CULTURE: Cauliflower prefers a well-drained, fertile soil high in organic matter, a pH of 6.0–7.5 with consistent moisture throughout the growing season. Irrigate regularly for best results. Cauliflower does not do well in hot weather; the best success is with spring and fall crops.
EARLY SPRING CROP: Use early and midseason varieties. Sow in 72-cell plug flats. Seedlings should be ready to transplant in 4–6 weeks. If possible, keep soil at least 70°F (21°C) until germination, and 60°F (16°C) thereafter. Transplant outdoors when seedlings are no older than 4–5 weeks old. Older plants tend to be stressed and do not perform as well as actively growing seedlings. Harden plants carefully by gradually increasing cold before transplanting out, 18″ between plants and 24–36″ between rows.
FALL CROP: Use midseason and storage varieties. Start seedlings as above in May and transplant to the garden in June–July. To ensure mature heads, seed the crop early in areas where heavy freezes occur early in fall.
WINTER CROP: Successful cauliflower crops can be grown where winters are mild (temperatures rarely below 32°F (0°C)). Transplants can be set out from September to February in these regions.
DIRECT SEEDING: Sow 3–4 seeds 18″ apart, ½” deep, rows 24–36″ apart, thinning to one plant in each group.
DISEASES: Adhere strictly to a preventive program including (1) long crop rotations with non-cruciferous crops, (2) clean starting mixes and outdoor seedbeds, and (3) strict sanitation practices. Black rot can be seed-borne. We only stock seed lots that have been tested free of black rot in a sample of 30,000 seeds. For seed lots received after August 2015, individual seed lots have been tested free of blackleg in a sample of 1,000 seeds.
NOTE: A disease-free test result means that in the sample tested, the pathogen targeted was not found. It does not guarantee a seed lot to be disease-free. However, no method of seed treatment can positively ensure freedom from disease. We are glad to help with specific questions.
INSECT PESTS: Repel flea beetles and root maggots on young seedlings by covering with floating row covers from the day of planting. Treat flea beetles with pyrethrin or azadirachtin if heavy pressure is observed. For cabbage worms and loopers, use Bacillus thuringiensis (Bt.). Cutworm prevention: Cultivate soil 2–4 weeks before planting to work in cover crops and destroy weeds.
BLANCHING: When small whiteheads become visible through leaves, gather the outer leaves over the head and tie with string or a large rubber band to preserve white curd colour. Although tying is not necessary to grow cauliflower, the practice helps prevent yellowing of the curd due to exposure to sunlight and results in better head quality when curd develops during hot weather.
HARVEST: Keep an eye on development, cutting heads when the desired size is obtained but before the curds become loose, or “ricey.”