Loosen the soil to a depth of 12 to 15 inches with a spade or shovel, removing any rocks and large clumps or soil. Mix in a 2- to 4-inch layer of compost. Level the soil with a rake.
Sow seeds 1 inch apart and 1/2 inch deep. Set rows 12 to 18 inches apart. Sprinkle with water lightly until the soil is evenly moist.
Place a floating row cover, such as polyester or burlap, over the soil, letting the fabric slack in the center if it is directly on the ground or stretch tightly if it is supported by hoops. Push soil onto the edges of the fabric to help keep it in place. Keep the soil evenly moist until the seeds germinate.
Cut a few small, weak seedlings close to the ground with scissors when they are 1 to 2 inches tall, leaving the strongest seedlings. Thin the seedlings to 4 inches apart when they are 3 to 4 inches tall. Water the seedlings consistently two times a week to keep the soil moist, avoiding letting the soil dry out.