The sweet and mild taste of homegrown cauliflower more than justifies the extra care it requires. In general, cauliflower is not difficult to grow, but it is sensitive to extreme temperatures. Primarily a cool-weather crop, cauliflower won’t produce heads in hot weather and is frost-tolerant only as a mature fall crop. Most cultivars need about 2 months of cool weather to mature, though some require as little as 48 days and others over 95 days. To grow cauliflower successfully, the key steps are to choose the right cultivar for your climate, plant at the proper time, and provide a steady supply of moisture.
Planting: Like other cabbage-family members, cauliflower needs a soil rich in nitrogen and potassium, with enough organic matter to retain moisture. In warm climates, plant in fall or late winter for an early spring harvest. In colder areas, cauliflower usually performs best as a fall crop.
To avoid disturbing roots, start cauliflower seedlings indoors in peat or paper pots. Plant seeds ¼ to ½ inch deep, 4 to 6 weeks before the last average frost. Provide constant moisture for seedlings but avoid waterlogged soil; use bottom heat, if necessary, to keep the soil temperature around 70°F.
Harden off young plants gradually before transplanting them to the garden. Set the seedlings 15 to 24 inches apart. Make a saucerlike depression around each plant to help hold water. Firm the soil, and water seedlings thoroughly. Cover beds with floating row cover to prevent insect pests from damaging tender transplants.
Growing guidelines: Provide at least 1 inch of water a week, soaking the soil to a depth of 6 inches. Cauliflower requires constant moisture to produce large, tender heads; soil that dries out between waterings will cause heads to open up and become “ricey.” Use a thick layer of compost or organic mulch to cut down on evaporation and weeds and to cool the soil. Be careful not to disturb cauliflower roots when weeding, because damaged roots produce uneven growth. Give young plants monthly light feedings with fish emulsion or compost tea. If you want to speed up growth, feed every 2 weeks. See the Compost entry for instructions for making compost tea.
When the flower heads (curds) of white-headed cultivars are about the size of an egg, blanch them by shading out the sunlight. Otherwise they’ll turn yellowish or brown and become, if not less tasty, certainly less appealing. Prepare plants for blanching on a sunny afternoon when the plants are totally dry, because damp heads are more susceptible to rot. Just bend some of the plants’ own leaves over the head and tuck them in on the opposite side, or secure the leaves at the top with soft twine, rubber bands, or plastic tape. Use enough leaves to keep out light and moisture, but allow room for air circulation and for the heads to grow.
Once the blanching process begins, be careful to avoid splashing water on the heads or leaves. Unwrap occasionally to check on growth, to look for pests, or to allow heads to dry out after a rain. In hot weather, heads can be ready to harvest in a matter of days. In cool periods, the maturing process can take as long as 2 weeks. Blanching is not necessary when you’re growing varieties that produce purple, lime green, or orange heads, or with self-blanching types, which have leaves that naturally curl over the head.
Problems: Pests—such as aphids and flea beetles—tend to attack cauliflower more in spring than in fall. Cabbage maggots, sometimes called root maggots, can also be a serious problem. Caterpillars, such as cabbage loopers and imported cabbageworms, are other common cauliflower pests.
In boron-deficient soil, cauliflower heads turn brown and leaf tips die back and become distorted. If this occurs, foliar feed with liquid seaweed extract immediately, and repeat every 2 weeks until the symptoms disappear. For subsequent crops, provide boron by adding compost to the soil, or plant fall cover crops of vetch or clover.
Crop rotation, good garden sanitation, and using resistant cultivars will prevent most cauliflower diseases. These include black leg, black rot, club root, and Fusarium wilt (yellows).
If your cauliflower heads taste bitter, chances are the problem was lack of moisture or some other factor that slowed the growth of the plants. For your next crop, be sure to plant in soil with plenty of organic matter, keep the soil surface mulched, and water regularly.
Harvesting: Mature cauliflower heads can range in size from 6 inches to 12 inches across. Harvest when the buds are still tight and unopened. With a sharp knife, cut them off just below the head, along with a few whorls of leaves to protect the curds. Use or preserve right away. Note that cooking will cause the color of orange, green, and purple cauliflower florets to fade.
If you don’t have time to harvest your crop before a heavy frost strikes, remember that the heads will still be edible unless they thaw and freeze again. Cut the frozen heads and cook them right away. To store plants for about a month, pull them up by the roots and hang them upside down in a cool place.