Collard, mustard and turnip greens are all part of the same family, but each has a different flavor. Most gardeners grow greens from seed sown directly in the garden.
Greens like well-worked soil with lots of organic material. Use a garden fork to work a mixture of humus and composted manure deep into the soil. Add approximately one cup of slow-release fertilizer to cover a 4' x 9' garden bed and work it into the soil.
Greens can be sown in the ground as soon as it can be worked in early spring. Plant seeds 1/2" deep and 2" apart in rows spaced at least 18" apart. Cover the seeds with soil and water well. Place row markers to indicate which variety of greens was planted where. Cover the bed with a floating row cover to speed up germination.
When seedlings sprout, thin plants to one every 8" by cutting them off at ground level with clean shears. As the weather warms and the greens grow larger, remove the row covers. Water plants during extended dry periods to maintain adequate moisture levels. Keep a constant lookout for pests like aphids and cabbage worms, removing and destroying them as quickly as possible.
Greens generally reach maturity in 40 to 70 days. Harvest just the leaves you wish to eat from the outside of the plants. If plants grow so large that they begin to touch, harvest entire heads to make room. Harvest entire plants before the heat of summer decreases the flavor and quality of the leaves.