Selecting Biodegradable Seed Starting Pots
The first thing you'll notice when buying biodegradable seed starters is that you have three options: There are square pots, round pots and trays of strips. The individual round pots and square pots generally come in two sizes--small and large-- while the strips I've only found in one.
If you read any available packing for the seed starting pots you'll notice that they are generally made from three things. They can be made from peat, coconut coir, "recycled materials" and dried cow manure. The pots made from cow manure aren't as easily available, but you should ask for them at your garden center if you are interested in lessening the dependence on plastic in your seed starting operation.
Peat, Paper or Coir Pots: Which are Sustainable?
Peat Seed StartersOver the past two years I've been involved in conversations with other gardeners about the use of peat. These conversations usually boil down to someone in the industry trying to convince me, or people around me, that harvesting peat can be done in an environmentally-friendly manner. I do not subscribe to this idea. Personally, I don't want to contribute to the destruction of an ecosystem while trying to develop one in my own yard. If I'm giving peat pots I'll use them. But I don't go out of my way to buy them. You should read the peat page and educate yourself on the pros and cons of harvesting peat and make your own decision.
Coir Seed StartersSeed starter pots made from coconut coir, a waste product, is a great substitute for pots made from peat. I like coir so much that I use it as my seed starting soil too. Recently, I've had gardeners express concern about the salt levels in this medium. I've never encountered a problem with it, and I wonder if it isn't one that has been pushed by the peat industrial complex.
Paper Seed StartersFinally, over the past three years I've noticed these pots made from "recycled materials" are becoming more and more available in dollar stores and big box retailers that devote a small section to seeds and seed starting supplies in the spring. I've yet to call the company to ask what exactly "recycled materials" they use, but given their low price, density, and how the pots react to water-- I'm pretty confident that it the product is recycled paper.
Starting Seeds in Biodegradable Pots
The first thing I do when starting pots these pots made from natural fibers is to check if there is a drainage hole. In the case of the strips, I've noticed that the drainage hole's size can vary from strip to strip, and from one cell to another. If you look at the picture above, you'll see the irregular drainage holes in each of the pots that come in strips. These holes are rather large and a lot of your seed starting mix will fall out if you lift the pots and when you water. I like to take a small piece of napkins and just cover some of the hole to minimize the loss of my seed starting soil.
In the image above, the pot made from "recycled materials" is the only one with a precisely cut drainage hole. It's another indication that makes me think it is made from paper as the cut is too clean for it to be peat or coir.
Before filling these pots with your seed starting soil I recommend you moisten the pots with either a spray bottle, or by dunking them in warm water for a few seconds. Not too wet, but make sure they are moist. I even go so far as to moisten my seed starting mix before adding it to the moistened biodegradable pots. Pots made from natural fibers will wick away moisture in your seed starting mix and from planted seeds resulting in poor germination rates. This goes for newspaper pots and pots from toilet paper rolls, too! Keep it an eye out for pots drying out when temperatures get warm and on sunny days if you're starting seeds in your windowsill. They dry out real fast.
How to Plant Biodegradable Seed Starting Pots
After all danger of frost has passed, it's time to take your seedlings that you've grown and tended to indoors and introduce them to your garden beds or container garden. Dig a hole or trench that is wide enough and deep enough to set your biodegradable pots in. The depth is very important. If any portion of the pot is exposed above the soil line, the air circulating above ground will wick away moisture from the pot. Then the pot will wick away moisture from the surrounding soil and you'll be left with dead seedlings. This also applies to the paper tube and newspaper pots.
Herbs planted in biodegradable seed starting pots.
Pepper plant planted in biodegradable seed starting pots.
When you buy plants that have been commercially grown it is often recommended that you gently break apart the soil and roots to promote root growth, and counter the effects of the plants having become root bound. It's a good idea to break or tear apart these pots when you are planting them in ground and in containers too. The second to last photograph shows an herb I planted in a pot and you can see that the roots grew through the pot. In the last picture the roots of a pepper plant didn't grow as vigorously through the pot and would have benefited from the pot having been broken to allow them to penetrate the surrounding soil as the roots concentrated on growing around the surface of the pot.
Planting biodegradable seed starting pots in the garden, while better for the environment, require a bit of planning and thought. Don't allow them to dry out completely when you're starting seeds in them. Especially the seedling pots made from paper. They can be harder to initially water and will hold more water than the pots made from peat and coconut coir, but they are more durable.
After transplanting your seedlings into the garden ensure that the pot is completely covered in soil to prevent the air from drying out your plant and seedlings. These natural parts will break apart and decompose on their own, but it is a good idea to help the seedlings, and the decomposition process, along by breaking the pots when you're planting them in the ground.
More Seed Starting Tips
Eco-Seed Starter from Burpee
Seed Starting Bio-Dome from Plastic Bin
Seed Starting Tips for Beginner Gardeners
You can also look over the archive of my posts about starting and saving seeds from your garden for more tips, suggestions and recycling ideas for seed starters all in one easy to remember page.