Cauliflower is grown essentially the same way as broccoli, but it is much more sensitive to variations in growing conditions, and more prone to failure if stressed. Transplants should be started six to eight weeks before last frost, and not be exposed to temperatures below 50F/10C; I grow them right in with my tomato transplants.
Many people buy started cauliflower plants because of their delicacy, but unless you know the grower and can trust his or her methods, this is unwise. Most commercial growers of bedding plants have a hard time giving plants the precise care that cauliflower requires, and unless you inspect the plants carefully before buying you may be disappointed at harvest time.
Obviously the plants should be free of insects and disease. But look at their general condition, too. The stems should be green, less than a pencil thickness in diameter, the leaves soft and satiny, and the plant’s roots should not have started circling the edges of the container. Ideally, look for a tag in the flat that has the planting date; if it was more than a month previous, pass by those plants.
At one time we had only white cauliflower, but now there are orange and purple varieties as well, though some of these more resemble broccoli than cauliflower.
Cauliflower plants should not be set out until the weather can be counted on to stay above 50F/10C in the daytime. Light frosts won’t hurt them, but extended periods of cool weather will lead to buttoning—the formation of tiny, bitter heads on otherwise normal plants. Extended high temperatures can lead to other disorders, such as “ricing.”
It is necessary for all the members of the cabbage family, but especially cauliflower, to be grown quickly, without interference from low temperatures, lack of moisture or fertility, or any kind of insect damage. To minimize transplant shock, we water-in our newly set cauliflower plants with a fish fertilizer solution (at one tablespoon per gallon of water) and then cover them immediately with a floating row cover.
Spacing for cauliflower is equally important. The plants should have a minimum of eighteen inches square, and twenty-four inches square is better. You cannot manipulate them for different results as you can with broccoli. If grown in rows, allow a full three feet between the rows; in beds we run a single row down the center, just like Brussels sprouts. You can grow cauliflower eighteen inches equidistant in beds; but be prepared to pamper the plants and keep a close eye out for any nutrient or water deficiency. Purpling or paling of the leaves means they are getting hungry and should be fed immediately with a fish fertilizer mix like they had at transplant time.
Cauliflower should be blanched before harvest, beginning when the curd (the partially developed, edible flower head) is about the size of an egg. You can do it one of three ways: tie the leaves up over the curd with twine as my grandfather did, fasten them with a rubber band as I do, or break the midribs of the leaves just above the level of the curd and layer the leaves over the curd to block the sunlight.
Un-blanched cauliflower curds turn a pale purplish yellow or tan color, and are not as tender as when properly grown. Harvest promptly just before the curds begin to separate.