Most cauliflower varieties require about 1.5-3 months of consistently cool weather to mature properly. Ideally, the daytime temperature while the cauliflower is maturing will be around 60ºF. This means that spring-planted cauliflower is difficult to grow in most climates without the aid of floating row covers to extend the season.
Cauliflower prefers fertile soil with a pH between 6.0 and 7.0. To increase the fertility of your soil, mix up to four inches of mature compost into your soil. If your soil is in particularly poor condition, also add a high-nitrogen organic fertilizer to enrich the soil. Organic fertilizers like alfalfa, cottonseed meal, and manure are good choices for planting cauliflower.
While cauliflower prefers full sun, it will tolerate some shade. Make sure you can provide at least 6 hours of direct sunlight.
Cauliflower does best when started inside and transplanted at about 4” high. This usually takes about 6-8 weeks. For a summer harvest, sow seeds 10-14 weeks before the last spring frost, planning on transplanting your seedlings into your garden beds about 4-6 weeks before the last spring frost. For a fall harvest, determine your first fall frost date and count backward 70 to 90 days (depending on variety) to figure out when you need to start your seeds. Floating row covers can extend your season on either end by several weeks.
Depending on variety, space your plants 18-24” apart in rows 36” apart.
Apply an organic mulch made of mature compost, leaves, or bark to keep weeds in check and soil temperature regulated.
Allow your plants between one and one and a half inches of water per week. cauliflower likes moist (but well-drained) soil. In particularly hot or dry conditions, increase the amount of water you feed your plants.
Use an organic, nitrogen-rich fertilizer when your cauliflower plants begin to form new leaves. Fish emulsion works well for fertilizing cauliflower. You can continue to fertilize the plants about once a week until they are ready for harvest.
Cauliflower plants have very shallow roots. If you disturb the soil you may accidentally break roots and damage your plants. If weeds develop around the plants, suffocate them with mulch instead of plucking them from the ground to avoid disturbing the roots.
As the cauliflower grows, a small "head" will begin to form at the center of its leaves (note that this is sometimes also called the "curd"). For ordinary white cauliflower, if this head is exposed to light while it is growing, it will yellow and darken. Though a darkened head of cauliflower is still edible, it is less visually appealing and will have a less-tender texture. Thus, it's important to use a process called "blanching" to keep the head pale and white. When the head is roughly the size of an egg, bend the plant's own leaves over the head so that it is shaded from sunlight.
If necessary, use twine or rubber bands to hold the leaves in place. Trapping moisture around the head can cause the plant to rot. Confirm the head is dry before blanching, and take care not to get any water on the head while it is bound. Don't bind leaves so tightly around the head that air cannot reach it. Note that non-white varieties of cauliflower (like purple, green, or orange cauliflower) do not need to be blanched. Additionally, some varieties of white cauliflower are bred to be "self-blanching", with leaves that naturally protect the head as it grows.