Starting vegetable and flower seeds indoors is easy if these steps are followed.
The first step is seed selection. Make sure they are high-quality (purchased from a reputable seed dealer) and free from weed seeds. Hybrid seeds generally cost more than non-hybrid cultivars but may have increased vigor, better uniformity, larger yields, resistance to some diseases and other desirable qualities. If seeds from previous years are used, the germination percentage decreases. How much depends on how they were stored. If stored in a cool, dry location, many seeds will germinate to acceptable percentages for a couple years.
Sow seeds in any container, as long as it has proper drainage and does not contain toxic substances. Previously used containers need to be cleaned thoroughly with a disinfectant or soapy water. Use seed-starting kits or fill plastic, clay or peat containers with growing media. Desirable media is loose, fine in texture and drains well. Purchase commercial container/starter mixes or buy materials and mix yourself.
Sow seeds according to package directions; some may need to be covered with a thin layer of soil. The use of plastic over the top of the planting container retains moisture and humidity needed for germination. Keep seeds out of direct sunlight until they germinate. Days to germination varies with plant species. Time seeding of warm-season transplants to synchronize with when seedlings can be moved outdoors following the last frost.
After seeds emerge, remove plastic cover and place near a bright window or under energy efficient grow lights. Keep the light as low to the seedlings as possible, to prevent stretching. Seedlings in soilless mixes need regular fertilization. Apply a water-soluble fertilizer at half-strength a week after seedlings germinate. Then fertilize every two weeks at full strength.
Transplant seedlings after they develop at least one set of true leaves (the leaves above the cotyledons or “seed leaves”). Transplant into individual pots or thin within the flat. Remove seedlings carefully to preserve as many roots as possible. Seedlings are fragile so avoid picking them up by the stem.
Approximately two weeks before planting outdoors, begin hardening off the fragile seedlings to increase their chance of survival. Place them outdoors where they will receive direct gradual sunlight. Start with a couple of hours of sun, then gradually increase and expose to some wind for a few hours each day for a week. Gradually lengthen the amount of time outside each day. Move the plants inside at night if temperatures drop to near freezing. Keep them watered and once the plants are hardened, transplant into the garden and enjoy the summer’s bounty!
Starting seeds indoors is a simple and inexpensive way to enjoy many plant varieties not commonly found in garden centers. Seeds can be started in containers found around the household – plastic trays or cups, egg cartons, and the like – or in seed starting trays or peat pots from the garden center. Regardless of what container is used be sure it has holes for drainage.
A commercially available seed starting mix or fine textured potting mix will provide a sterile, weed-free medium in which to start the seeds. Plant seeds according to package directions. It is generally recommended that most seeds be started four to eight weeks prior to the last killing frost.
After planting the seeds, water them in with a fine mist hand sprayer and cover lightly with a layer of plastic. Until the seeds germinate, keep them in a warm location away from bright sunlight. Most seeds prefer temperatures between 70-75°F to germinate. Seeds in the Solanaceae or nightshade family germinate better if soil temperatures are close to 80°F. As the seedlings emerge, remove the plastic and move the container closer to a bright window or light.
For proper growth, seedlings require adequate light. If a bright window location is unavailable, suspend a fluorescent light fixture three to four inches above the new plants. A combination of one cool white fluorescent tube and one warm white tube will provide the broad spectrum of light needed. For best growth, keep the lights on 12 to 16 hours daily.
After seedlings grow and develop true leaves, fertilize with a quarter-to half-strength water-soluble fertilizer to stimulate healthy, even growth. As soon as the seedlings are large enough to handle, carefully transplant seedlings into their own small pots to provide them room to grow.
Take care not to expose seeds and seedlings to cold drafts or allow them to wilt. Watch for signs of disease. Too much moisture, high temperatures, and poor light weaken the plants and make them susceptible to the damping off fungus.
About two weeks before transplanting into the garden, start the hardening off process.