Cool Fall Weather Brings Sweet Cole Crops

September is the best time to harvest cole crops like cabbage, cauliflower, broccoli, kohlrabi, and Brussels sprouts.

Cool weather retards respiration, allowing plants to accumulate sugars for a sweeter taste. Cole crops planted in the spring that mature in hot weather tend to have a stronger taste. Plant growth is also slower in the fall, which results in less cracking of cabbage heads and Brussels sprouts.

Cabbage head maturity varies more than other types of cole crops. Maturity of open-pollinated cabbage varieties can vary as much as a month, allowing gardeners to spread out the harvest season. Hybrid varieties tend to mature uniformly.

Begin harvesting cabbage when heads are firm and weigh at least 2 to 3 pounds. Late-maturing varieties can weigh up to 8 pounds or more.

Cauliflower is grown for its swollen flower-stem. The white, tender head is formed from short, thickened flower parts. As the small curd or button begins to develop, tie the outer leaves that surround the curd together over the developing head with twine or rubber bands to protect it from light. Don’t tie the leaves too tightly or the head will collect moisture and cause mold. But make sure the leaves exclude all light or the head will turn yellow. Harvest curds at about 6 inches in diameter when the curd is still tight. Cut the stem below the head, leaving a few trimmed leaves to protect the curd.

The most popular type of broccoli is the sprouting form. It’s more nutritious than other cole crops. The branched flower buds that form on the top of the plant are dark green and very compact. Harvest the buds before they spread apart and before the individual buds begin to open. The buds form a compact, domed head to protect it from fall rains.

The swollen stem of kohlrabi is edible. White, green or purple stems of developing kohlrabi plants swell above the soil surface, eventually forming a globe with leaf petioles attached at regular intervals on the surface. Under optimum conditions, globes can reach 3 inches in diameter.

Brussels sprouts take longer to mature than other cole crops and are normally direct-seeded in the garden in May. Small auxiliary heads or sprouts form along the main stem during the fall. Early sprouts that appear in warmer weather tend to form loosely and crack. In cooler weather, sprouts become more compact.

Sprouts mature from the ground up and form in the axils of leaves. Remove the leaves when harvesting. About two to three weeks before hard frost, remove the tip of the plant to force plant energy into maturing all the remaining sprouts.

For more information, please visit New Mexico State University's Cooperative Extension Service (CES) Publications website.