Companion planting: Thyme, peppermint, sage, and rosemary will deter cabbage worms; beets, beans, lettuce, ...
Bad companions: Garlic, ground cherry, chives, pumpkin, tomato, ...
You should start your cabbage seedlings 8 to 12 weeks before the last expected frost by planting them at ½'' in individual pots. Plant them in the garden 2 or 3 weeks before the last expected frost, leaving a spacing of 12 to 18 inches. Be sure to bury the stems halfway.
Danish Cabbage prefers cool weather, but in case of heavy frost, cover your plants. Mulch them to regulate soil temperature and retain moisture, as overly dry soil could cause the cabbage to split.
Harvest the cabbage as soon as they are firm and reach a good size. Small cabbages tend to be more tender, while large fall-growing cabbages store well over the winter.