Wait until approximately one month before the date of the last frost to plant cabbage for a summer harvest, or until June or July for a fall harvest. Do not wait until the middle of the spring for a summer harvest, because the cabbage will reach maturity when the summer temperatures are too hot, which could affect the quality of the cabbage.
Plant the seeds or seedlings in a row 12 inches apart on all sides and 1/4 to 1/2 inch deep.
Spray the seedlings with a starter fertilizer once just after planting. When the cabbage plants are halfway grown, after approximately one month, feed the plants again with a nitrogen-rich fertilizer.
Water the plants regularly so that the soil is consistently moist but not muddy. Constant moisture is needed to ensure that the cabbages heads don't crack.
Harvest the cabbage any time after the heads form, when they are round and firm. Cut the heads at the base of the soil with a sharp knife.