Growing most plants from seed is easy as long as you provide the basics that all plants require—soil, heat, light, and water—and then avoid a few common pitfalls.
1. Begin by purchasing a commercial seed-starting medium or mixing your own blend. Whichever you way you decide to go, you need the medium to be sterile and fast-draining. I often use a good-quality potting soil (as opposed to a seed-starting mix) that I lighten by adding perlite to improve the drainage. I avoid using seed-starting media that is primarily made of peat, especially those tablet-like peat plugs. Peat has a weird relationship with water—it repels it and repels it, then it sucks it up like crazy and won’t let go of it. Either way, that’s no way to treat tender roots of new seedlings.
2. Fill small, clean containers with the soil mix, slightly moistened. (If using recycled containers, wash them first in a solution of nine parts water to one part chlorine bleach, allowing them to soak for a minimum of 10 minutes.) Plant seeds at the depth advised on the seed packet (usually the same depth as the size of the seed). With very small seeds, sprinkle them over the top of the soil and then press down on the soil surface to make sure the seeds have made good contact with the soil.
3. Water the containers thoroughly, preferably by setting the containers in trays of water and allowing them to absorb the water from the bottom up. Once the soil is completely moist, you can empty the trays of excess water.
4. Until seeds have germinated they need heat more than they need light. Heat pads made especially for seed starting can warm the soil to speed germination, but even placing the seed trays on a sun-warmed windowsill will help.
5. Check the seed containers daily and keep them evenly moist but not overly wet. Once the seeds germinate and the first leaves emerge, move the seed trays to a place where they will get direct sunlight or light from a UV-light bulb.
6. Once seedlings develop their first set of true leaves, they’ll be able to utilize more nutrients and you can begin feeding with small amounts of a timed-release fertilizer. Keep seedlings indoors or in a protected and covered place until outdoor daytime temperatures are above 50 degrees. At that time you can begin moving the seedlings outside for a few hours each day to begin acclimating them to the outdoors, a process called hardening off.
Damping off disease, which causes tender seedlings to wilt, discolor, and ultimately die, is not one disease but a general term applied to the affliction of any of a number of fungal diseases, including Botrytis, Fusarium, and Phytophthora, that affect seeds and seedlings. There’s no cure for damping off, so prevention is the best course of action and the best way to prevent it is to keep your seed-growing environment as sterile as possible.
Legginess is a condition that can afflict seedlings when they get insufficient light. In an effort to reach more light, the plants develop tall, spindly stems. Legginess won’t kill a plant but it can lead to a weak structure that may more easily break or bend. To avoid legginess, move your seedlings to the best available light source and harden them off as soon as outdoor temperatures will allow. Using a fan to blow to a gentle breeze over the seedlings can also help to strengthen the stems.