Chances are you've seen the tiny pressed pods of compressed soil known as "peat pots" at the local nursery before. Many people like to get their seeds started indoors, and a great way to do so is by using biodegradable containers like peat pots. To make sure plants get the best possible start, you'll also need to work a slow-release plant food into your potting soil. Here's how to get started:
Picking the Right Container
Choose a biodegradable container that works for you. Most are made from compressed earth or fine mesh. In either case, you’ll want to put them in a plastic tray of some kind to prevent too much water from seeping through them. Some biodegradable containers are even placed inside "mini greenhouses," whose dark plastic bases and clear plastic roofs both trap and circulate excess water. These containers can be especially good if your home is not particularly warm and you want your plants to be able to retain all the sunlight they get during the day. You don't need to worry about the mini-greenhouse not being biodegradable, either, because a single one will probably last you several growing seasons.
Prepping the Containers for Planting
Hydrate the peat pots with warm water − warm, but not hot. Be sure to follow the instructions from your nursery about how to hydrate the medium you happen to be working with. Give the pots enough time to truly decompress and become light and fluffy. It isn't necessary to hydrate pressed-earth pots, but you will want to water the seeds inside of them after planting. Add a few granules of a slow-release plant food like Osmocote to each container. Slow-release fertilizers give plants a consistent source of the nutrients they need over longer periods of time. Providing nutrition as your pots hydrate will only give your seeds better chance of thriving.
Plant one or two seeds per container and label each row accordingly. After all, it’s very easy to forget what plant is what until they are actually growing, so this step is especially important. Planting any more than two seeds per pot can easily lead to overcrowding. It's better to just grow that third plant later on than it is to risk letting it choke out your other two seedlings.
Depending on where you live, you may have to continue monitoring and watering your seeds for up to eight weeks. In most areas, three or four weeks should be fine. Try your best to plant hardier varieties about two weeks before the last frost of the winter, and wait until that frost passes to start those summer varieties that can't take hard freezes. During this time, you may see some seeds shoot up and others remain rather tiny. To encourage growth, add one or two more granules of Osmocote to each container, which will take months to fully release but begin working almost immediately.
Planting Your Biodegradable Containers Outdoors
When the weather is right, you'll want to find a good spot for your seedlings in your yard or garden. If you've been growing out of peat pots until now, try your best remove the mesh from each container without damaging any root systems. Many plants will remain entangled in that mesh for far too long a time — even if it does eventually biodegrade. Be extra careful when transplanting pressed-earth pots. Weeks of watering usually weakens the integrity of these containers, making it quite easy for them to fall apart. This is also a good thing, though, since it means you just can dig a hole big enough for the pot, place it in the ground, and fill in dirt where needed. The pots will fully disintegrate into the soil within a few weeks, leaving the roots completely free to grow.
Make it a point to take note of your container's rate of decay. Many products billed as “biodegradable” may indeed decompose over time, but only after a lot of time has passed. As you check on the containers, you should also note which plants need a bit of a pick-me-up. Gently mix some more plant food into the top layer of soil around these plants, being careful not to disturb their roots as you do so. The transplantation process is eased by the use of biodegradable containers, but it is still a bit of a shock for plants to be exposed to a new level of sunlight, temperature, and soil conditions. Slow-release plant food helps make sure that the necessary nutrients are there when the plants do get accustomed to the new environment.
When you're looking for an easy way to transplant your indoor seedlings, especially in zones where the last frost comes rather late in the spring, biodegradable containers are the way to go. When paired with Osmocote for slow-release nutrition, these pots can help your plants reach their full potentials and extend your growing season by quite a bit.