Some gardeners in the South plant a spring crop, harvesting the lower leaves as they need them early in the season. Then they simply keep the plants growing through the hottest months, and begin harvesting again in the fall. It's much more common, though, to plant collards twice, in early spring and again in late summer. Start collards indoors six to eight weeks before setting them out in the garden, which you can do as early as four weeks before the first frost-free date if plants are properly hardened off. If you plant collards in wide rows, thin them so that the plants will be eight to 10 inches apart.
Collards can also be direct seeded three to four weeks before the last frost-free date in spring.
Fall plantings should go in 10-13 weeks before the first fall frost date. Cool fall nights and light freezes will put zing and succulence into the leaves. Like other greens, you can start harvesting collards as soon as some of the leaves make enough for a meal. The fast-growing greens of the Chinese cabbage family are nearly ideal garden vegetables for spring, summer, and fall. Versatile enough to be enjoyed boiled, sauteed, and stir-fried as well as fresh, they lend a sprightly, nutty, or sharp flavor and succulent texture wherever they appear.