Choosing containers for seed starting

Containers for seed starting are widely available at garden centers or through garden catalogs. There are enough choices that one can go dizzy trying to decide which container(s) to choose. Below you will find some options that I have used in the past and my recommendations for future use. 

Reusable containers

• Thin-walled plastic pots are the most economical containers on the market since they can be cleaned, disinfected, and reused year after year. Seeds may be sown and grown in plastic pots, but the plants must be removed from the pot before transplanting. Often, the plants become root bound and the roots must be carefully teased apart just prior to planting.

• Plug trays, constructed from either plastic or Styrofoam, are one-piece flats that are divided into individual cells. These are fantastic for starting seeds, but most seedlings will need to transplanted into larger pots (a process called potting up) once the first or second set of true leaves form. Plug trays are often sold as part of a seed starting kit. These kits are like mini-greenhouses that help to ensure success when starting seeds indoors. Most seed starting kits include the plug tray, a flat tray that is used as a water reservoir, a felt mat that uses capillary action to draw just the right amount of water from a reservoir into the soil, and a clear lid to hold in humidity during germination

• While clay and ceramic containers are another reusable option, I do not recommend these as they dry out too fast for starting seeds. 

Biodegradable containers
Biodegradable pots are a convenient alternative to reusable containers, as they do not need to be cleaned, disinfected, and stored year after year. In addition, these pots can be planted directly into the garden. Thus, seeds can be sown, grown, and transplanted without the plants being removed from the pots, which helps to reduce transplant shock for the plant. Throughout the course of the growing season, biodegradable pots break down and release nutrients that help to improve the soil. I like biodegradable pots because I can write the variety name on the side of the container with a permanent marker – no more mixed up ID tags!

• Peat pellets are compressed disks when dry, but when placed into water, swell to form a “container” filled with peat moss. The outer netting (or sock) of the pellets readily disintegrates once planted in the garden. Peat pellets are real time-savers as all I have to do is get them wet, plant the seed, and wait. The pellets are really cheap and do not take up a lot of storage space. I love peat pellets for small seedlings that I transplant early such as lettuce and cabbage. However, it is difficult to label the variety without the use of plant markers (which do not really fit well into the expanded pellet).

• Fiber pots are eco-friendly and biodegradable pots that are made from wood fiber and peat moss. I have found that these pots tend to get moldy if there is not sufficient air circulation around the containers. Additional, I discovered that fiber pots do not disintegrate quickly and often result in plants with a stunted root system. If you decide to use fiber pots, I highly recommend slicing open the sides and bottom of the pots before planting in the garden so that the roots can penetrate the soil easier.  

• Cow Pots are eco-friendly, biodegradable, nutrient rich pots that are made from fully composted cow manure. These pots are odor-free and are an excellent choice for preventing root shock as they too can be planted directly into the ground. Seedlings seem to love this material as they grow quickly! Unfortunately, I have never actually planted these pots in the garden as I have had to pot-up before it is time to transplant outside. Maybe this year I will give these a whirl again.

• Coir pots are made from the outer husk of coconuts, a renewable resource, and consist of both coir dust and fiber. These biodegradable pots are great for transplanting directly into the garden as the roots easily penetrate the pots. At the end of the growing season, these pots may not be fully disintegrated but the plant’s root system will be long and deep which means the plants were growing happily.  

• Paper may also be used to start seeds. Repurposing newspaper to make small seed starting pots is a crafty way to minimize transplant shock. However, I have never used newspaper pots. Mainly because I no longer have a plentiful supply of newspaper waiting to be recycled. I am not sure how long newspaper pots will last prior to being transplanted into the garden.  In my opinion, it is more of a hassle to make the pots than it is worth.  Nonetheless, this may be something I try once or twice, just to say I did it.

Reusable and biodegradable containers offer the home gardener a wide variety of options for starting seeds and growing transplants. Container types include plastic pots and trays, peat pellets, and fiber pots of a variety of shapes and sizes. But do not forget, you can also reuse materials that you may already have in the house such as yogurt cups, Styrofoam cups, and cardboard milk cartons. 

Whatever you choose, select a container appropriate for the seedling size you want to produce. The container should have a few key characteristics to help get seedlings off to a good start. Containers should be at least 2” deep, clean, sturdy, and have 3-6 holes in the bottom to allow proper drainage. The containers should sit in a rimmed shallow tray or pan (with no holes) to prevent a mess on the floor when the excess water drains away.  

After a couple years with the trial-and-error approach for testing out different containers, for the second year in a row, I have decided to start all my seedlings in the APS-24 or APS-40 self-watering propagation system from Gardener's Supply, then pot-up the seedlings to plastic pots such as those from Greenhouse Megastore before transplanting the plants into the garden. 

* To disinfect reusable containers, use 1 part bleach to 9 parts water. Allow the container to soak for about 5 minutes then rinse with clean water.