054-Plastic Nursery Pots – Greening Up The Darkest Side of Gardening

We all love bringing new flowers, trees and shrubs home from the garden center. These plants add color, texture or flavor to our landscape – sometimes all of the above. Unfortunately, they leave a less desirable legacy too – a pile of empty plastic nursery pots and trays. You might say this is the darkest side of gardening.

Most of us aren’t keen on adding this material to the landfill, so these piles of plastic stack up.  Options for recycling these items are few and far between, but there’s one organization that has been committed to recycling horticultural plastic for the past 20 years. Today, I revisit a conversation with Dr. Steven Cline, founder of the Missouri Botanical Garden’s plastic pot recycling program.

Dr. Steven Cline sorting through a large pile of plastic nursery pots at the Missouri Botanical Garden collection center.

Dr. Cline was manager of the William T. Kemper Center for Home Gardening at the time of this interview, and he spearheaded the innovative plastic pot recycling program through the Missouri Botanical Garden (MOBOT) in 1997. This program became the most extensive public garden recycling program in the United States, and it all started on whim based on his own experiences.

The Growing a Greener World crew and I filmed an episode of the recycling crew at work and shortly afterward, I asked Dr. Cline to join me for this in-depth conversation on the subject.

A Recycling Success Story

The Missouri Botanical Garden recycling program was born out of Dr. Cline’s frustration with the stacks of plastic pots accumulating in his garage – with no environmentally-friendly option for disposal. As he discussed the issue with his colleagues at MOBOT, the need for a grassroots recycling effort became more evident, and the plastic pot recycling program was born.

During its first year, the program collected 10,000 pounds of plastic pots and trays. Considering how light these individual items are, you can imagine the size of that grungy, plastic heap.

Dr. Cline talking with one of the many volunteers needed to sort and prepare the mounds of horticultural plastic.

Area gardeners were eager to contribute their stockpiles to the recycling efforts. So with this overwhelming response and ongoing support from area grants, the program continued to expand to the point of collecting over 160,000 pounds of horticultural plastics in 2008. That was all in just one year and from the gardeners in one American city.

Unfortunately, that’s a mere drop in the proverbial bucket of the 350 million pounds of trays and pots generated in America each year – enough to fill two baseball stadiums.

Program organizers soon realized that some area gardeners wanted to participate but weren’t able to make the drive to the MOBOT facility. So, satellite collection stations were established – providing large drop-off bins at garden centers throughout the St. Louis region. Gardeners were responsible for sorting their plastics at the drop-off point to keep plastic types separate, and garden centers committed to overseeing this effort.

In 2017, MOBOT teamed up with Central Paper Stock (CPS) as the official plastic pot recycling manager. CPS has been in the recycling business since 1946 and has invested in equipment to effectively process horticultural plastic. Their resources allowed the program to increase its capacity and the number of drop off sites around the city.

The Challenges of Recycling

So, why aren’t plastic pot recycling programs prevalent across the U.S. and Canada when there is clearly such a need? A horticultural recycling program is a tedious and complicated process.

There are three types of plastic commonly used for horticultural products:

• Polystyrene – This is the lightest of the three types and is difficult to mark with a recycle indicator. Polystyrene is most commonly used for trays and seedling cell packs.
• Polypropylene – This plastic is usually marked with the recycling indicator 5.
• Polyethylene – This plastic is usually marked with the recycling label 2.

The last two types are usually – but not always – marked with their recycling number. Recycling markers tend to be small and difficult to find on the bottom of the pots. Meanwhile, some older plastic pots are made of plastic which can’t be recycled. All these issues make sorting a challenge.

Recycling markers are typically difficult to find and are located on the bottom of the pot. The marker at left, here, is actually larger than many. The Southern Living pot, on the right, is a great example of marking with greater visibility for sorting.

Why is sorting important? Once sorted, the plastics are put through a grinder. The resulting chips are approximately 3/16” in size, and those chips are melted down to be made into other items. Yet, different plastics melt at different rates. If a container of plastic chips is a mix of types, those chips can’t be melted. They become tiny chunks of trash.

Adding to the complications of recycling, those plastic pots contain materials which can’t be included in the recycling process. As much remaining dirt residue as possible must be removed from each pot and tray. Many of these containers have metal hangers, metal rings, or metal clips – often used to hold a plant tag or other marketing material. This metal can’t be run through the grinder and must be removed – by hand, one pot at a time.

You can begin to understand just how labor-intensive and time-consuming the recycling of horticultural material is – not to mention the space needed just to collect the vast quantities of pots that are out there.

Oftentimes, there are metal rings, clips and hangers on nursery pots. The metal can’t be processed during recycling, so it must all be removed by hand.

Even when an organization is committed to proper sorting and preparation, they still have another issue to contend with. Demand. The value of the recycled plastic material is constantly rising and falling – based on issues such as petroleum prices and material exports.

During periods when the recycled plastic is at a low market value, it’s difficult or even impossible to keep a recycling program financially viable.

Exploring Other Options

As the love of gardening increases, the issue of leftover storage materials isn’t going away. There are, however, some industry leaders looking to make a difference.

Monrovia, for example, understands the importance of finding a better way and was instrumental in supporting the MOBOT recycling program. Many industry leaders recognize the need to standardize pot sizes or make the recycling symbol more visible – both steps which would make sorting easier.

There are some in the industry who have made strides in finding plastic alternatives. So while shopping for plants, look for containers made of organic (and compostable!) environmentally-friendly options; such as rice hulls, recycled paper and bamboo.

That said, plastics aren’t going away anytime soon. So, what to do?

Recycling efforts are a good step, but there are two better options to explore before recycling ever comes into play.

Once the sorted plastic is run through the grinder, the resulting chips are packaged to be melted down and made into new products.

Reduce or Reuse Before You Recycle

Reducing or reusing plastic pots are the two best steps that we, as gardeners, can take to keep these materials out of the landfill.

Reduce doesn’t mean avoid shopping for plants. It simply means looking for those eco-friendly options. They certainly aren’t as common, but look for them – and ask for them – where you shop for your plants. When you vote with your dollar by choosing those materials over plastic, the industry will take notice.

Another way of acquiring fewer plastic pots is to buy bare-root plants. There are many bare-root options available, primarily when you order online.

But the easiest and most practical way to keep plastic pots and trays out of the landfill is to reuse them. You will inevitably find yourself with a stack or two, but you may not realize what useful tools they can be for you all throughout the year.

Bare-root plants are kept in a state of dormancy, so they don’t require soil. Once you bring them home, you soak their roots and plant them in the ground, and when environmental conditions are right, the plants will break dormancy.

I received a flood of creative uses from the joe gardener Facebook group, when I asked my members how they were putting their pots to work in the garden. From those responses, I selected my top ten recommendations. You can check out that list with full descriptions and group member credits in a recent blog post.

Here is a quick recap:

1. Save your containers for those times you need to transplant, divide or pot up cuttings from specimens from your landscape.
2. Give them away to friends or organizations who would love to get their hands on them. Check with your local Master Gardener group, nature center, native plant organization, a school or community garden, or even a local nursery.
3. Use pots to hold pots and keep your landscape looking photoshoot ready by sinking an empty pot into your landscape beds. Throughout the year, you can drop new or seasonal-color plants into those empty pots to showcase blooms or foliage without having to take time to plant them in.
4. Capture strawberry runners by filling pots with soil and placing them under the runners. Press the runner into the soil, and once it has rooted, it can be cut free and replanted or given away.
5. Create a mini-worm compost system by drilling holes in the sides and bottom of a pot. Sink the pot in the ground of your garden and fill it with compostable materials. Worms enter and leave through the holes and break everything down into compost for your garden.
6. Use smaller pots as fillers for large containers. Set small or medium-sized pots upside down in the bottom of the larger container before filling it with soil and plants.
7. Use larger empty pots to move and distribute mulch and compost. Since they are lightweight and big enough (but not too big), they are perfect for this task.
8. Stash empty pots to use as weed buckets. Tuck the pots behind raised beds, shrubbery, etc. throughout your landscape. As you weed, prune or gather other garden debris; an empty pot will be close at hand to gather things up.
9. Build pest deterrents by cutting out the plastic pot bottom and placing the remaining collar over new or small seedlings to keep rabbits away.
10. Restrain aggressive spreaders that are best not planted in the ground. Sinking the plant – while still in a pot – into the ground keeps roots in check.

I love reusing smaller plastic pots to hold new cuttings. The smaller cell packs are also ideal for starting seeds.

So, those are my reuse recommendations and here’s one more as a bonus:  An empty pot is valuable to protect birds and beneficials in your garden. If you use baits or poison to control fire ants, place an empty pot over the treated mound until the treatment dissipates, so the friendly visitors to your garden aren’t exposed to those chemicals.

If you have another reuse for your plastic nursery pots, I would love to hear about them. I encourage you to share them in comments below.

It’s unfortunate that the containers of those plants we love so much can cause so many complications. This issue is as relevant today – and perhaps more so – as when I originally spoke with Dr. Cline. Change comes with knowledge. Now that you know the challenges of plastic recycling and the many benefits of reuse, I hope you’ll commit to putting these ideas to work for you.

I also hope you’ll listen to the podcast recording (if you haven’t already), to hear more on the program’s development and impact.

Links & Resources

joe gardener Blog: Top Ten Tips to Repurpose Plastic Pots

joegardener Facebook Group (Gardener community sharing experiences and success stories)

joe gardener Instagram (GardenFarm & behind-the-scenes photos along with helpful garden tips)

joe gardener Twitter (Behind-the-scenes updates and more garden tips)

GGW Episode 720: Talking Trash-Dealing with Plastic Pots, Packaging and more

GGW Blog: The Ugly Truth about Gardening

GGW Blog: Recycled Nursery Pots are a Hot Topic – Readers Respond

GGW Blog: Plastic Pot Recycling – One Silver Lining in an Otherwise Dismal Effort

GGW Blog: Why to Love Bare Root Trees and Shrubs; and How to Plant Them

Missouri Botanical Garden Plastic Pot Recycling Program

Central Paper Stock (CPS)

Milorganite® – Our podcast episode sponsor and Brand Partner of joegardener.com

About Joe Lamp’l

Joe Lamp’l is the creator and “joe” behind joe gardener®. His lifetime passion and devotion to all things horticulture has led him to a long-time career as one of the country’s most recognized and trusted personalities in organic gardening and sustainability. That is most evident in his role as host and creator of Growing a Greener World®, a national green-living lifestyle series on PBS currently in production of its ninth season. When he’s not working in his large, raised bed vegetable garden, he’s likely planting or digging something up, or spending time with his family on their organic farm, just north of Atlanta, GA.