When should I harvest cole crops?
Cabbages are harvested when the heads are firm and solid. Sizes may vary, but firmness is the determining factor. If solid heads are left too long in the field to size up, they may crack or split. Cabbages should be sorted, packed, and stored according to size.
Cauliflower heads with white firm curds six to eight inches in diameter are what consumers prefer. Blanching, or tying the outer leaves, is done with certain varieties when the heads are about three to four inches in diameter, to keep sunlight from yellowing the curds. Curds should be handled carefully because they bruise easily and will develop discolored patches on these bruises. The surrounding trimmed leaves should be kept on the head for handling purposes to protect the curd. Some operations field-wrap the trimmed curds in cellophane or plastic bags before cooling and storing them in refrigeration.
Broccoli is harvested when most heads are tight, five to seven inches in diameter, and of a blue-green color. They are cut with a 6-inch stem. If left in the field, heads tend to loosen and expand, reducing quality. Fields should be harvested every three days, due to the rapid growth of this crop. Once the head is harvested, side shoots may develop from lateral axils on the stem, producing smaller inflorescences that may also be marketed.
Brussels sprouts produce many small buds in leaf axils along the entire stem. The lowest sprouts on the stem are picked first, along with the leaves, and harvest progresses upward as the other sprouts mature. Sprouts may crack if left on the stem too long.
Kale and collards are harvested leaves with petioles and are usually bunched together with a wire tie. Bunches are typically about eight to 14 inches long.
Kohlrabi should be harvested when the swollen stem is two to three inches in diameter. There are green and purple varieties. If left in the field for too long, the swollen stem becomes woody.
Chinese cabbage heads should feel solid and not collapse when pressed firmly with both hands. The wrapper leaves surrounding the cabbage should be stripped to leave only a couple to cover the firm head.
Pak choi can be harvested a few leaves at a time, cutting the outer leaves when they reach a desired size, or by harvesting the whole head. Some varieties are very brittle and should be left to wilt slightly to avoid breaking before packing.
You’ll benefit from reading the newly updated ATTRA publication Cole Crops and Other Brassicas: Organic Production. It addresses soils, fertility, planting, irrigation, pest management, harvesting, and marketing.