Or sow a few seeds in the coldframe or garden every month to have cabbage plants after that. It takes four or five weeks to grow plants from seed to transplant during the summer months. It is best not to plant cabbage family crops in the same spot year after year, since diseases and insect pests build up. Rotate crops within your garden. Plant spacing affects head size.
Cabbage is harvested when it reaches adequate size, depending on variety and growing conditions.
Firm heads are preferred, especially for storage. Plant six weeks before the last hard freeze date. Many varieties are available, and two or three varieties provide harvest over a long period. Hardened plants are tolerant of frost and can be among the earliest planted garden vegetables. Late cabbage must be started during the heat of midsummer, but it develops its main head during the cool weather of fall.