Cauliflower (Brassica oleracea, Botrytis group) is one of the many cabbage-related cole crops that revel in cool weather. Mark Twain called it "a cabbage with a college education," but it's more than just a cabbage with airs. Cauliflower has a very distinct nuttiness and is similar to broccoli in flavor. The main edible part of both cauliflower and broccoli are the heads, formed from undeveloped flower buds.
Cauliflower is not the easiest vegetable to grow, because it is very sensitive to temperature changes. However, with a little TLC, it can be a very rewarding vegetable for your garden. You'll have many more variety options if you start your cauliflower from seed. All varieties, but especially white cauliflower, need to be blanched, by covering the head with its leaves. The purple varieties get their color from anthocyanin, an antioxidant. Unfortunately, both the color and the benefits disappear with cooking. Orange cauliflower is the result of a happy accident (a mutation). It gets its color from a relatively high content of beta-carotene.
Cauliflower has thick, oval leaves with pronounced mid-ribs and veins. The leaves and stem of cauliflower are both edible. The cauliflower head is composed of tightly packed undeveloped flower buds, often referred to as curds. The actual flowers of the cauliflower are the familiar 4 petals in a cross shape that give this family of vegetables the name cruciferous, which appears when the plant bolts.
Cauliflower plants like cool (but not cold) weather and are best planted in early spring (for an early summer harvest) or in midsummer (for a fall harvest). They have a moderately slow growth rate and are ready to harvest in two to three months from planting, depending on the type.
|Botanical Name||Brassica oleracea (Botrytis group)|
|Plant Type||Biennial, grown as an annual|
|Mature Size||12-30 in. tall, 12-24 in. wide|
|Sun Exposure||Full sun|
|Soil Type||Rich, well-draining|
|Soil pH||Neutral (6.5 to 7.5)|
|Bloom Time||Spring, fall|
|Flower Color||White, orange, purple, green|
|Hardiness Zones||2-11 (USDA)|
How to Plant Cauliflower
Start seeds indoors about four to six weeks before your average last frost date. Cauliflower doesn't like having it's roots disturbed, so biodegradable pots are recommended. Plant seeds about 1/2 inch deep, and keep the soil moist. They will sprout faster if they are kept warm, at 80 degrees Fahrenheit, so a heat mat is recommended.
Whether you are planting your own seedlings or some purchased from the store, be sure to harden off your transplants before setting them out in the garden. Space plants about 18 to 24 inches apart, with rows spaced 30 inches apart, to give the outer leaves plenty of room.
Cauliflower plants are biennial plants typically grown as annuals. However, if you want to save seeds, you will need to leave some plants unharvested, perhaps over the winter, with some protection from the cold.
Cauliflower plants need full sun, although a little partial afternoon shade in hot climates help prevent sun scorch.
Cauliflower needs a soil rich in organic matter, with a soil pH between 6.5 and 7.5. The soil should be well-draining, but cauliflower needs consistent moisture, to prevent buttoning (growth of very small flower heads in place of a single large head).
Cauliflower needs consistent moisture and plenty of it. Without sufficient water, the heads turn bitter. Provide at least 1 to 2 inches of water per week, and make sure it is soaking 6 to 8 inches into the soil. Leaving the soil dry in hot weather will cause the buds to open slightly, making the heads "ricey" rather than forming tight curds.
Temperature and Humidity
Cauliflower likes cool weather but is sensitive to frost. It begins to suffer in temperatures above 80 degrees Fahrenheit, which is why it's typically planted in spring or fall and harvested before or after the hottest days of summer. Mulch the plants at planting time, to keep the soil cool and help retain moisture.
Since cauliflower takes so long to mature, some supplemental feeding will be necessary. Feed every two to four weeks with an organic fertilizer, such as kelp or fish emulsion.
It seems plant breeders like to play with cauliflower because new varieties are always being introduced. Do some sleuthing at your local cooperative extension office to find varieties that do especially well in your area.
- Green Goddess F1: Lime green varieties with nice flavor and no blanching required; matures in 60 to 65 days
- Snow Crown F1: One of the easier-to-grow white varieties with some frost-tolerance and a short season; matures in 50 to 55 days
- Di Sicilia Violetta: Also called Violetta of Sicily or some other derivation; beautiful purple, Italian heirloom with a sweet, nutty flavor; matures in 70 to 80 days
- Cheddar F1: Pretty orange heads that are slow to bolt; matures in 55 to 60 days
Standard White vs. Colored Cauliflower
Orange cauliflowers have been bred from a genetic mutation that was discovered in 1970. The orange coloring come from beta-carotene, the same source of orange in carrots. It's not a GMO, just the result of a fluke mutation that has been used to make hybrid varieties. You might see it marketed as 'Cheddar' cauliflower, but it does not taste like cheese. It tastes like a sweet, nutty cauliflower.
Purple cauliflowers have been around for generations. There are several heirloom varieties, such as the popular 'Purple of Sicily', and some recent hybrids. They all get their purple color from the antioxidant anthocyanin, as does red cabbage, red grapes, and red wine. Unfortunately, most purple vegetables lose their color when cooked, and purple cauliflower is not an exception. Enjoy it raw for best benefits.
Another unusual variety in the Botrytis group is the alien-looking vegetable commonly known as Romanesco broccoli. It's probably a cross between cauliflower and broccoli, and it is not the easiest vegetable to grow. It's worth a try, though. The florets develop in a fractal pattern. Besides being beautiful, it has a wonderful nutty texture and flavor.
Cauliflower needs to be blanched to avoid discoloration, especially white varieties. The flavor isn't terribly altered if you allow it to turn its natural yellowish-brown, but it does seem to remain a little sweeter and a lot more appealing if blanched. Begin blanching the heads when they are about the size of a large egg. Start the process when the plants are fully dry, to prevent rotting. The traditional way to blanch is to fold some of the larger leaves over the head and tuck or secure them on the other side. You can hold them in place with a clothespin, rubber band or string. Don't fit the leaves too tightly; block the light but leave room for the head to expand. Once the leaves are in place, try not to get them wet and check under them periodically to make sure insects aren't using them as a hideout.
Most cauliflower varieties require about two months to mature, although some are a little quicker, and others can take up to three months. Since they will not form heads in warm weather and can handle only a light frost, be sure to choose a variety that will have enough time to mature in your climate. That means a fast-maturing variety if your spring or fall is short. Longer-maturing varieties are good choices for gardeners with mild or late winters. Gardeners in cold climates often have better luck putting out transplants in mid to late summer and harvesting in the fall.
Harvest when the heads reach the desired size and while the buds are still tight. Don't leave them too long, or the plants may bolt. It would be better to cut them when mature and freeze them for later use. Another option is to lift the whole plant and store it, roots, stem and all intact, in a cool, dry place.
Common Pests and Diseases
Unfortunately, cauliflower is susceptible to all the usual cole crop pests, and there are many, including cabbage maggots, cabbage loopers, and cabbage worms. Row covers offer good protection against cabbage moth butterflies, which lay eggs on the plants. Young transplants are also attractive to aphids and flea beetles, especially if grown in the spring. Groundhogs are exceptionally fond of cole crops. Fencing or caging is the best deterrence for the rodents.
Cole crops are also problem-prone when it come to diseases, with blackleg, black rot, and club root leading the pack. It's very important to not plant cole crops in the same place, year after year, and to clean up all debris at the end of the season, to prevent diseases overwintering in the soil.
Another common cauliflower problem is leaf tip dieback and distortion. This is generally caused by a lack of boron in the soil. Kelp or seaweed fertilizer should help prevent this.