Cauliflower is a member of the cabbage family or colecrops. All members of the family prefer cool weather and cauliflower is no exception. The plants will not head properly in hot weather. Thus, it should be grown as a spring or fall crop with the best quality production occurring in the fall.
Transplant in mid April for a spring crop, early July for a fall crop. For spring production, start transplants 5 to 7 weeks prior to planting date. For fall, seed in a bed, 10 to 12 seeds per foot of row, 1/4 to 1/2 inch deep in rows 12 inches apart. Seed sown about July 4 will produce transplants by August 1. Keep the seed bed moist by adequate irrigation. Plants should be carefully lifted, sorted for uniform size, and reset in the field.
There are several good herbicides that can be used for weed control. Obtain a copy of FG-600, titled: Midwest Vegetable Production Guide for Commercial Growers, from your local county extension office or Ag Publications and Distribution, Printing Bldg., Iowa State University, Ames, IA 50011.
Rows should be spaced 2 1/2 to 3 feet apart, 15 to 24 inches between plants in-row depending on the variety.
At transplanting apply 0.5 pint (8 oz.) of starter solution per plant. Special fertilizer grades are used at a rate of 3 pounds per 50 gallons of water. Examples are 14-28-14, 10-52-10, and 23-21-17. The high phosphorus liquid 10-34-0 can also be used at the rate of 2 quarts per 50 gallons of water. For small quantities, use 2 tbs. of any complete fertilizer analysis such as 12-12-12 per gallon of water.
The soil pH should be between 6.0 and 6.5. In the western part of the state, the soil pH may approach 8.0, reducing zinc(Zn) and boron (B) availability. Also, in eastern Iowa, especially along the Mississippi river, the low organic matter, acidic, sandy soils may be low in B. Cauliflower is a high user of B. Therefore, it is recommended that 1 to 2 lbs/acre of B (10 to 20 lbs/acre of borax or solubor) be applied before planting. Do not add too much as rotational B-sensitive crops, such as corn, peas, or beans will be injured.
Phosphate (P2O5) and potash (K2O) should be applied according to soil test results. However, a maintenance application might be 50 lbs/acre of P2O5 and 100 lbs of K2O per acre.
Nitrogen (N) recommendation depends on soil type and organic matter content. On sandy loams apply 100 lbs/acre just prior to planting and another 60 lbs as a sidedress application 3 weeks after transplanting. If heavy rain occurs on sandy soils, apply an additional 30 lbs N as a sidedress. On silt loam soils or heavier with >3% organic matter, apply 80 lbs N/acre as 2/3 pre-plant and 1/3 sidedressed 30 days after transplanting.
Andes, op - main season, forming heads need to be blanched
Self-blanche, op - late season, does not need tying if plants fertilized properly
Snow Crown, F1 - early season, reliable for spring and fall production
White Empress, F1- main season
Silver Streak - late season, for fall harvest
"BUTTON" HEADS. Poor growing plants may produce only very small heads or "buttons." This may be induced by cold weather (below 50F), drought or poor fertility. Old transplants may also perform poorly.
BLANCHING. When the head becomes 2 inches in diameter, gather the outer or longest leaves over the head, and tie them together with twine, nylon strips, or colored rubber bands. The blanching procedure produces white, tender heads. Heads exposed to sunlight become cream colored and somewhat coarse, and they develop an undesirable flavoer. The self-blanching types have not performed well in Iowa.
For weed, insect and disease control obtain a copy of FG 600, titled: Midwest Vegetable Production Guide for Commercial Growers, from your local county extension office or Ag Publications and Distribution, Printing Bldg., Iowa State University, Ames, IA 50011.
Common problems in Iowa have been:
Insects = cabbage worms, cabbage loopers, and aphids
Diseases = Alternaria leaf spot, black leg, black rot, and downy mildew
Harvest the heads when compact, smooth, and clear white before the heads begin to separate and become "ricy." Full-sized heads may be 6 to 8 inches across. Cut with 1 or 2 whorls of leaves to protect the head. It is better to cut a little early than risk losing the head to over maturity. In warm weather heads may develop in as little as 3 to 5 days after tying, but with cooler temperatures head development could take as long as 2 weeks. Trim heads and cool immediately.
10 pounds per 10 foot row or 5 tons/acre.
Store heads at 32F, 90-95% relative humidity for up to 2 to 4 weeks.
Hydrocooling or forced-air cooling is necessary in hot weather.
............Justice for All
The Iowa Cooperative Extension Service's programs and policies are consistent with pertinent federal and state laws and regulations on nondiscrimination regarding race, color, national origin, religion, sex, age, and handicap.
Cooperative Extension Service, Iowa State University of Science and Technology and the United States Department of Agriculture cooperating. Stanley R. Johnson, director, Ames, Iowa. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.