Cauliflower Seeds

How to Grow Cauliflower

The essential guide to growing Cauliflower (Brassica oleracea var. botrytis) from seed; with notes on germination, cultivation, harvest and even kitchen uses.

Seeds per gram: 300 – 350
Feed requirement: High, plus regular sidedressings during growth

Germination:

• Seed-starting: Sow indoors 4 – 6 weeks before planting out. Use modules or punnets; cover seed 5 mm deep.
• Temperature: 10 – 30 °C for best germination (7 – 14 days).
• Transplanting: Plant out when seedlings are 4 – 5 weeks old, hardened off and NOT root-bound. Older or pot-bound plants give poor heads.
• Direct sowing: Sow 3-6 seeds per spacing and once true leaves have emerged thin to the strongest seedling.

Cultivation:

• Soil & pH:
  • Rich, well-drained loam, pH 6.0 – 7.0.
  • Work in plenty of compost or aged manure.
• Spacing:
  • 45 – 60 cm between plants; 45-60 cm between rows.
  • Sow or transplant a mix of varieties to stagger harvest.
• Water & nutrients:
  • Keep beds evenly moist to avoid problem with head formation. 
  • Side-dress with a nitrogen-rich organic fertiliser 3 – 4 weeks after planting and again as heads start to form.
• Blanching:
  • When curds appear, fold or tie inner leaves over the head (or snap a few over) to keep them white and protect from frost or sunburn.
• Heat & frost protection:
  • Use shade cloth during heatwaves; row covers or frost cloth in very cold snaps.
• Trace elements:
  • Apply a brassica micronutrient mix if leaves are weak or curds deform—molybdenum and boron deficiencies both cause problems.

Problems & Pests:

• Slugs & snails:
  • Hand-pick or bait, especially in early sowings.
• Cabbage moth / cabbage white caterpillars:
  • Net plants or spray Bacillus thuringiensis (Dipel) every 7 – 10 days.
  • Try this land cress, as the brassica moths are attracted to it and it can be used as a 'trap' and certain catepillar species die when they eat the leaf.
• Hollow stems:
  • Caused by heat stress, excess nitrogen or boron deficiency—maintain steady growth and use balanced fertiliser.
• Poor curd formation:
  • Can result from warmth during heading, root-bound transplants or micronutrient deficiencies.

Harvest:

• Pick heads when curds are tight, firm and fully sized—before segments start to loosen and look “ricey.”
• Cut with 10–15 cm of stem and surrounding wrapper leaves for protection.
• Heads maturing in hot weather are lower quality; time sowings so most harvests occur in cool seasons.
• Store heads in the fridge (0 – 2 °C, high humidity) for up to two weeks, or blanch and freeze for longer keeping.

Follow these steps—rich soil, steady moisture, prompt harvest—and you’ll enjoy snow-white, flavour-packed cauliflower almost year-round.