General
Broccoli is a cool-season brassica grown for its compact green flower heads and tender side shoots. It thrives in cool, steady conditions with fertile, slightly alkaline soil. For the longest harvest, choose cultivars suited to your season (early/mid/late) and plan sequential sowings. After cutting the central head, many varieties produce multiple side shoots for extended picking. Keep growth steady with moisture, mulch, and regular light feeding. To reduce clubroot and pests, maintain pH ≥6.5, rotate crops 4–6 years, and use insect netting against cabbage butterflies.
Light
Full sun (6–8 h); tolerates partial shade in warm periods.
Soil type
Deep, fertile, moisture-retentive but well-drained loam or clay-loam enriched with compost; avoid waterlogging.
Water requirement
Consistent moisture: ~25–40 mm/week; never let the soil fully dry. Mulch to keep even moisture.
Nutrient requirement
High. Needs steady nitrogen; benefits from boron and molybdenum at adequate soil pH. Avoid fresh manure at planting.
Precultivation
Start seeds indoors 4–6 weeks before the last frost. Sow 0.5–1 cm deep in modules at 18–21°C; germination usually in 4–8 days. Once emerged, grow on bright and cool (12–16°C) to prevent legginess. Pot up if roots fill cells. Harden off 7–10 days before planting. For an autumn crop, a later sowing indoors in early summer also works, transplanting after the longest days.
Planting
Plant sturdy transplants when daytime temps reliably reach ~10°C and risk of hard frost is past. Spacing: 45–50 cm between plants, 50–60 cm between rows. Plant slightly deeper than in the tray, firm well, and water in. Incorporate well-rotted compost and, if soil is acidic (pH <6.5), lime several months ahead. Use fleece or insect netting immediately after planting to protect from flea beetles and cabbage white butterflies.
Pruning
No formal pruning. Remove yellowing or pest-damaged lower leaves. Harvest the central head while tight; this encourages numerous side shoots. Snip side shoots regularly to keep plants productive.
Maintenance
Keep soil evenly moist; mulch with straw, leaves, or compost. Feed lightly but regularly: side-dress with compost or a balanced organic fertilizer at planting and again midseason. Avoid overfeeding late with high N to reduce hollow stems. Net against cabbage butterflies and moths; check and hand-pick eggs/larvae. Use collars to deter cabbage root fly. Encourage beneficials with flowering companions. Maintain high hygiene—do not compost diseased brassica residues. In hot spells, provide afternoon shade and extra water to prevent buttoning (tiny heads).
Harvest
Harvest the main head when tight and domed, before florets loosen or show yellow. Cut with 10–15 cm of stem in the morning for best quality. Continue picking side shoots every few days; frequent harvest stimulates more shoots. Cool promptly after harvest. Fresh heads store 3–5 days refrigerated; blanched florets freeze well.
Common issues
Pests: cabbage white butterfly, diamondback moth, flea beetles, aphids, cabbage root fly—use fine mesh netting, sticky traps, and encourage beneficial insects. Diseases: clubroot (manage with pH ≥6.8, good drainage, long rotations, clean transplants), downy mildew (increase spacing, airflow), black rot (use clean seed, remove infected plants). Physiological: buttoning from stress (heat, drought, nutrient swings) and hollow stems from rapid growth—aim for steady conditions.
Rotation schedule
Rotate brassicas on a 4–6 year cycle, never following other brassicas. Ideal sequence: legumes → brassicas → fruiting crops → roots/leafy greens → back to legumes. Lime and add compost before the brassica year; avoid manuring immediately before susceptible root crops.
Pollination
Pollination not required for harvest (we eat immature flower heads). If saving seed, it is insect-pollinated and cross-pollinates with other Brassica oleracea.
Companion plants
Onion family, dill, chamomile, celery, lettuce, spinach, beets, marigold, nasturtium. Flowers that attract parasitic wasps are helpful.
Incompatible plants
Strawberries, pole/runner beans, tomatoes; avoid planting next to or after other brassicas due to shared pests and diseases.
