It's much more common, though, to plant collards twice, in early spring and again in late summer. In the South, collards are so widely grown that garden stores and nurseries provide young collard plants for sale at planting time. Setting out these plants is a convenient and pretty reliable way to have a good harvest before hot weather slows things down. 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 to 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. Vates' and 'Champion' are good varieties for the home gardener. The former tolerates cold weather well, while the latter does well in the heat.