When should I harvest cabbage?
The harvest of cabbage may begin when the heads are firm and the size of a softball. Mature cabbage should be harvested when the heads are solid and tight, before they crack or split. Splitting is caused by excessive water uptake; the resulting pressure splits the head. Splitting of mature heads may be prevented by pulling the plant upward and gently twisting. Some of the roots will be broken, thereby reducing water uptake.
Cabbage may be placed in a perforated plastic bag and stored in the refrigerator. A cool, moist (32 degrees Fahrenheit, 98 to 100% relative humidity) storage site is required for prolonged storage up to 3 to 4 months.