Prep the Planting Tray

Fill a planting tray with moist seed-starting mix, usually a soil-less product that combines perlite, vermiculite and peat moss.

Sow the Seeds

Sow the seeds 1/4 inch deep, firming the moist seed-starting mix over the seed. Place one seed per plug if your seed tray has inserts that hold the mix in separate 1- to 2-inch compartments. Otherwise sow seeds a few inches apart so seedlings will be easy to remove later.

Keep Them Warm

Set the tray on a waterproof greenhouse heat mat set to 68 to 72 degrees Fahrenheit or in a room with the same temperature range.