Set out cabbage seedlings in fall while the soil and air temperatures are still warm to start plants growing for harvest next spring.
• Spring cabbage started in fall will establish roots and begin top growth before freezing weather arrives then sit nearly dormant during winter then complete its top growth in spring before temperatures grow too warm for cabbage growing.
• Spring cabbage—a near misnomer because spring cabbage is commonly planted in autumn—will suffer from few of the pests and bolting that can plague cabbage planted in spring.
• Plant spring cabbage in soil that has been cleared of summer crops then amended with well-rotted compost and manure. Plant seedlings—there is not enough time to start cabbage from seed in autumn—in raised beds or at the top of ridges 4 to 6 inches above beds—higher in damp, low-lying gardens.
Sprinkle about 4 ounces of bone meal across every square yard of planting bed and turn it under or add a dusting of bone meal to the bottom of each planting hole.
Set out only seedlings that are strong with well-developed root systems. These plants will root into their new homes more quickly and begin growing without a struggle against cooling soil and air temperatures.
Get spring cabbage in the garden at least 6 weeks before the first expected hard front in fall—unless you plan to protect seedlings from freezing temperatures with a plastic tunnel or portable cold frame. Once plants are established you can protect them with spun-poly floating row covers or a mulch of straw or well-shredded dry leaves.
Set plants with their bottom leaves at soil level, firming them in with the heel of your hand and then watering. Side-dress (side-water) cabbage with a liquid fish-kelp solution every two weeks after planting.
To grow spring cabbage as a tasty spring green—that is to harvest leaves cut-and-come-again, not for heading—sow seed close together instead of setting out starts, much like growing mesclun. You can do this next spring or now if you live in a warm-winter region.
Where winter temperatures do not dip to freezing, grow heading cabbage through the winter just as you would if planting in early spring.
More tips at How to Grow Cabbage.