Start cabbage seeds indoors 6 to 8 weeks before the last spring frost. See frost dates for your area.
Harden off plants over the course of a week. To prepare soil, till in aged manure or compost.
Transplant outdoors 2 to 3 weeks before the last expected frost date. Choose a cloudy afternoon.
Plant 12 to 24 inches apart in rows, depending on size of head desired. The closer you plant, the smaller the heads.
Mulch thickly to retain moisture and regulate soil temperature.
Practice crop rotation with cabbage year to year to avoid a buildup of soil borne diseases.
-Source: Old Farmer's Almanac