Growing Broccoli on an Allotment

Broccoli is a nutritious, productive brassica that rewards steady care with generous harvests. While it has a reputation for being tricky, most problems come down to spacing, feeding, and pest protection. Get those right and broccoli becomes a dependable crop in both ground beds and large containers.

This guide covers how to grow broccoli from seed or plug plants, when to plant, spacing, watering and feeding, pests and diseases, container vs ground growing, and proven ways to improve yields.

🌱 1. Types of Broccoli You Can Grow

🥦 Calabrese (Green Broccoli)

• Large central head

• Produces side shoots after cutting

• Fast growing (summer–autumn harvest)

🥦 Purple Sprouting Broccoli

• Multiple small shoots

• Overwinters and crops in late winter–spring

• Very hardy, slower growing

(Growing methods are similar, but timings differ.)

🌰 2. Ways to Grow Broccoli

From Seed

Pros

• Cheapest option

• Wide variety choice

• Strong root systems

Cons

• Needs protection when young

Plug Plants

Young broccoli plants grown in modules.

Pros

• Faster establishment

• Less early pest damage

• Ideal for beginners

Cons

• More expensive

• Limited varieties

👉 Both methods work well — soil fertility and pest protection matter more than starting method.

🗓️ 3. When to Sow & Plant Broccoli

Calabrese

• Sow indoors: Feb–April

• Sow outdoors: April–May

• Plant out: April–June

• Harvest: June–October

Purple Sprouting Broccoli

• Sow: March–April

• Plant out: May–June

• Harvest: Feb–April (following year)

Broccoli prefers cool, steady growing conditions.

🌾 4. How to Grow Broccoli in the Ground

Soil & Position

• Firm, fertile soil

• Sunny, open site

• Plenty of organic matter added before planting

Brassicas grow best in soil that has been manured the previous season, not freshly fed.

Spacing (Very Important)

• Between plants: 45–60cm

• Between rows: 60cm

Crowded broccoli produces:

• small heads

• weak plants

• more pest problems

Planting Tips

• Plant firmly (brassicas like firm soil)

• Water in well

• Add a collar around stems to deter pests

🪴 5. Growing Broccoli in Containers

Broccoli can be grown in containers with enough space.

Container Guidelines

• Minimum size: 30–40 litres per plant

• One plant per pot

• Rich, moisture-retentive compost

Containers need more frequent watering and feeding.

💧 6. Watering Broccoli

Consistent moisture is key.

Best Practice

• Water deeply and regularly

• Avoid letting soil dry out

• Mulch to retain moisture

Dry stress causes:

• buttoning (tiny heads)

• bitter flavour

• premature bolting

🌿 7. Feeding Broccoli

Broccoli is a heavy feeder.

Feeding Schedule

• Compost or manure before planting

• Start liquid feeding once established

• Feed every 2–3 weeks with a balanced feed

Lack of nutrients = small heads and yellowing leaves.

🐛 8. Common Pests & Diseases

Cabbage White Caterpillars

Symptoms

• Holes in leaves

• Green caterpillars present

Control

• Fine mesh netting

• Hand removal

• Encourage birds

Aphids

• Cluster on new growth

• Cause distortion

Wash off with water or remove by hand.

Clubroot (Soil Disease)

Symptoms

• Wilting plants

• Swollen, distorted roots

Prevention only

• Long crop rotation

• Improve drainage

• Lime acidic soils

✂️ 9. Harvesting Broccoli

Calabrese

• Cut main head while tight

• Side shoots will follow

Purple Sprouting

• Harvest spears regularly once cropping begins

Harvesting promptly:

• improves quality

• extends cropping period

🌾 10. Improving Broccoli Yields

• Space plants generously

• Keep soil consistently moist

• Feed regularly

• Protect from pests early

• Harvest on time

Broccoli rewards steady, stress-free growing.

⚡ Quick Broccoli Growing Tips

• Firm soil = stronger plants

• Net plants from day one

• Don’t rush planting in hot weather

• Side shoots extend harvests

🧠 Key Broccoli Principles

• Space and firmness matter

• Moisture prevents buttoning

• Feeding improves head size

• Netting prevents most pest issues

Photo by KC Shum on Unsplash