Seeds started in winter or early spring are usually started indoors in cell packs or flats 6-8 weeks before the last frost. The keys to successfully starting seeds are: 1) using a soil-less seed starting mix in clean cell packs or flats, 2) maintaining temperatures between 60-80°F., 3) keeping the humidity high, and 4) providing a strong source of light (not direct sun).
We start the vast majority of our seedlings in flats filled with Supersoil brand mix. Then we cover the flats with clear plastic humidity domes and place them under (as close as possible) 4 foot pairs of fluorescent lights. If you do not have access to humidity domes, the next best coverings are saran wrap or a pane of glass. It is necessary however, to turn these covers over daily to avoid an excessive buildup of condensation. As for the lighting, we alternate warm and soft fluorescent tubes and this gives our seedlings the entire spectrum of light they need to thrive.
Once seedlings are up remove the humidity dome within a couple of days. The best way to water new seedlings is with a small pump mister bottle. When they have two sets of true leaves they are ready to be transplanted into the garden or larger containers. It is important not to leave the seedlings in the flats too long or they will become spindly and root bound.
Seedlings require a “hardening off” period when they are gradually exposed to the stronger light and cooler temperatures of the outdoors. We keep our seedlings in light shade, under an overhang for a few days before transplanting them into the garden.
With practice you will develop your own seed starting style and will likely be surprised at the very wide range of plants that can be started economically from seeds. Remember, the keys are sterile soil and clean cell packs or flats, warm temperatures, high humidity and strong light. Get growing!
This proven method for starting seeds indoors is easy to adapt to outdoor sowing during frost-free months: Place flats or pots in light shade outdoors, keep out of direct sun until germination occurs. Humidity domes are not used in sunlight, remove domes once seedlings sprout.
A water resistant table, placed under an overhang or awning is a highly effective, inexpensive method for starting seeds outdoors.