Apply your favorite liquid fertilizer every two weeks, following label directions. Be careful not to overdo. In much of the country, late winter and early spring are synonymous with seed starting, so here are some tips to help ensure that your seedlings get off to a healthy start. Group your seeds according to how long they need to grow indoors before transplanting to the garden. For example, tomatoes and eggplants generally need about 8 weeks of indoor growing, depending on the variety.
Squash needs only about three weeks.
It's convenient to grow plants that are on the same schedule in the same flats. Next, divide seeds into groups according to their preferred temperature for germination. This way you can avoid the frustration of sowing one variety that prefers 70 degrees in the same flat as a different variety that prefers 60 degrees. If plants have different light requirements for germination, no problem. Just cover the seeds that like darkness and don't cover the ones that require light.