Vegetables must be harvested at the proper stage of maturity in order to obtain the highest quality produce. The harvest and storage recommendations for broccoli, cauliflower, cabbage, and other cole crops are listed below.
Broccoli. Harvest broccoli when the terminal head is fully developed, but before the buds begin to open and yellow flowers appear. At harvest, the head should be tight, blue-green, and approximately 6 inches in diameter. Many broccoli cultivars will produce several smaller side heads (about 1 to 3 inches across) in the axils 
of the leaves after the central head is removed. Broccoli may be placed in a perforated plastic bag and stored in the refrigerator for up to 7 to 10 days.
Brussels Sprouts. One or more light frosts improve the favor of Brussels sprouts. Harvest individual sprouts or buds from the base of the plant as they become solid. Buds should be 1 to 1½ inches in diameter and tender and green. Remove buds higher up on the plant as they become firm. Do not strip the lower leaves from the plant as they are necessary for further growth. Sprouts may be placed in a perforated plastic bag and stored in the refrigerator for up to 3 to 5 weeks.
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 heavy. Large heads are prone to splitting if not harvested promptly. To reduce the incidence of splitting and delay or stagger harvest, pull the plant upward and gently twist to break some of the plant’s roots and reduce water uptake. After harvest, remove the loose cover leaves and store the heads in perforated plastic bags in the refrigerator for 2 to 4 weeks.
Cauliflower. Harvest cauliflower when the heads are 6 to 8 inches across, but still compact and smooth. Over-mature heads begin to open up and become grainy in texture and appearance. Cauliflower can be stored up to 2 weeks in perforated plastic bags in the refrigerator.
Collards. Periodically harvest the larger, lower leaves or cut off the entire plant near ground level. Leaves can be placed in perforated plastic bags and stored in the refrigerator for up to 10 to 14 days.
Kale. Periodically harvest the older, outside leaves or cut off the entire plant near ground level. Leaves can be placed in perforated plastic bags and stored in the refrigerator for up to 10 to 14 days.
Kohlrabi. Harvest kohlrabi when the thickened stems are 2 to 3 inches in diameter. (Kohlrabi that are larger than 3 inches in diameter will be tough, woody, and bitter.) Remove the leaves and roots and store in perforated plastic bags in the refrigerator for up to 3 weeks.
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