Growing Leeks on an Allotment

Leeks are a long-season, low-maintenance crop that earn their space on the allotment. They’re hardy, stand in the ground through winter, and provide fresh harvests when little else is available. While they take time to mature, leeks are forgiving and ideal for growers who prefer steady progress rather than constant attention.

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

🌱 1. Ways to Grow Leeks

🌰 Growing Leeks from Seed (Most Common)

The traditional and most economical method.

Pros

• Cheapest option

• Best variety choice

• Strong, adaptable plants

Cons

• Long growing season

• Need transplanting

🌱 Leek Plug Plants

Young leek plants supplied in modules.

Pros

• Faster start

• Less early care

• Ideal for beginners or late sowing

Cons

• More expensive

• Limited varieties

👉 Both methods work well — spacing, watering, and soil quality matter more than how you start.

🗓️ 2. When to Sow & Plant Leeks

From Seed

• Sow indoors: Jan–Feb

• Sow outdoors: Mar–Apr

• Transplant: May–July

Plug Plants

• Plant out: May–July

Leeks are hardy once established and tolerate cold well.

🌾 3. How to Grow Leeks in the Ground

Soil Requirements

• Moisture-retentive but free-draining soil

• High organic matter

• Open, sunny position

Leeks are heavy feeders and benefit from compost-rich soil.

Spacing

• Between plants: 15–20cm

• Between rows: 30cm

Wider spacing produces thicker leeks.

Planting Method (Traditional Leek Planting)

1. Make holes 15–20cm deep using a dibber

2. Drop one plant into each hole

3. Water well and allow soil to wash in naturally

Do not fill holes with soil — this helps blanch the stems.

🪴 4. Growing Leeks in Containers

Leeks grow well in containers if depth is sufficient.

Container Guidelines

• Depth: at least 30cm

• Spacing: 3–5 leeks per large pot

• Rich, moisture-retentive compost

Container leeks need more frequent watering and feeding.

💧 5. Watering Leeks

Leeks have shallow roots and need consistent moisture.

Best Practice

• Water regularly during dry spells

• Focus on soil, not leaves

• Mulch to retain moisture

Drought stress causes:

• thin stems

• slow growth

🌿 6. Feeding Leeks

Leeks are heavy feeders compared to onions.

Feeding Schedule

• Add compost or manure before planting

• Apply liquid feed every 2–3 weeks in summer

• Avoid excess nitrogen late in the season

Healthy soil = thick, tender leeks.

🐛 7. Common Pests & Diseases

Leek Moth

Symptoms

• Holes and damage inside leaves

Control

• Fine mesh netting

• Remove affected leaves

Allium Leaf Miner

• Lines or tunnels in leaves

• Increasingly common

Prevention

• Mesh covers

• Avoid planting during peak activity

Leek Rust

Symptoms

• Orange pustules on leaves

Control

• Good spacing

• Remove badly affected leaves

• Improve airflow

🧺 8. Harvesting Leeks

When to Harvest

• Harvest from late summer through winter

• Leeks can stay in the ground until needed

How to Harvest

• Loosen soil gently

• Lift carefully to avoid snapping

Leeks improve in flavour after light frost.

🌾 9. Improving Leek Yields

• Start early from seed

• Feed regularly in summer

• Space plants generously

• Keep soil moist

• Weed thoroughly

Leeks reward time and consistency, not rushing.

⚡ Quick Leek Growing Tips

• Don’t overfill planting holes

• Wider spacing = thicker leeks

• Mulch in summer to reduce watering

• Harvest as needed — no rush

🧠 Key Leek Principles

• Long season, steady care

• Moist soil = tender stems

• Feeding improves size

• Spacing affects thickness