Seed Starting

Starting seeds indoors gives you a head start on the season, more variety than a garden center offers and stronger plants for less money. Success comes down to four things: light, warmth, a good seed-starting mix and a tray that drains well.
Light is the most common problem. Windowsills often don’t give seedlings enough, so they stretch and fall over. A full-spectrum LED hung a few inches above the plants and run on a timer fixes that. See our guide to the best grow lights for seedlings.
Seed-starting soil should be light, fine and sterile. Garden soil is too heavy and may carry disease. Compare the best seed-starting soils for texture and moisture retention.
Trays and kits make the setup easier. Cell trays keep roots separate for easy transplanting, and a humidity dome holds moisture until seeds sprout. Browse the best seed-starting trays and seed-starting kits.
Check your seed packet for the planting date, usually six to eight weeks before your last frost for many vegetables. Keep the mix evenly moist, and use a fan or open the dome once seeds sprout.
Harden off seedlings before planting them out: give them a few hours of outdoor shade, then more sun each day over a week. This toughens the leaves and prevents shock when plants meet real sun and wind.
Label everything. Seedlings of different crops look alike, so a simple stake or tag with the variety and sow date saves guesswork. Keep notes on what germinated well, and you will plan next season far more easily.
Thin crowded seedlings early. Snip the weakest ones at soil level, leaving the strongest in each cell, so roots have room and air can move between leaves, which also lowers the risk of damping off.
Warmth speeds germination. Many seeds sprout best in a mild, steady spot, so a heat mat under the tray can help, but remove it once seedlings appear so the young plants do not overheat.