How to Grow Cauliflower

Why cauliflower is harder than broccoli

Clemson Extension calls cauliflower the most sensitive of the cole crops to adverse conditions. The head, or curd, is a mass of undeveloped flower buds, and it reacts badly to heat, cold, drought and hunger. Utah State says cauliflower grows best when temperatures stay below 75°F, and that both freezing temperatures and temperatures above 80°F reduce growth and head quality. Iowa State reports that days of 86°F or more with nights of 77°F or more can prevent a head from forming at all. Clemson’s preferred average is 60 to 65°F. Every step below is about keeping the plant growing steadily through a cool heading period.

When to plant

In spring, set transplants out around the dates for your zone above. Sources disagree on how early: Utah State plants 1 to 2 weeks before the last frost, while Maryland Extension plants 3 to 4 weeks before. The earlier date gives more time before summer heat; the later one lowers the risk of a cold spell. Clemson notes that 10 or more days between 35 and 50°F after a period of good growth can make cole crops bolt, and Maryland warns that planting too early is one cause of buttoning.

Fall is often the better season. Maryland says mid-Atlantic gardeners generally succeed more with fall cauliflower, sowing seed in early July and transplanting from late July to early August. Penn State recommends late July or early August plantings, and Iowa State sets transplants out in early to mid-July. Utah State suggests early-maturing varieties planted 50 to 75 days before a harvest about 1 to 2 weeks after the first fall frost.

In zones 9 to 11 cauliflower is a fall and winter crop. UF/IFAS lists planting windows from fall into winter in Florida and calls it difficult to grow there. In the Lower Rio Grande Valley of Texas, Texas A&M AgriLife times it like broccoli, with transplants set out from mid-October. West of the Cascades in Oregon and Washington, Oregon State’s PNW 548 describes overwintering cauliflower, transplanted from mid-July to early August and harvested from February to April, with its flavor at its best in winter and early spring.

Transplants

Young transplants matter more for cauliflower than for any other cole crop. Maryland sets out 5- to 7-week-old plants, Utah State sows 6 to 7 weeks ahead for a transplant with 4 to 6 mature leaves, and Iowa State sows only 4 to 5 weeks ahead. Larger, older or rootbound plants, and any shock at transplanting, push plants to form a button an inch or less across that never enlarges. Harden plants off for several days, water them in well, and plant them before they become rootbound.

Soil, spacing and feeding

Choose full sun and rich, well-drained soil that holds moisture. Clemson recommends a pH of 5.8 to 6.5, Iowa State 6 to 7. Plant 12 to 24 inches apart in rows 2 to 3 feet apart, and rotate cole crops so the same spot grows them only once every 3 or 4 years (Iowa State).

Cauliflower is a heavy feeder. Without a soil test, Clemson suggests 3 pounds of 5-10-10 per 100 square feet before planting, then a side-dressing 3 to 4 weeks after transplanting. Utah State uses ½ cup of 21-0-0 per 10 feet of row at about 4 weeks. Boron matters: Utah State and Wisconsin link a shortage to brown spots on the curd and a hollow, discolored stem, and Wisconsin notes that cauliflower needs more boron than broccoli or cabbage. Wisconsin adds that acid soil makes molybdenum unavailable, which causes narrow, strap-like leaves.

Water

Utah State recommends 1 to 2 inches of water a week, applied deeply, with mulch to hold moisture. Clemson names the first weeks after planting and the period as heads mature as the critical times. Drought during heading leads to loose, open heads and, according to Utah State, leaves growing up through the curd.

Blanching

White cauliflower turns yellow, cream or even purple in sun, and Utah State notes the color change comes with bitter flavors. When the head is about 2 inches across, pull three or four large outer leaves over it and fasten them with a rubber band or twine. Iowa State compares that size to a tennis ball, Utah State to a silver dollar, and UF/IFAS says 2 to 3 inches. In warm weather, Maryland advises tying loosely so air can circulate.

Self-blanching varieties grow their inner leaves over the head, though Wisconsin notes even these may need tying for full shade. Orange, green and purple varieties need no blanching.

Varieties by region

• Utah: Snow Crown, Amazing, White Contessa (heat tolerant), Self Blanche, and Denali for summer planting and fall harvest (Utah State).
• South Carolina: Amazing, Snow Crown and Milky Way (Clemson).
• Iowa: Aquarius (good heat tolerance), Fremont, Snow Crown, White Sails, Cheddar (orange), Graffiti (purple), and Vitaverde (green, best for fall) (Iowa State).
• Florida: Snowball strains, Snow Crown and Brocoverde (UF/IFAS).
• Lower Rio Grande Valley, Texas: Snow Crown and Snowball (Texas A&M AgriLife).
• Western Oregon and Washington, overwintering: All The Year Round, Fredor, Medaillon, Picasso and Prestige (PNW 548).

Pests and problems

The same caterpillars that attack broccoli (imported cabbageworms, cabbage loopers and diamondback moth larvae) chew leaves and hide in heads. Clemson stresses controlling them before heads form; Iowa State recommends Bt when caterpillars first appear. Flea beetles damage seedlings. Clemson lists hollow stem as the most common cauliflower problem, reduced by correct spacing and boron, and names black rot and head rot as the most serious diseases.

Harvest

Iowa State gives 50 to 60 days after transplanting for early varieties and 70 to 80 for late ones. Cut the head when it is firm, compact and smooth, before the curd starts to separate. Iowa State puts full size at 6 to 8 inches across, Penn State at 5 to 8; overmature heads turn grainy, or “ricey.” Leave a ring of leaves around the head to help it keep. Each plant gives one head. Refrigerated cold and humid, cauliflower keeps 2 to 4 weeks, according to Maryland and Iowa State.