How to Take Care of Broccoli Plants

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Broccoli field

Broccoli (Brassica oleracea var. italica) is a nutritious cool-season crop that requires specific care to produce quality heads. This guide covers essential practices for both home gardeners and commercial growers.

How to Take Care of Broccoli Plants

Growing Requirements

Climate and Temperature

Broccoli thrives in cool weather with optimal temperatures between 60 and 70°F (15-21°C). Plant in spring (2-4 weeks before last frost) or fall (85-100 days before first frost). Fall crops generally produce better quality heads due to cooler temperatures. The plant can tolerate light frosts down to 26°F (-3°C), and frost actually improves flavor. However, temperatures above 75°F cause premature bolting and poor head quality.

Soil Preparation

pH and Type: Broccoli requires well-drained soil with pH 6.0-7.0 (6.5 is ideal). Loamy soil with 3-5% organic matter works best.

Home Gardens (per 100 sq ft):

  • Add 2-4 inches compost (50-100 lbs) 2-4 weeks before planting
  • Mix in 2-3 lbs of 10-10-10 fertilizer
  • Add 3-5 lbs bone meal and 2-3 lbs blood meal
  • Adjust pH: Add 5 lbs lime to raise pH by 0.5-1.0, or 1-2 lbs sulfur to lower it

Commercial Fields (per acre):

  • Apply 10-20 tons compost or well-aged manure
  • Broadcast 800-1,000 lbs of 10-10-10 fertilizer
  • Alternative: 175-260 lbs urea (46-0-0), 175-260 lbs triple superphosphate (0-46-0), and 200-300 lbs potassium chloride (0-0-60)
  • Adjust pH with 1-4 tons lime per acre based on soil test

Planting

Spacing:

  • Home gardens: 18-24 inches between plants, 24-36 inches between rows
  • Commercial fields: 14-18 inches in-row, 36-40 inches between rows (14,000-18,000 plants per acre)

Transplanting: Use 4-6-week-old seedlings with 4-6 true leaves. Plant at the same depth as containers. Water immediately with 1-2 cups per plant (home) or 0.5-1 inch per acre (field).

Irrigation Management

Water Requirements by Growth Stage

Establishment (0-2 weeks):

  • Home gardens: 1-2 cups daily per plant
  • Commercial: 0.1-0.2 inches daily
  • Keep soil consistently moist

Vegetative Growth (3-8 weeks):

  • Home gardens: 1-1.5 inches per week, watering 2-3 times weekly
  • Commercial: 0.3-0.5 inches every 2-4 days
  • Water depth: 6-8 inches

Head Formation (8-12 weeks):

  • Home gardens: 1.5-2 inches per week, every 2-3 days
  • Commercial: 0.3-0.5 inches every 1-3 days
  • Never allow soil to dry completely during this critical stage

Irrigation Methods

Home Gardens: Drip irrigation is best (90-95% efficiency). Run 1-2 hours per irrigation. Soaker hoses are a good alternative. Avoid overhead watering, which promotes disease.

Commercial Fields: Drip/trickle systems provide the highest efficiency (90-95%) and allow fertigation. Install drip tape with emitters every 8-12 inches, with a flow rate of 0.3-0.5 gallons per hour. Furrow irrigation is less efficient (50-70%) but works on sloped fields.

Fertilization

Broccoli is a heavy feeder, requiring 150-200 lbs of nitrogen per acre for commercial production.

Home Garden Schedule

At Planting: Mix 1 tablespoon of 10-10-10 plus 2 tablespoons of bone meal into each planting hole.

Week 3: Side-dress with 1/4 cup (60 ml) blood meal per plant OR 1/2 cup (120 ml) ammonium sulfate per 10 feet of row. Water with 2-3 cups per plant immediately after.

Week 6: Apply liquid fertilizer every 2 weeks until harvest. Use fish emulsion (2-4 tablespoons per gallon, apply 1 cup per plant) OR water-soluble 20-20-20 (1 tablespoon per gallon, 1 cup per plant).

Weeks 9-10: Continue feeding but reduce concentration by 25% to improve head quality.

Commercial Field Schedule (Per Acre)

Pre-Plant: Broadcast 800-1,000 lbs of 10-10-10 and incorporate 2-4 weeks before planting.

Week 3-4 (First Side-Dress): Apply 50-60 lbs actual nitrogen using 110-130 lbs urea (46-0-0) OR 150-175 lbs ammonium nitrate (34-0-0). Band 4-6 inches from plants and irrigate immediately.

Week 6-7 (Second Side-Dress): Apply 40-60 lbs of actual nitrogen using the same rates and methods.

Fertigation Alternative:

  • Weeks 1-2: 3-5 lbs N per week
  • Weeks 3-6: 8-12 lbs N per week
  • Weeks 7-10: 12-15 lbs N per week
  • Weeks 11+: 8-10 lbs N per week

Nutrient Deficiency Solutions

Nitrogen (yellow older leaves): Home: 1/4 cup blood meal per plant. Field: 110-130 lbs of urea per acre.

Phosphorus (purple leaves): Home: 2 tablespoons bone meal per plant. Field: 175-260 lbs of superphosphate per acre.

Calcium (hollow stems): Home: 1/4 cup lime per plant. Field: 320-390 lbs calcium nitrate per acre.

Magnesium (yellowing between veins): Home: 1 tablespoon Epsom salt per gallon of water. Field: 20-40 lbs Epsom salt per acre.

Pest Management

Major Pests

Cabbage Worms/Loopers (green caterpillars):

  • Home control: Hand-pick daily, use row covers, spray Bt (1-2 tablespoons per gallon) weekly
  • Commercial control: Bt products (Dipel DF 0.5-2 lbs per acre every 5-7 days), Spinosad (4-8 oz per acre)
  • Threshold: 0.3 larvae per plant before heading, 0.1 during heading

Aphids (small sucking insects):

  • Home control: Spray with water and insecticidal soap (2-5 tablespoons per gallon every 3-5 days)
  • Commercial control: Insecticidal soap (1-2% solution, 50-100 gallons per acre), Imidacloprid (4-8 oz per acre)
  • Threshold: 10% of plants infested

Flea Beetles (tiny jumping beetles):

  • Home control: Row covers, kaolin clay spray (2-4 tablespoons per gallon)
  • Commercial control: Carbaryl (1-2 lbs per acre) on young plants
  • Threshold: 10-20% defoliation on young plants

Cabbage Root Maggots:

  • Home control: Place 4-inch cardboard collars around stems, use row covers
  • Commercial control: In-furrow insecticide at transplanting, beneficial nematodes

Disease Management

Clubroot (swollen roots, wilting):

  • Prevention: Maintain pH above 7.2, rotate crops 7 years
  • Control: Remove infected plants immediately; no cure available

Black Rot (V-shaped yellow lesions):

  • Prevention: Use certified seed, drip irrigation, crop rotation 2-3 years
  • Control: Copper spray (1-2 tablespoons per gallon home; 1-2 lbs per acre commercial) weekly in wet weather

Downy Mildew (gray fuzz on leaves):

  • Prevention: Good spacing (18-24 inches), morning watering
  • Control: Copper fungicide every 7-10 days; commercial: Mancozeb (2-3 lbs per acre)

Harvesting

Timing

Harvest when heads are 4-7 inches in diameter with tight, compact buds and deep green color. Timing varies by variety: early (50-60 days), mid-season (60-75 days), and late (75-85 days) from transplanting. Harvest in the early morning when temperatures are cool.

Technique

Home Gardens: Use a sharp knife or pruning shears. Cut 5-6 inches below the head at 45-degree angle. Handle carefully to avoid bruising. After the main harvest, leave the plant for side shoot production (4-6 weeks of additional harvest, 1-2 lbs per plant).

Commercial Fields:

  • Hand harvest: Cut and pack in field, 14-18 heads per 20-23 lb carton
  • Harvest every 2-3 days during peak (2-4 week window)
  • Cool immediately: Hydrocool to 32-34°F or forced-air cool within 2 hours
  • Expected yields: 15,000-25,000 lbs per acre with good management

Storage

Home: Refrigerate at 32-35°F with high humidity (95-100%) for 7-10 days. Don't wash until ready to use.

Commercial: Store at 32°F with 95-100% humidity for a maximum of 14-21 days. Ship refrigerated (32-36°F).

Common Problems and Solutions

Small heads: Increase water (1.5-2 inches weekly during heading), apply 1/4 cup blood meal per plant, and provide shade if temperatures exceed 75°F.

Premature bolting: Plant for optimal temperature window, maintain consistent moisture, and use bolt-resistant varieties.

Hollow stems: Apply borax (1/2 teaspoon per gallon of water at home) or calcium nitrate (field), maintain consistent watering, and avoid excessive nitrogen late in growth.

Uneven maturity (commercial): Use uniform-sized transplants, check irrigation uniformity, and adjust fertility by field zones.

Yellow leaves: Apply nitrogen immediately if deficient (1/4 cup blood meal at home; 110-130 lbs urea per acre in the field); improve drainage if waterlogged.

Key Success Factors

  1. Temperature control: Keep plants in 60-70°F range; use row covers for cold protection and shade cloth when hot
  2. Consistent moisture: Never stress plants, especially during head formation (weeks 8-12)
  3. Heavy feeding: Apply nitrogen regularly; broccoli requires more nutrients than most vegetables
  4. Pest prevention: Use row covers from planting, practice 3-4 year crop rotation
  5. Timely harvest: Quality deteriorates rapidly when over-mature; harvest every 2-3 days at peak

For home gardeners, start with 10-15 plants and succession plant every 2-3 weeks for extended harvest. For commercial growers, focus on variety selection for your market, proper spacing for target head size, and labor management during the critical 2-4 week harvest window.