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.