MSU Extension

Cole crops

The word “cole” is where the shredded cabbage salad, cole-slaw, gets its name. This family includes, cabbage, Brussels sprouts, broccoli, cauliflower, collards, kale and kohlrabi. Grow these as spring or fall crops since that is when they grow best in Michigan and have the best flavor. Most cole crops can withstand frost and do not grow well in hot weather.

Cole crops that produce heads

Cabbage may be green or reddish-purple. There are early, mid-season and late varieties. Seeding to harvest takes 60 to 100 days, depending on the variety. Cabbage is usually grown from transplants. Savoy cabbage has attractive, crinkled leaves. There are also decorative cabbages used in flower gardens to add interest in the late fall that have colored or ruffled leaves and loose heads. They are edible, but not especially tasty.

Harvest cabbage when the heads are firm, like a small basketball or large softball. If left too long on the plant, the heads may split and flavor will decline.

Chinese cabbage and bok choy are cole crops grown for fall salad greens. Start seeds after mid-June. For best flavor, harvest heads when they are the size of a small bunch of celery.

Brussels sprouts resemble small cabbages growing as buds along the stem of the plant. These small cabbages grow in a spiral arrangement around stems that may reach two to four feet in height. The lower Brussels sprouts on the stem mature first, with multiple harvests going up the stem as the sprouts reach one to two inches in diameter. They are best grown as a fall crop and flavor will improve after a few light frosts. For larger sprouts, pinch out the growing point on the top of the stem in mid September. They are best grown from transplants.

Broccoli plants provide more than one harvest from each plant. The part you eat is the flower before it blooms. After removing the central head of broccoli from the plant, do not pull the plant out of your garden. Side shoots of small heads will develop after the central head is removed and will provide another harvest of small heads.

Harvest broccoli when the tiny buds in the head are dark green, before any of them open to a yellow flower. Cut the stalks off the plant about six inches below the top of the head, leaving the larger leaves on the plant. Broccoli raab, or sprouting broccoli, is grown for its many smaller sprouts and has a more pungent flavor.

Cauliflower grows best as a fall crop. It is another flower we eat, but one of the most difficult vegetables to grow, which may disappoint beginner gardeners. Produce a white head by pulling the leaves over the head when it is the size of a tennis ball. Then tie leaves together loosely with a string or rubber band. This is called blanching.

Harvest one to three weeks later when heads are six to seven inches across. Heads turn greenish-brown without blanching and the flavor is negatively affected. Some varieties, including those colored orange, green and purple, do not need to be blanched.

Kale, collards and mustard greens are non- heading cole crops grown mostly for cooked greens and decorative uses.

Kohlrabi, grown for its stem, has a short growing season because it should be harvested when young and in cool weather. Plant seeds in the early spring, and then every two weeks from late June to the end of July for a long harvest time. Harvest when the stem is swollen, tender and just above the ground. It should be no larger than a baseball. Large stems can get tough and woody. It is best peeled and eaten fresh as crisp slices, or grated into salads.

Radishes, turnips and rutabagas are root crops in the cabbage plant family with similar culture and pest problems. 

The basics

Cole crops do best with well-drained, moist soils that contain high levels of organic matter. Most soils benefit from adding compost to them each year. Keep plants weeded. Do not cultivate too closely because cole crops have shallow roots that can easily be damaged. Be sure to pull weeds when they are young before they become well-established.

Always follow soil test recommendations and package directions for fertilization. Use a high nitrogen fertilizer four to six weeks after transplanting, or when seedlings are two to three inches tall.

Many of the cole crops are more easily grown from transplants rather than direct seeding into the garden soil. Vegetables will be ready to harvest earlier if you plant transplants.

Keys to success