peat or compost. However, wood fiber could decrease water flow through a coarser pine bark substrate. With ever-increasing adoption of wood fiber throughout the horticultural industry, more research is needed for wood fiber use in pine-bark based substrates for use in nursery crop production.

Coir refers to coconut pith, which is a by-product of processing the outer husks of coconut palms ( Figure 4a & b; Schmilewski 2009).”

Figure 3. Spaghnum peat used in the U.S. horticulture industry is harvested from Canadian bogs.

Photo taken at Berger, Saint-Modeste, Québec, Canada.

Figure 4a. Coir comes compressed in bricks that must be broken apart and hydrated.

Figure 4b. Coir after “fluffing.”

Brackish or salty water is commonly used for processing, which causes the pith to have high sodium or potassium levels (Agarwal et al. 2023). Leaching the sodium with freshwater is required to prepare the pith for horticultural use. The pith can also be pH buffered with calcium nitrate. Use of freshwater and calcium nitrate increases the cost to produce a high quality, production-ready horticultural substrate. Coir is typically shipped in compressed bricks that require water and time to decompress or specialized equipment to mechanically “fluff” before use. Research at the University of Tennessee and elsewhere has shown that coconut coir has tremendous water holding capacity and that much of the water is “plant available”, when compared to peat or pine bark (Basiri Jahromi et al. 2020). Additionally, coir does not become hydrophobic when dry. However, coir is not a direct replacement for peat. Coir has a neutral to high pH and different physical properties, and like all new components requires in-house evaluation before adopting nursery-wide.

Compost is a viable, routinely used component of substrate as a smaller proportion of the total mixture. Compost usually has a neutral or high pH and will typically increase water retention. The compost feedstock; the process and time of composting and receiving, storing, and using the compost; must be consistent to ensure a reproducible, quality crop. Vermicompost, or worm castings or manure, is a compost that is locally available in Tennessee.

Lastly, washed builder’s sand is added to substrate to add weight, although that does not appear to result in reducing container blow over. Sand was once believed to increase drainage. We now know that sand will fill in larger pores to aid in water moving more slowly through the container profile and thus more completely wetting the substrate (Bilderback et al. 2005). Fine sands may clog substrate pores and retain too much water.

Chemical Amendments

Many nurseries also amend their substrates with dolomite or lime, micronutrients, controlled release fertilizer, or pesticides. The addition of dolomite or lime increases and helps maintain the substrate pH. Liming can decrease micronutrient availability. Granular micronutrients are typically added when using lime or dolomite. Testing irrigation water is important given that the water source may be alkaline (greater than 100 ppm) or contain mineral nutrients such as calcium and magnesium resulting in continual liming or adding essential nutrients when irrigating. Controlled release fertilizers are coated or otherwise include a barrier that releases mineral nutrients gradually, fertilizing plants over a period of months instead of agricultural-grade fertilizers, which generally release macro- or micro- nutrients over a period of weeks or even days. In rare instances, the controlled release fertilizer coating can be compromised when incorporated into the substrate depending on mixing equipment, substrate components, and mixing time, which results in more nutrients being released than expected at the time of potting. Pesticides are most often added to control insects such as fire ants or root rots.

Conclusions

A wide range of organic and inorganic components are used in container substrates. Understanding substrate physical and chemical properties and how these properties can change with changing feedstocks, storage conditions, and storage duration is critical to managing substrate

consistency and making needed adjustments to production practices to produce uniform, high quality crops. All substrate components, including alternatives promoted to replace peat, have their own carbon, water, energy, or environmental footprint. This article highlights the potential to use a range of products, often by-products of other forms of agriculture, in container substrates and the need to develop a system by which substrates can be fairly evaluated and compared.

References and Resources for Additional Reading

Agarwal, P., S. Saha, and P. Hariprasad. 2023. Agro-industrial-residues as potting media: physicochemical and biological characters and their influence on plant growth. Biomass Conversion and Biorefinery 13:9601-9624.

Airhart, D.L., N.J. Natarella, and F.A. Pokorny. 1978. Influence of initial moisture content on the wettability of a milled pine bark medium. HortScience 13:432-434.

Basiri Jahromi, N., A. Fulcher, F. Walker, and J.E. Altland. 2020. Optimizing substrate available water and coir amendment rate in pine bark substrates. Water 12(2), 362.

Bilderback, T., S. Warren, J. Owen, and J. Albano. 2005. Healthy substrates need physicals too. HortTechnology 15(4):747-751.

Durand, S., B. Jackson, W.C. Fonteno and J.-C. Michel. 2021. The Use of Wood Fiber for Reducing Risks of Hydrophobicity in Peat-Based Substrates. Agronomy. 11(5), 907;

Fields, J., B. Jackson, and W. Fonteno. 2012. Pine Bark Physical Properties Influenced by Bark Source and Age. Acta Horticulturae. 10.17660/ ActaHortic.2013.1014.96

Hagen, E., S. Nambuthiri, A. Fulcher, and R. Geneve. 2014. Growth and water consumption of Hydrangea quercifolia irrigated by on demand and daily water use irrigation regimes. Scientia Horticulturae 179:132-139.

Handreck, K.A. and N.D. Black. 1994. Growing Media for Ornamental Plants and Turf. Univ. New South Wales Press, Randwick, Aust.

Harrelson, T., S.L Warren, and T.E. Bilderback. 2004. How do you manage aged versus fresh pine bark? Proc. SNA Res. Conf. 49:63-65.

Jackson, B.E. 2018. Substrates on Trial: Wood Fiber in the Spotlight. Greenhouse Management, September, 38(9):52-56. https://www.greenhousemag.com/ article/substrates-on-trial-wood-fiber-in-the-spotlight/

Laiche, A.J. 1974. Pine bark growing media-fertility studies for the production of container-grown ornamentals. MAFES Res. Highlights. 37:1-3

Michel, J.-C. Wettability of Organic Growing Media Used in Horticulture: A Review. Vadose Zone J. 2015, 14.

Pokorny, F.A. 1979. Pine bark container media – An overview. Comb. Proc. Intl. Plant Prop. Soc. 29:484-495.

Schmilewski, G. (2009) Growing medium constituents used in the EU. International Symposium on Growing Media 2007(819):33–45

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