Instead of buying pepper, eggplant and tomato plants, I enjoy growing my own transplants, varieties that may not be available in local garden departments. Not all transplants pass the taste test, or the Alabama summer humidity test and it may not be a money saver if you only grow a few plants each year. It is also a good bit of work, but with a little preparation, you can produce quality vegetable transplants indoors if you are not lucky enough to have a greenhouse.
Pick a planter
After obtaining your seeds, it’s time to pick a container. If you want to start a large number of seedlings in a limited work area, wooden flats and plastic trays are recommended because they take up less space than individual pots. When using these types of trays, seeds are not planted into individual cells so they will need to be divided later and potted into separate pots. Seed trays, typically black plastic trays with cell inserts, are available at garden stores as well although containers can often be found around the house. Yogurt containers, disposable cups, fast food salad containers, egg cartons — there are lots of choices. Just make sure the container has drainage holes so excess water can run off.
Get the seedlings off to a good start by filling containers with a sterile potting mix. Garden soils are not sterile and should not be used as a potting media. The easiest option is a pre-mixed potting mix composed of vermiculite and peat moss. These are suited for long-term transplant production (4-10 weeks) and generally can provide nutrition to the developing seedling for up to two weeks. Note this is not potting soil, but a potting mix. If you prefer, you can mix up your own potting with peat moss and vermiculite.
Potting mixes are hard to water when they are completely dry so before filling containers, wet the mix so that a bit of water drips out when you squeeze it in your fist. This is easier to do in a large container like a 5-gallon bucket. Water will likely run out the bottom of the container if you try to wet the mix after it is in the container.
After filling containers, make a small indention in the top of the mix with a pencil or other implement. Seeds should be planted about two to three times their width. Cover with mix and tamp down gently — a bit of seed-to-soil contact speeds up germination. Seed-starting kits come with a clear dome lid that holds in moisture and creates a humid environment for germination, but you can do the same thing by covering the flats with plastic wrap and keeping them covered until seeds have germinated.
The growing area must be warm. Generally, the temperature should be between 60-65 degrees at night and 70-75 degrees during the day. Heating mats to keep soils warm while the seeds are germinated are available. Keep seedlings away from cold windows or drafts from air vents; the top of the refrigerator is a good place to keep them.
Once seedlings have germinated, remove the wrap or plastic dome and subject the seedlings to light. Warm, sunny windows are often not enough for young plants and they become very tall and spindly. A south-facing sunroom makes a great location for seedlings, but fluorescent lights can also be used. A fixture containing two 40-watt, cool-white fluorescent or grow-light tubes spaced 3-4 inches apart is sufficient. Place seedlings about 2-3 inches from the tubes, and leave the light on for 16 to 18 hours each day. Raise the lights as plants grow to prevent leaf burn. Keep an eye on the media as it will dry out quickly, and water as necessary without letting the soil dry out. About two week after seedlings emerge, the plants will need fertilizer. Water-soluble fertilizers work well. Dilute the fertilizer to one-quarter or one-half of the recommended amount and apply once a week.
Don’t forget to harden the transplants off before planting them in your garden. Over a two-week period, set plants outside in partial shade to receive lower temperatures during the day, and bring them back in at night. Each day increase the amount of time plants are outside and subjected to full sun. In case of frost or cold weather, be sure to bring the transplants indoors.
Gardens may be full of cool-season vegetables now, but it will be tomato season before you know it.