I’m almost embarrassed to admit it, but peat pots only recently came into my life. I’d been gardening for several years before I even knew that peat pots existed. When peat pots finally did come to my attention, I jumped on the opportunity to use a more sustainable growing medium in my garden.
The short answer is yes, peat pots do decompose with time. The biodegradable materials that comprise peat pots will eventually break down, but even then peat pots can still cause problems for your seedlings, by inhibiting root growth and prolonging transplant shock.
Peat pots carry a bold promise, but between other gardeners’ assessments and my own experience, peat pots have mixed reviews at best. In this article, we’ll weigh the positives and negatives of starting seedlings in peat pots.
What are peat pots?
Peat pots are a common alternative to plastic seed-starting trays. The most well-known supplier of peat pots is Jiffy, and peat pots were first marketed in the 1950s as a sustainable alternative to plastic.¹
Designed to mimic seed trays and pots as closely as possible, peat seed-starting equipment comes in three main types. Peat strips are inserts that have been molded to resemble the cells in plastic seed trays. The most common size is two rows of six. Five inserts fit into a standard bottom tray, creating the equivalent of a 50-cell standard seed tray.
Peat pellets are dehydrated disks of peat contained by a biodegradable mesh. All you need to do is add water and the pellets rehydrate into a pot pre-filled with peat–complete with a small indention for seed-sowing.
Finally, there are peat pots–which are cardboard-like pots that come in various sizes, the most popular sizes being two- and four-inch pots. Peat pots may be square or round, and generally have drainage hotels in the bottom.
While the remainder of this article references peat pots, consider this to be a general discussion on these other two types of peat-based seed-starting equipment as well.
Are peat pots bad for the environment?
As the name suggests, peat pots are typically made of Spaghnam peat moss. In another article, I discuss the environmental implications of using peat moss in horticultural production, available here.
In short, peat moss is mined from primarily Canadian bogs at a rate that just isn’t sustainable. So while no one argues that plastic is better for the environment, peat pots aren’t exactly the guilt-free resource that so many companies claim they are.
However, there are some peat pots available that aren’t actually made from peat itself, but from coco coir and composted cow manure. Coco coir is a great substitute for peat moss, and as horticultural coco coir is the upcycling of a waste product within the coconut industry, I’d argue it’s a more eco-friendly option than regular peat.
Pros of peat pots
There are several reasons many gardeners advocate for peat pots.
As previously mentioned, peat pots do decompose, usually within a growing season. Rather than throw away peat pots, you can use old and broken pots to mulch your garden. Peat pots do double duty this way – they hold your seedlings as they start growing, and later they improve the quality of the soil where the seedlings are planted.
One quality of peat moss that gardeners love is its ability to retain moisture. Peat pots are no different–they hold moisture at a time when consistent moisture is crucial to seedling development. Peat moss is known to hold several times its own weight in water and slowly releases moisture as plants need hydration.
Reduce transplant shock
The idea behind peat pots stems from the problem of transplant shock. Some plants, even if properly hardened off and all care is taken to minimize transplant stress, will still suffer from the shock of having their roots disturbed.
Peat pots are supposed to minimize, and even eliminate, transplant shock. The idea here is that by burying the plant in its biodegradable pot, seedlings’ roots need never be disturbed–like they are when seedlings are popped out of plastic pots prior to planting.
Cons of peat pots
On the flip side, there are some negatives to using peat pots to start seeds and cultivate seedlings.
Peat is a nonrenewable resource
As previously mentioned, peat moss isn’t really a sustainable resource–eventually, we will run out of our global supply, and gardeners will have to find another growing medium.
Peat pots sometimes break down too quickly or too slowly
Yes, peat pots break down–but at differing stages, depending on how often they are watered, how much direct sun the pots receive, and the size and strength of seedlings’ taproots.
No one can promise you that your peat pots will break down exactly when you need them to–say, the day your seedlings get transplanted. Peat pots may or may not decompose within the first few days or weeks of planting, and could potentially cause your seedlings to struggle to bust through the pots with their young taproots.
For best results, break the peat pots apart with your hands before you plant them in the soil, much like you would loosen the plugs on rootbound seedlings.
Peat pots can get moldy
Because of their innate ability to retain moisture, peat pots are common culprits for green and white mold. To prevent your peat pots from growing mold (and decomposing faster) allow the soil to dry out between waterings. You might also want to incorporate a fan into your seed-starting room to better circulate air.
For more information about troubleshooting green mold on seedling trays, read this article.
Peat pots aren’t reusable
Peat pots, by design, are single-use. You can sometimes reuse peat pots and strips if you water sparingly, but eventually, peat pots will decompose, potentially making a mess in your seed-starting room.
Because of their composition, peat pots are more likely to harbor bad bacteria and fungal diseases that cause seedling damping-off. You can easily sanitize plastic seed trays, but it isn’t that simple with peat pots.
Make your own peat pots
If you’re concerned about using plastic, but you don’t want to buy new peat pots, you can make your own biodegradable pots at home. You can easily make paper pots out of:
- Toilet paper rolls
- Paper towel rolls
- Egg cartons
Making biodegradable pots out of toilet paper rolls and paper towel rolls is easy – just take scissors and cut into the roll four times, spaced evenly around the rim. Then, fold the newly-created flaps in on themselves just as you would close a cardboard box.
To make a newspaper pot, wrap several pieces of moist newspaper around a jar or bottle to create a mold. Fold and crimp the newspaper on one end to form a bottom. Allow to dry, and your newspaper pot is ready for seeds!
Egg cartons are simple – just cut off the lid of the carton and fill the bottom half with seed starting mix. It goes without saying, but be sure to use a cardboard carton, as styrofoam egg cartons won’t decompose.
Just be aware that all of these homemade paper pots will likely break down faster than peat pots. Newspaper pots and toilet paper rolls, especially, need to be contained in a box or a tray or they will lose their shape before the seeds are ready to transplant.
Some gardeners have great success with peat pots, while others have sworn them off entirely because of one bad experience. Why not give peat pots a try, and use the tips presented in this article to guide your techniques and troubleshoot any problems that may arise.
¹ “Our Brands.” Green Garden Products, https://www.greengarden.com/our-brands.