A late autumn planting of "calabrese" broccoli matures in Steve's vegetable garden.
Broccoli and cauliflower are two derivatives of cabbage, both selected for their edible, immature flower heads. Broccoli is grown for the clustered green (or purple) flower buds that are picked before they open and eaten raw or cooked. There are three main types of broccoli. The typical green or purple broccoli with one large, central head is a "calabrese". "Romanesco" broccolis have flower buds grouped in numerous small cone-shaped heads, arranged in spirals; the "sprouting broccolis" (sometimes placed in a different group or variety within B. oleracea) produce a succession of small flowering heads over an extended season.
The cauliflower head is a cluster of aborted, malformed flower buds that stopped developing in the bud stage. Cauliflowers come in white, lime green and purple varieties. Both cauliflower and broccoli will produce viable flowers and seed pods if left in the ground through the cool season and into the warmer weather and lengthening days of spring or summer.
Wild cabbage (Brassica oleracea ssp. oleracea), the progenitor of all the Brassica oleracea varieties, grows along the coasts in Europe and north Africa. It is believed that broccoli and cauliflower were developed from a cabbage ancestor by gardeners in the eastern Mediterranean just three or four hundred years ago. Broccoli and cauliflower are (relatively speaking) very recent additions to our vegetable larder.
Broccoli is easy to grow in cool weather, but it is not as tolerant of frost (or hot weather, either) as cabbage, collards and kale. Cauliflower is more difficult to grow. Too much cold, too much heat, not enough water, too much water, not enough lime, or too much nitrogen, and you end up with small, misshapen or rotted heads. Cauliflower is less frost-hardy than broccoli, and less tolerant of high temperatures, too. Cauliflower requires a higher pH (around 7.0) than other brassicas.
Light: Full sun.
Moisture: Regular garden watering. Don't let the soil under broccoli or cauliflower dry out. Cauliflower is especially sensitive to drying. Mulch, mulch, mulch! Hardiness: Both broccoli and cauliflower are grown as cool season annuals. They do best with temperatures around 60ºF (15.6 ºC). Both can tolerate light frosts and temperatures down to 25ºF (-3.8 ºC) or so. But long days and warm nights will cause broccoli to flower quickly, and cauliflower to deteriorate. Most broccoli cultivars take 50-70 days to mature and cauliflower cultivars 60-90 days. In USDA zones 8B-10, broccoli and cauliflower are grown in the winter. Gardeners in zones 6 through 8A can plant in early spring and again in early autumn. Elsewhere, broccoli and cauliflower are planted in early spring. Propagation: Both broccoli and cauliflower are propagated from seeds, which usually germinate in about a week. Most home gardeners purchase seedlings to set out when temperatures are favorable, and save 3-4 weeks of growing in the garden.
The edible portions of the cauliflower are the plant's blanched, malformed flower buds which is probably not the most appetizing description for what we think is a mighty tasty vegetable!
Many of the broccoli cultivars grown in the home garden will sprout new, side heads after the main, central head is cut off. Cauliflowers usually don't do that. Some cauliflower cultivars are self-blanching, with leaves that grow upward and partially shade the head; other cultivars should be blanched by tying up leaves loosely around the developing head. Purple cauliflowers don't need to be blanched. Both broccoli and cauliflower must be harvested early. Broccoli will quickly flower and cauliflower heads will crack, become discolored, or rot if not harvested as soon as mature.
Broccoli and cauliflower are at their best when eaten raw or cooked as little as possible.
Broccoli may be the most nutritious of all the cole crops, which are among the most nutritious of all vegetables. Broccoli and cauliflower (and other members of the genus Brassica) contain very high levels of antioxidant and anticancer compounds. Vitamins and nutrients typically are more concentrated in flower buds than in leaves, and that makes broccoli and cauliflower better sources of vitamins and nutrients than cole crops in which only the leaves are eaten. The anti-cancer properties of these vegetables are so well established that the American Cancer Society recommends that Americans increase their intake of broccoli and other cole crops. Recent studies have shown that broccoli sprouts may be even higher in important antioxidants than the mature broccoli heads. Other research has suggested that the compounds in broccoli and other brassicas can protect the eyes against macular degeneration, the leading cause of blindness in older people.
The botanists cannot agree on the taxonomy of broccoli and cauliflower. Some authorities place broccoli in a separate group (cymosa) from cauliflower (botrytis). Some authorities place the sprouting broccoli cultivars in a third group, italica. And some authorities place them all in the same group (botrytis), as we have done here. And whether these categories are called "groups", "subspecies", or "varieties" also depends on whom you ask! Turnip broccoli (a.k.a. broccoli raab) belongs to another species altogether: Brassica rapa, var. ruvo.
See Floridata's cabbage profile for a listing of the varieties (or groups) of B. oleracea, and the mustard profile for a partial listing of the edible species within the genus Brassica.