Plastic Plant Pots: Planting is Green, But so is Keeping the Use of Plastics to a Minimum

By Wendy Diaz, EMGV

The Problem

It seems plastics polluting the environment has reached a crisis level. I first heard about floating plastic waste islands in the middle of the Pacific Ocean many years ago and microplastics in cosmetics finding their way into the largest freshwater bodies in the world–the Great Lakes. And now more than ever, the issue is frequently in the news of how plastics are ubiquitous because they are not biodegradable and are harming wildlife and the environment [1]. Apparently, we unintentionally ingest a plateful of microplastics (less than 5 mm in diameter) per year[2]. Some sad and alarming photos were recently published by the BBC of birds living with plastic waste and other garbage[3]. Local organizations like Don’t Waste Durham want to start banning Styrofoam,[4] and the Haw River Assembly uses innovative ways to keep plastics out of our waterways like a Trash Trout™, which is a stormwater litter trap.[5] I even found in my yard a small bird nest that had fallen to the ground after a summer thunderstorm that was made with black and green plastic netting.

Trash Trout stormwater litter trap prevents plastics and other human-made trash from entering a main waterway in NC. (Image credit: Emily Sutton, Haw Riverkeeper. Used with permission courtesy of Haw River Assembly)

In fact, in the United States, plastics production contributes 232 million metric tons of greenhouse gas emissions per year, and by 2030 plastics production is expected to outpace all US coal plants’ greenhouse gas emissions. There is even a newly-recognized geological time interval called the Anthropocene or ‘Age of Man’ to acknowledge the extensive changes to processes and conditions on Earth made by humans that is distinct from the Holocene Epoch, which followed the Age of Continental Glaciation, and includes such phenomena as the ‘global dispersion’ of plastics contributing to a new distinctive strata according to the Subcommission on Quaternary Stratigraphy (http://quaternary.stratigraphy.org/working-groups/anthropocene/).

My efforts to reduce our use of single use plastics such as bags, containers, and wrapping by buying in bulk and purchasing less wasteful products is improving, but plastic is the material of choice for packaging, and it is hard to find alternatives. We have grown accustomed to the convenience of these cheap disposable containers and packaging in our throwaway society. In the United States, the mass production of plastics has skyrocketed from less than a half a million metric tons by weight in 1960 to over 32 million metric tons in 2018[6]. In 2019, the United States, as the largest producer of plastic waste, generated about 42 million metric tons, and 1 to 2 million metric tons of that ended up leaking into the oceans and environment[7].

As gardeners, there are a few things we can do though to lessen the environmental impact of plastics. I usually accumulate about a wheel barrow full of plastic pots of both small and large sizes and a few trays each year when I buy annuals for my flower pots, vegetables for my tiny garden, and perennials and trees for my landscape. This may not be as much of the total plastic I purchase throughout the year for such items as yogurt, shampoo, laundry detergent, garbage bags etc., but plastic pots can be large and do contribute to the overall increase in plastics in the waste stream of our society that usually ends up in landfills (73 % of all plastic waste)6 which is bad for the environment [8]and contributes to greenhouse gas emissions.

Collection of plastic pots from my 2022 spring planting season.
(Image Credit: Wendy Diaz)

Worldwide, only 9 % of plastic waste is recycled[9]. In 2019, the United States only successfully recycled 4%, although an equally small portion of 4% was mismanaged or counted as uncollected litter. The US has an extensive waste management system that includes incineration of 19% of the plastic waste[10]. Everyone has heard of the 3 Rs, Reduce, Reuse (repurpose) and Recycle, but it is worthwhile to remind everyone of the waste management hierarchy in that reducing is better than reusing and reusing is better than recycling and all of these are better than throwing them in the garbage and worse of all littering.

Partial Solutions

The best option for gardeners is to reduce and avoid purchasing plants in plastic pots in the first place. Then we don’t have to find a place to dispose of them so they don’t end up in our waterways and eventually into the oceans. But until there are new policies for and innovations in the packaging and container industry such as Extended Producer Responsibility schemes or EPR,9 there are only a few things we gardeners can do to not add to this global problem. 

Reduce

Instead of using plastic pots to start our seeds, one strategy we can employ is to use the Soil-Block method and tools. This technique involves making your own soil block forms using wet seed starting mix where seedlings ‘self-prune’ by air between the soil blocks instead of becoming root bound in traditional plastic pots. The added benefit is that they more quickly adjust to transplanting and establish quicker because the seedling’s roots don’t encircle a pot and they don’t have to learn to unfurl.[11]

(Left to right) Various handheld soil blocking tools; the white circular tool on the top right is a handmade version. These are readily available online. Prepared soil-blocks with seeds in their reusable propagation tray. (Image credits: Penn State Extension and Collin Thompson, Michigan State University Extension)

Reuse

Plastic pots do not have to be a ‘single use plastic’ container and we can wash them and donate them for reuse. I also save both small and large plastic pots for my personal use to:

  • start my own cuttings of plants or seeds;
  • transplant ‘volunteer’ tree seedlings for my tree nursery;
  • pot perennials in the fall that I have split for pass-a-long plants for neighbors and friends,
  • scoop soil or worm castings from bags while planting,
  • collect and store small pebbles I find while weeding for future use, and,
  • place over tender plants for frost protection[12].

Nevertheless, I always end up with more than I can reuse so I donate them to our own local Briggs Avenue Community Garden. Sometimes, the Master Gardener plant sale needs certain size pots for their annual spring plant sale fundraiser. Your local nursery may also take your plastic pots for example the Durham Garden Center has a ‘Give and Take’ table near their checkout where home gardeners can leave their pots. Our pervasive use of plastics is even influencing artists[13] such as Susie Ganch whose work explores “the interconnectedness of the human experience and the environment.” Although, not practical unless you know an artist who works in waste plastics media, it is an interesting way to repurpose single use plastics.

Recycle

In Durham, where I live, it can be confusing of where you can recycle plastic plant pots. At the time of writing this article, our local Durham County Solid Waste Convenience Site did not recycle plastic pots, and I was told they throw them in the trash dumpster so they can be transferred to the landfill. Whereas, the County of Durham allows for the recycling of plastic pots, even black ones, according to the online tool Waste Wizard[14] as shown below on their online site.  (Black pots can be a problem for some local facilities because they contain pigments which make them undetectable to the sorting machinery.) Local big box stores advertise that they recycle plastic pots but when I visited by local store the staff was unaware of plastic pot recycling.

Plastic plant pots and trays are allowed in the biweekly curbside reclycling bins in Durham County based on the Waste Wizard tool on the Durham County Website. (Image Credit: Durham County NC) https://www.dconc.gov/county-departments/departments-f-z/general-services/solid-waste-recycling-and-litter-control

Nevertheless, the City of Durham will take them in their recycle bin and most plastic plant pots are made from the most common and most ‘valuable’ polymers of plastic. The black plastic pots are labeled ‘2 HDPE’ for High-Density Polyethylene and hopefully it is recycled and used in the manufacture of picnic tables, fencing and detergent bottles for example. The colored pots are generally labeled ‘5 PP’ for Polypropylene and are stiff and can be used in the manufacture of battery cases and bins. The small multi-plant trays labeled ‘6 PS’ for Polystyrene are weaker and can be recycled into more packaging. Remember to rinse the soil out before you put the pots in the recycle bin; clean plastic pots have a better chance of being recycled and not discarded during the sorting process.

What gardener doesn’t want to make the world a little ‘greener?’ You can do it by planting more plants and by not throwing away the containers they come in. Let’s not force the birds to do our reusing for us.

Bird nest made with black and green plastic found in my yard in July 2022.
(Image Credit: Wendy Diaz)

Notes


[1] https://www.bbc.com/future/article/20220711-do-single-use-plastic-bans-work

[2] https://graphics.reuters.com/ENVIRONMENT-PLASTIC/0100B4TF2MQ/index.html

[3] https://www.bbc.com/news/science-environment-62407026

[4] https://www.newsobserver.com/news/local/counties/durham-county/article212683574.html

[5] https://hawriver.org/trash-trout/

[6] https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/plastics-material-specific-data; https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/national-overview-facts-and-figures-materials#Generation

[7] https://earth.org/plastic-pollution-statistics/

[8] https://www.bbc.com/news/science-environment-42264788

[9]https://www.oecd.org/environment/plastic-pollution-is-growing-relentlessly-as-waste-management-and-recycling-fall-short.htm

[10]https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/plastics-material-specific-data

[11]https://www.johnnyseeds.com/growers-library/methods-tools-supplies/seed-starting-transplanting/soil-block-makers-eliot-coleman.html

[12] https://www.trvst.world/waste-recycling/recycle-plant-pots/

[13] https://susieganch.com/section/343666-Recent-Exhibitions.html

[14] https://www.durhamnc.gov/878/Waste-Disposal-Recycling-Center

Learn more about leading a less wasteful lifestyle by exploring the following links:

  1. Plastic Free July by Plastic Free Foundation https://www.plasticfreejuly.org
  2. Don’t Waste Durham  http://www.dontwastedurham.org
  3. Keep America Beautiful

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Kelly Norris to Speak at Durham Garden Forum September 20 Lecture

Want to learn more about an ecologically sound vision for the next generation of home gardens?  If so, join the Durham Garden Forum (DGF) online on Tuesday, September 20, at 7:00 pm to hear Kelly Norris, acclaimed horticulturist and author, speak at the fall 2022 kick-off of the DGF 2022-2023 lecture series.

Norris is the author of New Naturalism:  Designing and Planting a Resilient, Ecologically Vibrant Home Garden.  He will discuss converting turf to vibrant garden settings to increase biodiversity.  He will use his personal half-acre garden as an example.  It contains more than 120 plant species and a growing list of birds and insects.

Norris is an award-winning plantsman, and in addition to authoring several books, his work in gardens has been featured in The New York Times, Better Homes and Gardens, Organic Gardening, Fine Gardening, Garden Design, and in radio, television, and digital media. He is the former director of horticulture and education at the Greater Des Moines Botanical Garden and was a 2015 Chanticleer Foundation fellow. Norris’s gorgeous aesthetics “mimic the wild spaces we covet,” and his natural planting style “supports positive environmental change and leads to a more resilient space.”1

The Durham Garden Forum is an informal group that meets once a month to enrich gardening knowledge and skill.  Meetings are on the third Tuesday of the month from 7 – 8:30 pm.  Meetings will be via Zoom through the end of 2022.  Members have access to a video library of presentations, and they also receive discounts at Durham Garden Center and For Garden’s Sake

Durham Garden Forum (DGF) memberships cost $25 per year.  You can access the membership form here (scroll down).  If you are a DGF member, you will receive invitations to register for each month’s meeting. 

Times and topics for upcoming 2022 DGF lectures are:

  • October 18, 2022; 7:00 pm – Leave the Leaves
  • November 15, 2022; 7:00 pm – Direct Seeding Spring and Summer Flowers
  • December 13, 2022; 7:00 pm – Proper Selection and Use of Growing Media

You can choose to attend individual lectures for $10 each.

Questions?  Contact durhamgardenforum@durhammastergardeners

https://durhammastergardeners.com/tag/durham-garden-forum/

Notes

1–New Naturalism: Designing and Planting a Resilient, Ecologically Vibrant Home Garden. Cool Springs Press.

Pot Luck: A Wildlife Ecosystem in the Middle of a City?

By Mary Knierim, EMGV

The second installment of our series “Pot Luck: Adventures in Urban Container Gardening

Images Credit: Mary Knierim

A group of Durham County Master Gardeners recently partnered with a local business to create an urban garden with the purpose of teaching the community about container gardening. The Cocoa Cinnamon coffee shop at the intersection of Geer Street and Foster Street is close to downtown in a commercial district populated by bars, restaurants, apartment buildings, and offices. The very challenging location is exposed to full sun and surrounded by concrete and asphalt. Temperatures can range from colder in the winter to much hotter in the summer than our Zone 7b status typically suggests. Additionally, there is a large noisy building site across the street. The garden is planted in a variety of medium to large-sized metal containers on the street-side perimeter of the property. Some permanent year-round interest in the form of shrubs, grasses and perennials were planted in the fall of 2021. In the spring of 2022, more perennials and annuals were added. The plants are a mixture of native and non-native species. 1

As a photographer, I am always looking for a new project to tackle. As part of the team that worked on the project, I had photographed the Cocoa Cinnamon container garden in its various stages of planting and documented the work that was put into creating it. I then became curious about what kind of insects and wildlife might inhabit the space. Selfishly, I also wanted to improve some of my photography techniques. So one day I went to the garden. I walked around looking to see what was there.  Immediately, I saw quite a variety of bees. A lot of patience is required for nature photography, and so I ordered a coffee and sat and watched. Occasionally, I would get up and walk around the different containers. As I spent time observing,  I began to see tiny little insects as well as bees and butterflies. I photographed whatever I could see (or barely see – a magnifying glass would have been handy). When I got home I began to research what I had found.  After only two visits I have documented many insects, including all sorts of flies, beetles, bees, and butterflies. Lots of questions have emerged: Are these all native insects?  What is their function in relation to plants and other insects? Are they beneficial to our local area and the general ecosystem of the garden? Below is a list of common and Latin names of the insects (sometimes incomplete) and some brief information. Not surprisingly I found quite a few insects that were pests, but it is good to know what is in the garden in case some intervention is needed. You never know if the antidote to your problem also is residing in the garden.  For example, lady beetles feed on aphids. 

Interestingly, as the containers surround the patio seating area at the coffee shop, no one has reportedly been bothered at all by the insects. In fact many customers are rather pleased to see so many insects are attracted to the garden.

As we become more aware of how important insects and wildlife are in maintaining a healthy ecosystem, we hope to inspire folks to incorporate plants into their outdoor spaces. Maybe you would like to go out in your garden with a magnifying glass (or jeweler’s loupe) and discover a whole other world?

Since I only started this project in July, I probably missed some insects that are more prevalent in late spring/early summer. I hope to keep up with this project over the coming months. 

Note:  I have labeled this a wildlife garden as I hope to find other critters and perhaps some birds feeding on the sunflower seeds.

To see all the photos of insects in this urban oasis, go to the site listed below. Visitors will be able to view the gallery now through November 30, 2022.

https://knierim.smugmug.com/Cocoa-Cinnamon-Wildlife-Blog-Photos/

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Insect List 2022

Image Credit: Mary Kniernim

Common Bumble Bee (Bombas impatiens) Found widely across the eastern United States. An important pollinator for crops, feeds on a variety of flowers and trees. Nests underground.

Delta Flower Beetle (Scarab Trigonopeltastes delta) Native to the eastern United States.

Leafhopper (Graphocephala coccinea) Approximately 1/4” long, garden pest. They transmit Pierce’s Disease (commonly known as leaf scorch).

Fruit Fly (Tephritidae sp.) A pair of fruit flies. Larvae feed in or one soft-bodied fruits.

Cabbage White Butterfly (Pieris rapae) Common in gardens. Feeds on plants in the mustard (Brassicaceae) family.

Long-legged fly (Dolichopodidae sp.) 0.1-0.15″ beneficial insect.  Adults are predators of small insects such as aphids.

Small Carpenter Bee (Ceratina sp.) Solitary bees like this are also a great pollinators.

Spotted Lady Beetle (Coleomegilla maculata) Found throughout the United States.  Beneficial in the garden for eating aphids, scale insects, mealybugs, spider mites, and more.

Silver Spotted Skipper Butterfly (Epargyreus clarus) Very common pollinator in the United States. Prefers blue, red, pink and purple flowers never yellow.  Caterpillars feed on soybean crops.

Cocklebur weevil (Rhodobaenus quinqubpunctatus) Feeds on stem tissue of sunflowers, ragweed and cockleburs.  Not a significant threat to plants.

Horace’s Dusky Wing Butterfly (Erynnis horatius) Eastern United States. Found on dogbane, buttonbush, sneezeweed, goldenrod, peppermint, boneset and winter cress.

Eastern Cicada Killer Wasp (Sphecius speciosus) Eastern United States. A large solitary wasp. Beneficial for hunting dog-day cicadas which damage trees.

True Bug (Hemiptera order; genus and species unknown) Several species of true bugs live in North Carolina, including stink bugs. All have piercing and sucking mouthparts. Some are predatory insects.

Flea Beetle (Phyllotreta sp.)

Agricultural pest that feeds on leafy greens. Seen here on sweet potato vine but not a sweet potato flea beetle.

Fly (Diptera order; genus and species unknown)

Mason Bee (Hoplitis sp.) United States native bee. Solitary. Carry pollen on their backs. Excellent pollinators.

Snowberry Clearwing (Hemaris diffinis) Moth that mimics a bumblebee. Also known as hummingbird moth. Eastern United States. Pollinator garden insect.  

Blue-winged wasp (Scolia bubia) Beneficial insect. Two yellow spots on abdomen and blue-black wings. Predator of green June beetle larvae. Kills by stinging and laying eggs in the larvae (grubs). Upon hatching, young wasps cannibalize the grubs. 2

Pigweed Flea Beetle (Disonycha glabrata) Found in Eastern United States.  0.1-.28″ in size.  Feeds on pigweed and amaranth. Found at Cocoa Cinnamon on purple love grass.

Fiery skipper (Hylephila phyleus) Common garden butterfly.

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Notes:

1–To read more about the establishment of the urban container garden in downtown Durham, NC, see the first blog post in our series “Pot Luck: Adventures in Urban Container Gardening.” https://wp.me/p2nIr1-2jZ

2–This type of insect, whose larvae live as parasites that eventually kill their hosts (usually other insects), is known as a parasitoid.

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Resources and Additional Reading

North Carolina State University Extension has an incredibly extensive website on insects featuring photos, fact sheets, identification guides, entomology terms, and information on environmental stewardship.

https://gardening.ces.ncsu.edu/insects-2/

Check out Texas A&M University/Texas AgriLife Extension’s thorough guide to photographing insects. This presentation includes basic lighting and composition techniques all the way up to sophisticated information on advanced photography including shutter speeds and equipment options.

https://extensionentomology.tamu.edu/files/2020/02/Basic-insect-photography_shorter.pdf

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Specimen Spotlight: Hardy Ageratum

by Melinda Heigel, EMGV

Hardy ageratum making its debut this August in Durham’s Trinity Park. (Image credit: M. Heigel)

You know it’s late summer with fall on the way when you see the delicate blue to purple flowers of hardy ageratum (Conoclinium coelestinum) begin to emerge. Hardy ageratum has more common names than you can shake a stick at: blue boneset, blue mistflower, mist flower, and wild ageratum to name a few. Beauty is in the eye of the beholder when it comes to this wildflower, as some might consider this plant to be a mere invasive weed you often see growing along roadsides. But it can be right at home in your garden, offering great fall color and texture until the first frost. This plant also provides late-season nectar for pollinators–especially butterflies, and birds enjoy the seeds, too.

Hardy ageratum is a herbaceous perennial native to the eastern US and one of three native mist flowers in the US overall.1 The flowers are tubular in nature, resemble thistles, and grow in dense clusters called corymbs. These soft, fuzzy and showy flowers offer an etherial old-fashioned look. But make no mistake about this plant– it’s tough, reliable, and get can get assertive in the cultivated landscape. It spreads by rhizomes (underground stems that creep horizontally and give off roots and shoots) and is also self-seeding. Its enthusiastic growth habit makes it a great plant for naturalized areas, cottage gardens, or urban prairies. But don’t let its vigor deter you. It is also great as a back-of-the-border plant. And while that likely means some diligent “management” on your part, it is well worth the effort. You’ll enjoy roughly 2-3 months of continuous flowers. This late-bloomer has a clumping upright habit and typically grows 1.5′-3′ tall and up to 3′ wide.

(Above) Hardy ageratum (Conoclinium coelestinum) paired with the rich autumn color of sedum (Sedum sp.), and (below) two natives make a stunning combination when you plant hardy ageratum with pink muhly grass (Muhlenbergia capillaris) (Image Credits: Eva Munday CC BY-NC 4.0 and Susan Strine CC BY 2.0)

Growing Conditions and Care

Hardy ageratum prefers full sun to part shade, but full-sun conditions ensure the most abundant blooms and compact habit. These natives grow best in average, medium to wet but well-drained soils and grow all throughout North Carolina. They prefer fertile environments. Propagating these plants is easy; clump division in early spring is best. Also consider a springtime prune as well, again, to encourage a denser plant and reduce the need to stake later in the summer. These plants can get weedy if not cut back.

Hardy ageratum isn’t a plant you easily find these days unless your local nursery places an emphasis on native plants. These fall into the “pass-along plant” category, as these might be plants you get from a neighbor or a plant swap (and there is always that roadside ditch). You can, however, find seeds for this perennial wildflower online or at your local garden center. But don’t confuse hardy ageratum with its cultivated cousin Ageratum houstonianum. You can find these tender annual varieties in abundance for sale each spring and summer. The look is quite similar, but they tend to be shorter, more compact plants (usually 6″- 8″ tall) and grow in tight mounds, though some taller varieties are available. While they share the same preferences for growing conditions as the perennial hardy ageratum and also have a long bloom time, these annuals are often best for containers and front-of-the-border spots in your beds.

Two examples of the many choices of annual non-native varieties of ageratum that bloom from spring to fall. (Image Credits: Cathy DeWitt CC BY 4.0 and Mauricio Mercadante CC BY-NC-SA 2.0 )

Despite its propensity to be overzealous, hardy ageratum can be a solid addition to your landscape. A workhorse of a plant, it supports wildlife like beneficial insects and birds while at the same time managing to be deer and rabbit-resistant. Keep an eye out for it now through November and imagine what it might lend to your garden.

Notes

1–There are 3 hardy ageratums native to the US, and Texas is the only state where you can find them all. In addition to the our specimen spotlight Conoclinium coelestinum, there are also the betony-leaf mistflower (C. bentonicifolim) native only to Texas and the palmleaf mistflower (C. dissectum, formerly known as the C. greggii) native to Texas, New Mexico and Arizona. All perform well in Zones 7-11.

https://newswire.caes.uga.edu/story/5961/butterfly-attractor.html

Resources and Additional Information

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Visit North Carolina State University’s plant toolbox website for more details on hardy and annual ageratum

Native perennial: https://plants.ces.ncsu.edu/plants/conoclinium-coelestinum/

Non-native annual: https://plants.ces.ncsu.edu/plants/ageratum-houstonianum/

Missouri Botanical Garden’s website offers a through profile of hardy ageratum

https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=j870

For a finer look at the taxonomy changes for hardy ageratum formerly known as Eupatorium coelestinum, the University of Arkansas extension site outlines the journey of scientific classification

https://www.uaex.uada.edu/yard-garden/resource-library/plant-week/mist-flower-12-02-11.aspx

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