Cauliflower is broccoli’s cousin, and while growing conditions are similar to broccoli, cauliflower is a sensitive soul. Cauliflower doesn’t like things too hot, too cold, or too dry, and can be quite persnickety when all its needs are not met. However, with a little perseverance and tender loving care, you can master this temperamental vegetable.
The pH of the soil should ideally range from 6.5 to 7.0. This will discourage clubroot disease. Amend your soil with two inches of compost worked into the dirt. Cauliflower likes very fertile well-drained loamy soils. If your soil is very sandy or composed of a lot of clay, add organic matter to it. Cauliflower needs rich soil with plenty of nutrients and a steady supply of water. You can also prepare your cauliflower bed the previous season by planting a green manure crop and turning it under.
You can also apply Protogrow® at planting, after the plants begin to develop, and once they start forming heads to ensure an adequate nutrient supply.
When to Plant
Cauliflower prefers cool temperatures, which is why three-quarters of the cauliflower grown in the United States is done so in the California coastal valleys. The key to successful harvesting of this vegetable is getting your timing just right in catching perfect temperatures. You want consistent temperatures between the 65 degree F and 80 degree F range.
In the North, plant cauliflower for a fall harvest. You’ll set out transplants about 60 to 90 days before the first fall frost. In zones 7 and 8, you can plant in early spring and again in late summer (but don’t set out your seedlings more than three weeks before the last spring frost date). You can grow cauliflower in zones 8b and above as a winter crop.
How to Plant
Start your seedlings indoors, about six weeks before you intend to transfer them to the garden. The seeds germinate best in 80 degree F temperatures. Begin to harden them off when the seedlings reach about 5 to 6 weeks of age. Cauliflower needs 6 full hours of sun a day.
Space your transplants from 18 to 24 inches apart, with rows at minimum 30 inches apart. Make sure they are firmly planted into the soil. Your plants need a steady and even moisture supply to thrive. The use of organic mulch will help retain moisture in the soil as well as keep down weeds. If no rainfall occurs, make sure the plants receive about 1 to 1 1/2 inches of water a week.
After the first month in a spring or fall-planted crop, you can water in Protogrow® every two to three weeks. A winter crop needs to develop more slowly, so your plants don’t require this extra boost.
Your flower heads need to be protected from the sun to retain their white color. The process of folding the outer leaves over the cauliflower head is called blanching. When the heads are about 2 inches wide, pull the outer leaves up and over the head, fastening them together with a clothespin, twine, tape or rubber bands. Even self-blanching varieties may require this step if sun scorch is a possibility.
About one to two weeks after you tie up the leaves, your cauliflower should be ready for harvesting. As long as the head remains compact, you can leave the head to grow. If it begins to open up, however, no matter what size it is, harvest it. The quality will only decline the longer you leave it there. When the head is 6 to 8 inches in diameter, cut the stem below the head.
Remember, your cauliflower will not withstand temperatures lower than 25 degrees F, so harvest them no matter what size they are to avoid losing your whole crop if temperatures are predicted to drop to those lows.
Too much heat, cold, or sun scorch can have a detrimental effect on your plants. You have to achieve the right balance between leaf growth and head growth. Stress will cause the plant to sprout a head prematurely (called buttoning) and you’ll be left with tiny button-size heads.
If your cauliflower curds separate and the heads are leafy, the temperatures were too high. Try planting for a fall crop the next time, or an overwintered one if you live in the South.
Some of the possible pests that can be harmful to your plants are caterpillars, which include cabbage worms, cabbage loopers, cutworms, army worms, and flea beetles. Place tinfoil collars around the stems of your plants at soil level. Apply a Bt solution to the plant every 7 to 10 days, and of course, hand pick off those that you see.
Cabbage root maggots are the larvae of flies and are the size of a grain of rice which feed on the roots. To keep them from hatching, firm the soil well around each seedling. Applying a tinfoil shield at the base of the stem and then covering with mulch will prevent the adult flies from laying eggs in the soil.
The clubroot fungus causes wilted, discolored leaves and the roots are a gnarly mess. Most clubroot fungus is brought in from purchased transplants, so growing your own seedlings should help avoid this. If you find plants with the fungus, pull them out and destroy them. There’s nothing that can be done or any corrective measures taken to save the plant. Avoid planting any brassicas in the affected section of the garden for at least 4 years. Clubroot prefers acidic conditions, so adding lime to acidic soil at least two months before planting can help prevent the fungus.
Damp, hot conditions can cause a host of problems, including downy mildew, powdery mildew, grey mold, and bacterial soft rot. Insure your plants have adequate spacing with plenty of air circulation. Avoid watering your plants in the evening and don’t soak the plant itself. Instead, water around the perimeter of each plant.
If your curds turn brown, it can be from sunburn or from downy mildrew, a fungal disease. Either way, the head is inedible and you’ll need to destroy the plant to prevent any chance of spreading a possible disease.