You may think of them more readily as members of the cabbage clan, but whatever you call them, the brassicas -- also called crucifers or cole crops -- are some of the most nutritious and tasty crops you can grow. One species in the genus Brassica is especially bountiful in the vegetable garden -- Brassica oleracea includes broccoli, Brussels sprouts, cabbage, cauliflower, kale, and kohlrabi. All of these veggies are not only delicious on the plate, they are loaded with vitamins, minerals, fiber, and other important phytonutrients, antioxidants, and healthful omega-3 fats. So be sure to include this beneficial bunch in your garden planning for next season.
How is it that plants as different kale and Brussels sprouts are members of the same species? Although all are in this same botanical category, their diversity is found in cultivars or cultivated varieties, all of which have been bred and maintained by the hand of man over generations.
Regardless of their diverse looks, all of the brassicas like similar growing conditions, especially cool temperatures. So these crops are great for spring and fall planting, even winter crops in warmer parts of the country.
Here are just some the many brassicas we offer to try in your garden:
'Long Island Improved' Brussels Sprouts (90 days) - Grown chiefly as a fall crop, this uniform variety has an unusually fine flavor.
'Calabrese or Green Sprouting' Broccoli (85 days) - Bluish-green, 3-5 inch diameter heads form on this open-pollinated variety.
'Copenhagen Market' Cabbage (70 days) - A good early market and home garden variety with uniform, crisp, tender, 4 to 4 1/2 pound heads.
'Red Russian' Kale (50 days from transplant) - Deep gray-green leaves with purple veins are flat with deeply cut margins and have a sweet, mild flavor.
'Early White Vienna' Kohlrabi (55-60 days) - Forms fine textured, green bulbs that taste best when 2 inches in diameter.
'Red Acre' Cabbage (74-90 days) - A sure heading variety with deep red-purple, 5-7 inch diameter heads weighing 2-4 pounds.
While you can direct seed broccoli right in the garden, success is more assured if you start seeds indoors and transplant seedlings to the garden when they are large enough to better weather insects pests and outdoor temperatures. Start seeds 6 to 8 weeks before the last frost date in your area; transplant hardened off seedlings into the garden two weeks before the the last frost date. For a fall crop, sow seeds 10 to 12 weeks before the first fall frost date. Gardeners in mild winter climates can sow succession crops in the fall for harvest throughout the winter.
Broccoli is a heavy feeder so work a few inches of organic matter into the soil before planting. Soil pH between 6.0 and 7.2 is ideal. Space seedling 15-18 inches apart and set them slightly deeper than they were growing in the container, up to their first set of true leaves. Protect the stem of each plant with a cutworm collar. The simplest way is to wrap the seedling stem with 2- to 3-inch strips of newspaper. Cover the seedlings with a floating row cover to prevent damage from flea beetles and cabbage worms. If the temperature dips below 50 degrees for more than one night, add some extras layers of row covers to prevent chilling injury.
Broccoli is ready to harvest as soon as the head, which is actually a cluster of unopened flower buds, is of a usable size and has a deep green color. Cut the main head with a 2 inch stem, then check for the formation of smaller side shoots that will extend your harvest.
Like broccoli, cabbage is best started indoors and set into the garden as transplants. Start seeds in spring 6 to 9 weeks before the last spring frost, transplanting them to the garden 1 to 3 weeks before the last frost. Sow seeds for a fall crop about 12 weeks before the date of the first hard frost, transplanting them out about 6 weeks later. Space seedlings 12 to 24 inches apart, depending on the mature size of the variety you're growing.
As with broccoli, cutworms collars and row covers will help prevent pest problems. And be sure to give cabbage seedlings some extra protection if temperatures dip below 50 degrees for more than a day or two.
When cabbage heads are hard and firm and about the size of a softball, you can begin harvesting or let them mature to their full size. If you cut the heads of spring cabbage leaving as much stem as possible, several buds may begin to sprout at the cut. Cut off all but one and you'll harvest a second, smaller head of cabbage later in the season.
Fast-growing kohlrabi does best when the weather is cool. It can be grown as a spring crop and also makes a good fall crop in many parts of the country. In the spring, sow seeds outdoors 4-6 weeks before the last frost date and make repeat sowings every week or two while the weather remains cool. For a fall crop, sow seeds directly in the garden 8 to 10 weeks before the first expected fall frost date. In warm winter areas (Zones 9 and 10), you can make repeat sowings during the fall for harvest in the winter and early spring.
The best advice about harvesting kohlrabi is not to wait too long. Most varieties are ready for harvesting just 6 to 7 weeks from planting and are the most tender and flavorful when the bulbs are 2 to 4 inches in diameter. Fall crops that ripen in cool weather don't get woody as readily and can be picked at little larger size, up to 5 inches across.
This is perhaps the most finicky of the brassicas to grow, cauliflower doesn't take stress well. It's a little like Goldilocks -- it wants temperatures that are not too hot, but not too cold; soil that is fertile, but not too high in nitrogen; soil that is moist, but not too wet or dry. It also need careful transplanting when it's not too young but not too old -- between 4-6 week old seedlings work best. In many parts of the county, cauliflower works best as a fall crop, since transplants set out when temperatures are in the 50s (any earlier and the heads may "button" and remain tiny) may be ripening when the weather is too hot for their liking. Sow seeds for a fall crop about 75 days before your expected fall frost date.
Brussels sprouts taste sweetest when they have been touched by frost, making them a great fall crop. So take your time getting your seeds sown -- wait until you've gotten your warm weather crops like tomatoes and peppers in the ground. Pick your sprouts from the bottom of the stem upward. beginning as soon as they are large enough to eat (about 3/4-1" in diameter, with tightly curled leaves). As you harvest, remove the leaf associated with the sprout. To harvest, cut the little heads off with a sharp knife. If your sprouts are starting to "unfurl", they may not taste as good.
Kale is another crop that tastes best after frost. For a sweet-tasting fall harvest, start your seeds about 10-12 weeks before your fall frost date. Check your plants regularly for aphids, which can have a population explosion toward the end of the season. Knock them from plants with a strong stream of water or use a low-toxicity spray such as insecticidal soap to bring these pests under control.
Q: What's the trick to growing a successful crop of Chinese cabbage?
A: Although it's in the Brassica genus, Chinese cabbage is actually more closely related to turnips than to regular cabbage. Chinese cabbage does best if it's direct-seeded. Sow seeds as soon as the soil can be worked for a spring crop. Chose a bolt-resistant variety for spring sowings. A fall crop of Chinese cabbage is often easier to grow, being less likely to bolt due to warm weather. Sow seeds 12 weeks before the first fall frost date. Harvest when young and tender by either cutting individual leaves or the entire head.
Article published on December 4, 2013.