Tend the Crop
Seeds take anywhere from a few days to a few weeks to germinate. During this period, it is important to keep the soil damp but not soggy. You’ll want to water gently—try a spray bottle or a fine-sprinkling nozzle on a watering can to avoid disturbing the seeds. Make sure the flats are well drained to avoid rotting the seeds or encouraging disease. Check daily to be sure water isn’t standing in the bottom.
When green leaves emerge from the soil, your seeds have germinated: bottom heat is no longer necessary, but light is essential. The lights should always be 1 to 3 inches above the tips of the leaves as they grow, and they should be on for 12 to 14 hours per day. Watch your seedlings closely to make sure they are neither leaning sideways toward the light nor touching the bulbs. Once the seedlings have developed their first set of “true” leaves (a second set of leaves after the cotyledon leaf set—see detail in above diagram), begin fertilizing once a week with a half-strength organic liquid fertilizer.
At some point, your vegetables will outgrow their flats or pots. If temperatures outside have not yet reached the level that the plants need to thrive, you will have to transplant them to a bigger pot. The process is easy but requires a little dexterity: use a fork, chopsticks, or another slender tool to extract each seedling’s roots from the soil without disturbing the fragile stem. Fill the new pot with fresh potting soil and make a hole the size of the root system. Gently transfer the seedling into its new home and delicately tamp fresh soil around it so its roots are firmly planted.