A biodegradable pot to start seedlings in that can be planted right into our gardens sounds like the perfect plan, and many gardeners use them reliably year after year. However, peat pots can be tricky and aren't the cure-all we hoped they would be.

Not all biodegradable pots are peat pots, although all peat pots are biodegradable. Kind of like not all rectangles are squares, but all squares are rectangles. Biodegradable pots can be made from manure, wool, peat, coir, and other materials, and are often a blend of several. There are also pellets of peat or other natural materials, which don't require any seed starting mix–the seed is dropped inside, and water swells the material around the seed. For this article, we're talking about peat pots–the compressed and fibrous light brown pots meant to be filled with seed-starting soil and used to start seedlings.

The Good

Peat pots eventually become biodegradable, and some are even organic, listed with OMRI (the Organic Materials Review Institute). Many peat pots are no longer pure peat and contain wool or other materials to help with the issues discussed below. Since they are single-use containers, sterilizing them before reusing them the next year isn't an issue.  

Using peat pots instead of plastic eliminates the problem of typically unrecyclable plastics in our garden efforts. Old or used peat pots can be tossed into our compost piles or shredded by hand and used as mulch in the garden.

Plants that typically don't transplant well may be candidates for peat pots. If used carefully, they can minimize soil disturbance around the roots. Many cucurbits, such as squashes, melons, pumpkins, and cucumbers, dislike being transplanted, and a properly sized peat pot can help. While those plants are typically directly sown in the garden, pest issues (squirrels and chipmunks, anyone?) can necessitate starting them indoors. 

Tips for successfully using peat pots

If you'd like to use peat pots for seed starting, here are a few best practices:

1. Watch the moisture levels closely. Peat pots should not be allowed to sit in water on a tray. Unlike a cell pack of plastic pots, which is watered from the bottom, peat pots should be watered from the top. 
2. Space the peat pots out to allow airflow. Any biodegradable material kept constantly wet is a target for molds, but good airflow can reduce the issue. Peat pots kept tightly packed together are more likely to have problems.
3. If your peat pots are still quite tough at planting time, you'll likely need to cut them to help them break down and allow roots to escape into the soil. Use a scissors or sharp utility knife to make several cuts down the pot and around the bottom. The roots will find the holes and work their way out. Don't just rip the pot off and damage all the fine roots.
4. When transplanting seedlings grown in peat pots, cut away any portion of the top edge of the pot which sticks above the ground. Like a lantern wick, the pot edge above ground will draw moisture up from around the plant and release it into the air. 

The Bad

Peat pots have a reputation, and it isn’t a good one. Many gardeners have moved away from them for the reasons below.

They often don't break down quickly

The big idea with peat pots is to plant them directly in the ground, and they'll decompose and turn into soil—no disturbed roots, no muss, no fuss. Unfortunately, it doesn't often work out that way. Peat pots will decompose in the soil, but on a scale that is too long for our plants. Many gardeners including myself have dug up almost fully intact peat pots at the end of the year.

Often, they constrict the plant's roots and limit growth. Gardeners who do use peat pots will cut or tear them, remove the bottoms, or just pull them off to solve this problem. However,that negates the supposed advantage of using them in the first place, which is minimizing root disturbance. Seedling roots often grow into the peat material, making removal difficult without damaging the roots. 

A recurring expense

While peat pots are not used-car expensive, they do need to be purchased every year. Unlike reusable wood or plastic pots, peat pots are single-use items. They're even more expensive on a per-plant basis when purchased in small retail quantities most gardeners need. If you want to purchase peat pots, buy enough for several years to get them at a better price.

It's still peat; is that a problem?

Peat is a naturally occurring material that can be harvested ethically and responsibly or not, depending on regulations and the source. Much peat available in the United States comes from Canada, where legislation and oversight protect peatlands from over harvest. Similar to sustainably managed forest products, the Canadian Sphagnum Peat Moss Association (CSPMA) inspects peat harvesting operations and ensures compliance with best practices for sustainability. 

But peat harvest still disturbs a fragile ecosystem, and to some, that is not acceptable. Like plastic containers, peat has an environmental cost. Look for products with the CSPMA logo to ensure the peat is being harvested correctly and the bogs are treated responsibly.

The Ugly

Peat pots are often purchased by gardeners to start a few dozen seeds, and they can cause big problems. Peat holds moisture well, which is why it is used as a component in potting soil mixes. The issue is how long it retains moisture. Peat pots often stay wet, soaking up moisture from the seed-starting mix but not giving it back. The seedlings look like they need to be watered, so we provide more water. The peat pot stays wet. Soon, mold sets in. 

Mold on the peat pots can cause issues for us and our health, but also for our seedlings. Overwatering leading to wet, moldy conditions is likely the leading cause of dead seedlings. Damping off, caused by several water molds and fungi, kills thousands (millions?) of garden seedlings every year. 

When planted in the soil, more problems arise. While peat pots will degrade, it usually doesn't happen nearly fast enough, and the small peat pot ends up acting like a plastic container in the ground, minimizing root growth and effectively choking the plant. Look on gardening forums and you'll find many stories of sad gardeners who lost an entire batch of seedlings to either mold issues or slow decomposition of the pots once in the garden. 

Alternatives to Peat Pots

While peat pots seem like a great idea, they can be challenging. So what is an environmentally concerned gardener to do? Here are a few other ideas that are better for your seedlings.

Wood Seed Starting Trays

If going old school appeals to you, look into wood seed starting trays. Before plastic trays, gardeners and growers started seeds in wood trays. Properly sealed and cared for, they can last years. Plus, you can make them at home. Be sure they have drainage holes.

Reuse plastic seed starting trays

Plastic seed-starting trays are the professional growers' choice for a reason: they're effective. However, they are plastic, and that gives some people pause. When treated carefully, they can be reused for years. I have seed-starting trays I've used for over five years, and they are still going strong. Sanitize them between uses with a 10% bleach solution. I fill a tub and just let them soak while I go do something else. Rinse and reuse.

Peat Pellets

Unlike peat pots, peat pellets don't have a wall that restricts roots. They are basically a package of lightly compressed peat and sometimes potting soil held together by a mesh, with a hole in the center. Hydrate the pellets (warm water works much faster), and plant the seed. The pellet absorbs water and swells up tight around the seed, and the mesh holds it together.