Once the summer heat kicks into high gear, it can be challenging to start new plants in the garden. You might have limited garden space after your spring plantings; some seedlings will wither under scorching temperatures, and other crops will be killed by the autumn frost if they are started too late.

Cauliflower can withstand a summer planting and flourish as temperatures cool down, making it an excellent choice to start in midsummer. However, the plant is also quite fickle, making it difficult to grow successfully.

A cole crop related to vegetables like broccoli and cabbage, cauliflower produce heads of tightly packed edible flower buds. Marie Iannotti, writing for the home design site The Spruce, says the leaves and the stem of cauliflower are edible as well. While white cauliflower is the most common variety, the vegetable also comes in colors such as orange and purple.

Preparation

Maintaining a constant temperature is the key difficulty in growing cauliflower. The Old Farmer's Almanac says it requires consistently cool temperatures, ideally in the 60-degree range. If temperatures get too warm, cauliflower may "button," or prematurely form undersized heads.

Some varieties can grow quickly enough to be planted in the spring and harvested before temperatures heat up too much in the summer. However, the University of Minnesota Extension says most types of cauliflower are best planted in July. The warmer temperatures will help support foliage growth, but cooler late season temperatures are better for the flower heads.

You can start your seeds indoors a few weeks before this time, or direct seed in the garden. The Old Farmer's Almanac says you'll likely have better luck growing from transplants instead of seeds.

Choose a site receiving at least six hours of sunlight per day. However, Iannotti says a partially shaded site can also work well, since it will reduce the possibility of buttoning on hot days.

Soil quality is very important. The gardening company Bonnie Plants recommends testing your soil to determine the pH level and modifying it to 6.5 to 6.8. The soil should also be moist, well-draining, and modified with compost or other organic matter.

Plants should be spaced about 18 inches apart, with about 30 inches between rows. If using seeds, the University of Minnesota Extension recommends planting a few seeds no more than a half-inch deep. After seedlings emerge, thin them so only the strongest one of each group remains.

Care

The soil should be kept consistently moist to encourage growth. The Old Farmer's Almanac says cauliflower benefits from two inches of water per week, which usually requires supplemental watering at least once a week.

Nitrogen-rich fertilizer can further support robust growth. Bonnie Plants says you can regularly feed the plants or add a fertilizer that continuously releases helpful materials.

If you are planting a variety that can be set out in spring, it's best to start as soon as possible. Fabric row covers or even old milk jugs can be used to shield the seedlings from chilly temperatures until the last frost passes.

Once the cauliflower heads are about two inches wide, tie the outer leaves over the head with twine or a rubber band. This "blanching" process helps preserve the white color of the cauliflower. The University of Minnesota Extension says some varieties are self-blanching and won't need to be tied; more colorful varieties also don't need to be blanched.

Cauliflower is susceptible to several pests, including cabbageworms, flea beetles, and root maggots. Row covers can help deter these insects.

Diseases like black rot and club root can also affect the plant. The best way to avoid these problems is to practice crop rotation. Avoid planting cauliflower or related plants in any location where cole crops have grown in the past four years, since disease spores lingering in the soil can affect any new plants as well.

A shortage of boron in the soil can lead to issues such as leaf tip dieback. Iannotti says kelp or seaweed fertilizer is helpful for preventing these problems.

Harvesting

Cauliflower is typically ready to harvest about seven to 12 days after the blanching process. The Old Farmer's Almanac says the heads should be compact and firm, ideally with a diameter of six to eight inches.

Bonnie Plants says you can allow the plant to grow as long as it remains compact. Untying the leaves to do a quick check on the head is possible, and the leaves can be tied back again after this inspection.

The flower heads might start to open up when they have a smaller size. It's best to harvest them at this time, since they won't grow larger and will decline in quality if you leave them alone.

Cauliflower will develop a loose, course appearance if left in the ground for too long. These plants will not have a good taste and should be discarded.

To harvest cauliflower, use a knife to cut away the head. The University of Minnesota Extension says you should sever it at ground level, then remove the leaves tied over the head.

Harvested cauliflower can last up to three weeks in cold, moist conditions, but should be consumed within a week of being refrigerated. For longer term storage, it can be frozen or pickled.