Cauliflower - Brassica oleracea
To keep cauliflower heads white, or to "blanch" them, you can tie up leaves (shown left), keep in mind however that tying the leaves into a vertical position tends to trap rainwater, which can bead on the head and sometimes rot it. You are better off simply bending four or five of the large, outside leaves over the crown, then tucking the leaf tip into the opposite side, or use "self-blanching cultivars (shown right) that grow their own "shading" leaves.
Zones 3 and warmer
Grow as spring and fall crops in cool-spring clmiates, and as a winter vegetable in mild climates
Climate Zones Maps
Full sun, partial shade will reduce head size
Needs soil rich in organic matter, well-drained, with plenty of calcium; Ideal pH 6.0 to 6.8, but can tolerate pH as high as 7.4
Needs steady, even moisture
Set plants 18 to 24 inches (45 to 60 cm) apart; 2 to 3 feet (.61 to 1 m) between rows
Pick cauliflower when the heads are full, but before the curds begin to separate
Comments: You can choose from white, purple and green-headed cauliflower. Purple cauliflower tastes more like broccoli and turns green when cooked. Most white-headed cultivars need to be protected from the sun to produce their snowy white curds; a few cultivars are self-blanching.
Planting Site: Cauliflower grows best in full sun, any partial shade will reduce head size. As with all brassicas, careful rotations are important to prevent pest and disease problems. Avoid planting cauliflower, or any related cabbage-family crops (Brussels sprouts, kale, cabbage, and broccoli), where brassicas have grown in the last three years.
Planting & Growing Guidelines: If you've had problems with cauliflower in the past, look for cultivars that are tolerant to problems such as high temperatures, hollow stem, and purple tinge. For spring crops, start plants indoors ten weeks before the last expected frost. Set out transplants four to five weeks before the last expected frost when the soil temperature is at least 50° F (10° C). Young plants will withstand a light frost and mature plants can tolerate a moderate frost, but a severe frost may cause the plant to form a "button" instead of a full-sized head. Start fall crops 90 to 120 days before fall frost (Example: plant in August for an October-November harvest). Set out seedlings or direct-seed. In mild winter climates, you can grow your cauliflower for a winter or spring harvest. Cauliflower requires a steady supply of moisture. Mulching helps preserve moisture and keep the soil cooler.
Unless you've chosen self-blanching cultivars, or purple and green cauliflower cultivars that do not need blanching before harvest, you will need to blanch your cauliflowers to get those pure, white curds. Wait until the head reaches about 2 inches (5 cm) in diameter and starts pushing through the inward-curving leaves that cover it. You can then tie the outer leaves loosely over the head, or better, simply bend four or five of the large, outside leaves over the crown, then tuck the leaf tip into the opposite side. If the leaves partially snap while bending, that's OK. Bend a few more leaves over the following week if the head needs more coverage as it expands. The head will reach harvestable size 2 to 14 days, depending upon the temperature, because cool weather may slow head development.
More than any other vegetable, cauliflower is very sensitive to weather conditions. Heat can cause browning of the curds or stem rot. Dry spells or extremes of cold or heat can cause bolting (premature flowering), buttoning (formation of small, undersized heads), or ricy curds (separation of heads into small rice-like sections). Extreme fluctuations in temperature can cause leaves to grow among the curds. If you live in an area with extreme weather fluctuations, it's a good idea to start a few cauliflower plants every week, for 4 to 6 weeks, to see if some will get the right weather conditions.
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Fertilizer: Lightly broadcast some 10-10-10 over the area, till in, and then plant transplants or sow seeds. When the plants start to head, side-dress with 1 tablespoon (15 ml) per plant of 5-10-10, or one large handful of good compost which generally equals the same. Sprinkle around the base of the plant, but not up against the stem, and water in.
Pest and Disease Prevention: At planting time, protect transplants with cutworm collars. Brown or discolored curds can be a sign of sunburn, but are also a sign of boron deficiency. Insufficient phosphorous can cause some white heads to become tinged with purple, and you'll need to test your soil and perhaps add a superphosphate fertilizer the following year. Control cabbageworms with row covers or spray or dust BT (Bacillus thruingiensis). To avoid soilborne diseases, don't plant cauliflower, or any related cabbage-family crops (Brussels sprouts, kale, cabbage, and broccoli), where brassicas have grown in the last three years.
Helpful Articles: Cutworm
Proper Use Of Insecticidal Soap
Heavyweight Row Covers
Common Problems: In humid climates, heads may discolor during blanching due to excess moisture. Clip leaves together loosely to shade the head without cutting off the air circulation.
Days to Maturity: Heads are ready 50 to 125 days from transplanting.
Harvest and Storage: Pick cauliflower when the heads are full, but before the curds begin to separate. Cut through the stem under the head, leaving a few "wrapper" leaves for protection. Curds bruise easily, so handle with care. Before eating or storing cauliflower, soak it in lightly salted water, (1 to 2 tablespoons (15 to 30 ml) of salt per gallon (4 l)), for 30 minutes to drive out any unnoticed cabbageworms that may be hiding in the heads. Cauliflower will keep for one to two weeks in the refrigerator if wrapped in plastic. It does not store well in a root cellar. The best way to store it for longer periods of time is to freeze it.
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