Cauliflower is a cool-season crop in the cole family (Brassica oleracea), which includes broccoli, Brussels sprouts, cauliflower, collards, kale, and kohlrabi. However, it is more temperamental than its relatives. The trick to growing cauliflower is consistently cool temperatures, which is why almost three fourths of commercial cauliflower is grown in the coastal valleys of California. However, you can try growing it at home no matter where you live, but timing is important to catch the temperature just right. It also needs rich soil and a steady supply of water and nutrients. Cauliflower likes temperatures in the 60s. In young cauliflower plants there is a fine balance between leaf and head growth. Any stress tips the balance toward premature heading, or “buttoning,” when the plant makes tiny button-sized heads. This can happen when it’s too hot or too cold. This also happens if plants sit in packs too long, or are stunted by drought or poor soil. Now that you know the challenges, allow us to equip you for success.
Soil, Planting, and Care
Like most vegetables, cauliflower needs at least 6 hours of full sun each day; more is better. It also needs fertile, well-drained, moist soil with plenty of rich organic matter. The soil pH should be between 6.5 and 6.8 for optimum growth and to discourage clubroot disease. To be sure of soil pH, test the soil. You can buy a kit, or get a soil test through your regional Cooperative Extension office. Apply fertilizer and lime according to test recommendations. Add nitrogen-rich amendments such as blood meal, cottonseed meal, or composted manure to the soil or work a timed-release vegetable food such as 14-14-14 into the soil thoroughly before planting. For a boost, use Miracle-Gro® Shake ‘N Feed® Tomato, Fruits & Vegetables Plant Food at planting and again after plants begin to develop new leaves and again when they start forming heads.
Set out spring plants early enough that they can mature before the heat of summer, but not so early that they freeze; 2 to 4 weeks before the last frost is about right. Be prepared to protect them from cold weather with a cover. You can use fabric row covers or homemade items such as old milk jugs.
Set out fall crops about 6 to 8 weeks before the first frost. Be prepared to shade them, if needed, to protect from heat.
Space cauliflower plants about 18 inches apart in the row with 30 inches between rows to allow room for walking. Remember, plants need an even moisture supply to avoid stress. Organic mulch will help keep the soil cool and moist and will suppress weeds. Apply 1 to 1.5 inches of water per week if rain falls short.
When the cauliflower heads are about 2 inches wide, you may need to pull the leaves up over each little head and fasten with a clothespin or twine. This shades the head to ensure it will be white and tender at harvest (called blanching). Plants are supposed to “self-blanch,” in which the leaves naturally curl over the head, but watch them because they often need the help of a clothespin.
Besides avoiding stresses, watch for cabbage loopers, imported cabbageworms, cabbage root maggots, aphids, and flea beetles. Possible disease pests include black leg, black rot, clubroot, and yellows. Contact your regional Cooperative Extension office for more information on pest identification and current control recommendations. The best way to minimize problems is to keep your plants healthy and your garden clean.
Harvest and Storage
The head is usually ready about a week or so after you tie up the leaves. Leave the head to grow as long as it stays compact (ideally, it will grow to 6 to 8 inches in diameter). You can untie it to peek and tie it back if needed. If the head begins to open up, cut it from the plant at the base of the neck no matter how small it is because it will only decline in quality. The head should keep in the refrigerator for at least 2 weeks.
When is the best season to grow cauliflower?
It depends on the area. Cauliflower does not grow well in hot or in severe cold temperatures. Grow in fall, after the temperature is below 75 degrees F, and in winter in locations where the temperature does not fall below 25 degrees.
What does "blanching" mean, and how is it done?
Blanching is the process done to protect the cauliflower head from sunlight. It is done by pulling the outer leaves up over the head of the cauliflower and tying the leaves with a rubber band or soft twine.
Why do my cauliflower plants have small heads?
Cauliflower needs fertile soil that is rich in organic matter in order to hold moisture that will encourage uninterrupted growth; this will prevent heads from forming prematurely.