Cauliflower is among the many "cole crops" grown in the home vegetable garden. Cole crops is a general term used to describe several vegetables in the mustard family, including broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, and kohlrabi. All cole crops are cultivated varieties of the species Brassica oleracea. Cole crops are cool-season vegetables that grow best at temperatures between 60° and 70°F and can withstand light frosts without injury.
Suggested Cultivars | Planting | Care | Potential Problems | Harvest & Storage | More Information
Suggested Cultivars for Iowa
- Aquarius – mid-season; pure white heads; good heat tolerance
- Cheddar – mid-season; orange heads; poor heat tolerance
- Fremont – mid-season; white heads
- Graffiti – late season; purple heads; color turns bluish purple when cooked
- Snow Crown – early season; white heads; uniform and reliable
- Vitaverde – light green heads; best as fall crop
- White Sails – mid-season; white heads
Planting
Cauliflower is best started by seed indoors, and transplants are planted in the garden in early spring. A second crop can be planted in mid-summer for fall harvest.
Schedule
Plant cauliflower in the garden in mid-April in central Iowa. (Gardeners in southern Iowa can plant in early April, while those in northern counties should wait until late April.) Sow seeds indoors 4 to 5 weeks before planting outdoors or purchase young, stocky transplants at a greenhouse or garden center. Harden or acclimate the transplants outdoors for several days before planting. Initially place plants in a shady, protected location and then gradually expose them to longer periods of sunlight. Early-season cultivars mature approximately 50-60 days after planting. Late-season cultivars mature in 70-80 days. This means early cultivars can be ready for harvest as early as early June and late cultivars could be ready to harvest as late as mid to late July.
For a fall crop, plant transplants in the garden in early to mid July. Start transplants indoors 4 to 5 weeks before planting outdoors. Harvest can be expected from mid-September to mid-October, depending on when transplants were planted in the garden.
Site
Cole crops, like cauliflower, perform best in fertile, moist, well-drained soils. An ideal soil pH is between 6 and 7. The planting site should also receive at least 6 hours of direct sun each day. To avoid disease problems, rotate the placement of cole crops in the garden. If possible, plant cole crops in a given area only once every 3 or 4 years.
Spacing
When planting cole crops in the garden, space plants 18 to 24 inches apart within the row. Rows should be approximately 24 to 30 inches apart.
Care
Watering
Most cole crops, such as cauliflower, have shallow root systems and require weekly irrigation if rainfall doesn’t provide one inch of water per week. If possible use soaker hoses or drip irrigation systems to prevent wetting the foliage. Watering only the plant's root zone can also reduce the number of weeds that may germinate. Learn more about watering in this article: Watering Tips for the Garden, Lawn, and Landscape.
Fertilizing
If a soil test has not been done, apply 1-2 pounds of all-purpose garden fertilizer, such as 10-10-10, per 100 square feet, and incorporate it into the top 4-6 inches of soil before planting. Conduct a soil test to get more precise fertilizer recommendations based on your garden's fertility.
About 3-4 weeks after planting, broadcast a small amount of an all-purpose garden fertilizer in a band along one side of each row.
Mulching & Weeding
Control weeds to prevent competition for water, nutrients, and light. Shallow cultivation, hand pulling, and mulching are the best weed control options.
A 2-3 inch layer of mulch, such as straw, dry grass clippings, or shredded leaves, helps control weeds and conserves soil moisture. Learn more about weed control in this vegetable garden in this article: Weed Control in the Vegetable Garden.
Blanching
Cauliflower heads exposed to sunlight are usually cream-colored. If white heads are desired, the developing heads may need to be blanched. Blanching eliminates light penetration to the heads, keeping the heads white. When the heads are two inches across (about the size of a tennis ball), loosely tie the inner leaves over the heads with large rubber bands, cloth strips, or twine. The heads develop rapidly after tying and are generally ready to harvest within 1-2 weeks. Self-blanching cultivars don’t require tying as their inner leaves naturally grow over their heads.
Green, purple, or orange cultivars do not require blanching.
Potential Problems
Buttoning
Cauliflower plants exposed to stressful growing conditions may form heads prematurely. This development is called buttoning. Stressful conditions that may lead to buttoning include exposure to prolonged periods of temperatures below 50°F, dry conditions, and infertile soils. Also, large (older) rootbound transplants are more likely to button than young plants. Plants that button do not form usable heads.
Cabbageworms
Cabbageworms are greenish caterpillars that eat large, irregular holes in the foliage of most cole crops. Treat when caterpillars are first noticed with products containing Bacillus thuringiensis (Bt). When consumed by cabbageworms, this bacterium produces toxins which destroy the insects. Synthetic and other organic pesticides also can be used.
Flea Beetles
Flea beetles eat small, round holes in the foliage, resulting in “shothole” damage. Adults are tiny, shiny, black beetles. They possess large hind legs that enable them to jump.
Minor flea beetle damage will have little effect on crop yields. If significant damage begins to appear, treat plants with an insecticide. As always, carefully read and follow label directions when using pesticides.
No Crown or Head
Hot weather (86°F or more during the day and 77°F or more at night) can prevent cauliflower from forming heads or crowns. Avoid planting cauliflower too late in the spring. Earlier planting means they can mature and produce crowns before hot temperatures arrive. If temperatures cool down, plants may produce a crown.
Brownish or Cream-Colored Heads
White cultivars of cauliflower have to be blanched to maintain a white color. Blanching excludes sunlight to the heads, keeping the heads white. When the heads are two inches across (about the size of a tennis ball), loosely tie the inner leaves over the heads with large rubber bands, cloth strips, or twine. The heads develop rapidly after tying and are generally ready to harvest within 1-2 weeks. Some cultivars are self-blanching and have inner leaves that naturally grow over and shade the developing head.
Harvest & Storage
Early-season cauliflower cultivars mature approximately 50-60 days after planting. Late-season cultivars mature in 70-80 days.
Cauliflower should be harvested when the heads are smooth, firm, and compact. Full-sized heads may be 6 to 8 inches across. Over-mature heads will begin to open up and become “ricey.” Unlike broccoli which produces side shoots for additional harvests, each cauliflower plant produces only one head. Plants can be removed from the garden after harvest.
Cauliflower may be placed in perforated plastic bags and stored in the refrigerator for up to 2 to 4 weeks.
With good management practices, the average yield per 10-foot row of cauliflower is 8-12 pounds.
More Information
- Cole Crops (publication)
- Growing Broccoli in the Home Garden
- Growing Cabbage in the Home Garden
- Growing Brussels Sprouts in the Home Garden
- Growing Kohlrabi in the Home Garden
- Vegetable Harvest Guide
- Vegetable Planting and Harvesting Times
- Planting and Harvesting Times for Garden Vegetables (publication)
- Fall Planting of Vegetables
- Crop Rotation in the Vegetable Garden
- Weed Control in the Vegetable Garden