| By Patty G. Leander
Contributing Editor |
The Brassicaceae family is wide, wonderful and diverse. It includes sweet-smelling alyssum, fragrant stock, pungent arugula, sharp horseradish, peppery watercress and zesty radishes. Within this family are cabbage and its edible cousins from the genus and species Brassica oleracea, a venerated group of vegetables that contain powerful, health-promoting phytochemicals. Also known as cole crops, these cruciferous vegetables originated from an ancient, herbaceous mustard-type plant found growing along the rocky coast of the Mediterranean.
Originally harvested for its pungent leaves, this wild plant was gradually domesticated as farmers deliberately selected for desirable edible traits that we cultivate in our gardens today: the leafy greens of kale and collards, the flower buds of broccoli and cauliflower, the bulbous stem of kohlrabi, the terminal bud of cabbage and the axillary buds of Brussels sprouts. Despite the diversity of their edible parts, the familial similarities can be seen in the shape and texture of their large broad leaves (all of which are edible) and the four-petaled yellow flowers that, once pollinated, give rise to small dark seeds that develop inside narrow, oblong capsules called siliques.
These vegetables, with their thick, waxy leaves, are perfect specimens for the fall and winter garden in Texas. They grow well at temperatures between 45°–75° F, and gradual exposure to cold temperatures conditions the plants so they can handle a dip into the teens. If, however, an extended hard freeze is predicted, it would be wise to protect plants with frost cover or go ahead and harvest plants that are nearing maturity. With the exception of long-growing Brussels sprouts, these cole crops are ready for the table 60–90 days after transplanting. Most are biennials that are grown as annuals and harvested before they produce seed, but if they receive the necessary exposure to cold temperatures over the winter, some varieties will produce flowers the following spring. This period of cold exposure, called vernalization, is dependent on the weather, requiring several weeks of temperatures below 50° F to induce flowering. Most broccoli varieties are annuals, which fact explains their tendency to bolt into a riot of yellow blooms as the weather warms.
Brassicas will grow in a wide range of soils and they share similar cultivation requirements. Full sun is preferable for heading crops, especially during the winter season, when days are shorter. Leafy greens will tolerate a little shade and a successful crop is possible even with 4–6 hours of sunlight. Cole crops are heavy feeders, and so good soil preparation and fertility will get plants off to a good start. Amend soil with a 2-inch layer of compost along with a granular, all-purpose vegetable fertilizer, following label instructions. Plant transplants 10–12 weeks before the first freeze in fall; water in with a starter solution and continue to feed with a high-nitrogen fertilizer or fish emulsion every 3–4 weeks to encourage steady growth.
It’s important to recognize that heading crops must be kept actively growing to produce large leaves on vigorous plants in order to support the formation of heavy, well-developed heads. Plants that are stressed by too little water, too much cold or low fertility can stunt the development of the head. This condition, called buttoning, is irreversible. No amount of water or fertilizer will coax a head out of a stunted plant. When buying transplants, look for stocky seedlings grown in 3- or 4-inch containers. Transplants that have already begun to produce a head are generally a lost cause, an indication they have spent too much time in the container.
Follow the spacing recommendation when setting transplants in the garden. As a general rule, allow 18–24 inches between plants for adequate development. The more generous spacing will result in larger leaves and a bigger head. Compact varieties developed for container culture or small-space gardens can be positioned closer together.
Transplants of new introductions or unique heirlooms are sometimes hard to find at local nurseries, but it’s easy to grow your own from seed and only takes 4–6 weeks to reach transplantable size.
Broccoli. Grown for large heads composed of tight clusters of flower buds, heading broccoli is a fall favorite. Once the central crown is harvested, the plant will continue to produce smaller lateral side shoots. ‘Arcadia’, ‘Belstar’ and ‘Green Magic’ tolerate cold and provide a plentiful harvest of secondary side shoots. Older varieties of Italian descent, such as ‘Calabrese’ and ‘De Cicco’, are known as sprouting broccoli. Rather than a large central head, they produce a season of tender florets atop slender stalks.
Cauliflower. The cluster of immature buds that form a cauliflower head is called a curd. The curd can be white, green, purple or orange, with white the most common and familiar color. Snowy-white cauliflower is the result of blanching to shield the developing curd from the sun. Some cauliflowers are self-blanching, with leaves that naturally fold inward to cover the head, while other varieties are blanched by wrapping or tying up the outer leaves. This can be done using a clothespin, rubber band or twine when the curd is about 3–4 inches in diameter. Colored varieties do not need to be blanched.
Cauliflower is sensitive to weather extremes, and prolonged exposure to freezing weather leads to off-color or misshapen heads. Frost cloth used during a hard freeze can provide the protection cauliflower needs to survive unaffected. Improvements by plant breeders have led to the introduction of hybrid varieties that are faster to mature and less susceptible to temperature extremes, resulting in a more successful crop for Texas gardens. ‘Amazing’ and ‘Snow Crown’ are white, self-blanching varieties. For colored heads, try purple ‘Graffiti’, green ‘Vitaverde’ or orange ‘Flame Star’. Another unique green variety is an Italian heirloom called ‘Romanesco’, a striking pyramid of pointed spirals, sure to turn heads in the garden and at the table.
Cabbage. From compact mini-heads to crinkled savoys to anthocyanin-packed reds, cabbage is as diverse and interesting as any other brassica. The many varieties available add color, texture and form to the garden from fall to spring. Early-season varieties mature about two months from transplanting to midseason, whereas late varieties can take up to three months. Harvest window can be extended by choosing varieties that mature at different rates. Cabbages have a tendency to split if allowed to over-mature, so be sure to note the approximate size and days-to-harvest for whatever variety you decide to grow. For an early harvest of two- to three-pound heads, try ‘Farao’, ‘Red Express’ or savoyed ‘Alcosa’. ‘Early Jersey Wakefield’ is a popular heirloom from the mid-1800s that produces conical heads on compact plants. ‘Deadon’ is a beautiful, cold-hardy savoy type; light-green leaves are flushed with purple.
Brussels sprouts. Grown for the small buds that develop at leaf axils along the stalk, Brussels sprouts have become a popular garden crop and are well-suited to the fall and winter months. They grow over a long season, and exposure to frost helps develop a better flavor. Diminutive sprouts develop at the base of the plant first, gradually spiraling upward as the plant matures. Cut or twist to harvest sprouts when they are no bigger than a golf ball; removing the lower leaves will make harvesting the sprouts easier. ‘Hestia’ is a hybrid 2015 All-America Selections winner prized for its uniform growth habit and cold tolerance. ‘Autumn Star’ Kalettes, a recent breeding innovation involving a hybrid cross between Brussels sprouts and kale, results in lovely, open florets that develop along the stalk.
Collards and kale. Direct-seeded or grown from transplants, these cabbage cousins produce nutritious leaves in shades of green, blue-green and purple. Cold-hardy and attractive, collards and kale are among the easiest brassicas to grow. Versatile in the kitchen, the leaves can be harvested at varying sizes: small and tender for salads, mid-size for wraps or fully mature for a hearty pot of Southern greens. Harvest individual leaves from the base of the stalk as needed, or the entire plant can be harvested by cutting it off just above ground level. Crinkled kale favorites include blue-green ‘Starbor’ and deep purple ‘Redbor’, both reaching 2–3 feet in height. ‘Lacinato’ kale goes by many names, including ‘Toscano’, ‘Cavalo Nero’ and dino kale. An Italian heirloom that dates to the late 1800s, it is a favorite of foodies and gardeners alike. It is prized for its narrow, puckered leaves that grow on striking 3-foot plants.
In contrast to frilly kale, the leaves of collards are thick and smooth. Classic favorites include ‘Champion’ and ‘Georgia Southern’, but all varieties seem to grow well in Texas. One of my favorite heirloom collards is ‘Green Glaze’. It tolerates heat, is slow to bolt in spring, and its slick, bright-green leaves seem somewhat resistant to caterpillars.
Kohlrabi. The edible part of kohlrabi may look like a turnip, but it is actually a bulbous stem that develops above ground at the base of the leaves, which are also edible. Light-green or purple on the outside, the interior is crisp and creamy white, with a mild, sweet flavor that hints at its kinship to cabbage. Kohlrabi can be seeded directly in the garden, at intervals one-to-two weeks apart to extend the harvest. For best flavor and texture, harvest when not much larger than a golf ball; a delay in harvesting may lead to a bitter flavor and woody texture. Purple-skinned varieties include ‘Kolibri’ (an improved, uniform hybrid) and ‘Azur Star’ (a popular open-pollinated variety). ‘Early Green Vienna’ and ‘Early Purple Vienna’ are widely adapted heirlooms that have been grown in the United States since the 1860s.
As soon as your defenseless transplants get set out in the garden, they will be discovered by a number of pests, especially caterpillars, cutworms and aphids. Protecting plants with row cover will exclude these pests and also provide a little protection on cold nights. Cover plants immediately after planting and secure the edges with soil, rocks, boards or U-shaped pins.
Additional treatment includes regular spraying with insecticidal soap for aphids and Bt for control of caterpillars. Cutworms will curl around the base of tender, new transplants and cut them off at the ground, but you can foil such devilment by placing a physical barrier, like a stick, toothpick or a sliver of plastic straw, right next to the stem.
One of the many benefits of growing your own vegetables is eating them at their peak. As you anticipate the coming harvest, think about how you plan to incorporate your prized produce into your meals. Stinky boiled brassicas are out; instead consider roasting, grilling, stir-frying, pickling and raw preparations. Combine with complimentary flavorings: the saltiness of bacon, soy sauce or Parmesan cheese; the spiciness of fresh chiles or red pepper flakes; the tang of apple-cider vinegar, mustard or lemon. Cookbooks, blogs and cooking magazines are packed with creative and delicious recipes sure to whet your appetite.
