Cauliflower is a cool-season brassica grown for its edible curd, a dense mass of undeveloped floral tissue. It is the most temperature-sensitive of the common cole crops. Heat above 80°F during curd development causes looseness, browning, or a ricey texture. Consistent cool weather from transplant to harvest is the single most important factor in producing tight, white heads.
The crop is best started indoors and transplanted either in early spring (harvest before summer heat) or in midsummer (fall harvest as temperatures drop). White-curd varieties require blanching—gathering outer leaves over the developing curd and securing them—to prevent yellowing from sun exposure. Purple, orange, and green varieties skip this step. Soil pH of 6.0–7.0, high nitrogen, and 2–3 inches of mulch to stabilize moisture and soil temperature are important for uniform head formation. Crop rotation away from other brassicas for at least three years reduces clubroot and black rot pressure.
Cauliflower is high in vitamin C, folate, and glucosinolates including sulforaphane, a compound under ongoing clinical study for anti-inflammatory and cancer-preventive properties. Culinary uses span raw applications, roasting, steaming, and ricing as a low-carbohydrate grain substitute.
Clubroot
Swollen, distorted roots; wilting in midday heat; stunted growth and yellowing foliage. Plants recover poorly even with watering.
Remove and destroy infected plants with roots. Raise soil pH toward 7.2 with lime. Improve drainage and rotate out of brassicas for several years.
Black Rot
Yellow, V-shaped lesions spreading inward from leaf margins, with blackened veins. Severe cases cause wilting and leaf drop.
Remove and destroy infected plants. Use disease-free seed, rotate brassicas on a 3-year cycle, avoid overhead watering, and keep tools and beds clean.
Downy mildew
Yellowing on top of leaves with grey-purple fuzz underneath. Spreads rapidly in humid conditions.
Remove affected leaves. Improve air circulation. Avoid overhead watering. Copper spray as preventive.
Alternaria blight
Brown circular spots with yellow halos on leaves; spreads rapidly in wet weather.
Remove affected leaves immediately. Water at the base only. A copper-based fungicide can help if caught early.
White Rust
Raised white to cream-colored pustules on leaf undersides, with yellow blotches on upper surfaces. Infected tissue may swell or distort.
Remove and destroy infected leaves. Improve air circulation and avoid overhead watering. Rotate brassicas and avoid planting in previously infected soil.
Damping Off
Seedlings collapse at the soil line with thin, water-soaked stems; seeds may fail to emerge or rot before sprouting.
Sow in well-draining mix, avoid overwatering, and ensure good airflow. Remove affected seedlings and let the surface dry between waterings.
Sclerotinia Head Rot
Soft brown rot on the back of the flower head, white fungal growth, and hard black bodies inside; stems may wilt and collapse.
Remove and destroy infected heads and stems. Avoid overhead watering and crowding. Rotate away from sunflowers and other susceptible crops for several years.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Cabbage Worm
Pieris rapae →Ragged holes in leaves and green velvety caterpillars on undersides; dark green frass collects in leaf crevices and head.
Handpick caterpillars and eggs. Apply Bacillus thuringiensis (Bt) weekly during egg-laying. Use floating row cover to exclude white cabbage moths.
Cabbage Root Maggot
Delia radicum →Seedlings wilt suddenly despite adequate moisture. Roots show surface scarring and interior tunneling from small, creamy-white larvae feeding at and just below the soil line. Young transplants may collapse and die; older plants produce stunted, loose heads.
Apply floating row cover immediately after transplanting to prevent adult flies from laying eggs at the soil line. Drench soil with beneficial nematodes (Steinernema feltiae) before planting. Remove and dispose of infested plants and surrounding soil. Rotate all brassicas to a new bed each season.
Cabbage Looper
Trichoplusia ni →Ragged, irregular holes in outer and wrapper leaves caused by pale green caterpillars that arch their bodies in a looping motion when moving. Heavy populations consume leaf tissue down to the midrib and bore into forming heads.
Apply Bacillus thuringiensis var. kurstaki (Bt) at the first sign of feeding, targeting larvae while they are small. Reapply every 5–7 days during wet weather. Use floating row cover to exclude egg-laying adults. Hand-pick caterpillars on small plantings. Parasitic wasps are effective natural controls; avoid broad-spectrum insecticides that kill them.
Aphids
Aphididae →Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.
Flea Beetle
Alticini →Small round shot-holes scattered across leaves; tiny dark beetles that jump when disturbed. Heavy feeding stunts young plants.
Use floating row covers on seedlings. Remove crop debris and weeds that harbor beetles. Apply kaolin clay or spinosad if damage is severe.