How to Plant Leeks for a Long Harvest: A Complete Guide

Introduction

Leeks are a classic crop in British gardens and allotments—hardy, versatile, and perfect for extending your harvest into the colder months. Whether you’re looking to grow a few leeks for homemade soups or a steady supply through winter, learning how to plant leeks for a long harvest is a worthwhile investment for any gardener.

In this comprehensive guide, we’ll walk you through everything you need to know to grow leeks successfully—from sowing and transplanting to harvesting and storage. Whether you’re a beginner or a seasoned grower, this guide will help you enjoy fresh, flavourful leeks from summer to spring.

Why Grow Leeks at Home?

🌿 Cold-hardy and resilient: Leeks survive winter frosts with ease.
🧅 Space-efficient: Suitable for raised beds, garden borders, or rows.
🥣 Great in the kitchen: Delicious in soups, pies, stir-fries, and more.
🌱 Long harvest window: From late summer to early spring.
💷 Cost-saving: Homegrown leeks are cheaper and fresher than store-bought ones.

Types of Leeks for Different Harvest Times

There are two main categories of leeks:

Type	Harvest Period	Variety Examples
Summer Leeks	August to October	Carlton F1, King Richard, Oarsman F1
Autumn/Winter	November to February	Musselburgh, Bandit, Autumn Giant
Overwintering	February to April	Blauwgroene Winter, Atlanta, Bleu de Solaise

Tip: To enjoy a long harvest, stagger your sowing and grow a mix of early and late-season varieties.

When to Plant Leeks in the UK

Task	Timing
Sow indoors	January to March
Sow outdoors (direct)	March to April
Transplant seedlings	May to June
Harvest (early varieties)	August to October
Harvest (late varieties)	November to April

Step-by-Step Guide to Planting Leeks for a Long Harvest

Step 1: Start Seeds Indoors or Outdoors

Indoor Sowing (Recommended for an Early Start):

Sow January to March in trays or pots
Use seed compost and sow thinly
Keep in a bright, cool spot (~15°C)
When seedlings are pencil-thick (about 15–20cm tall), transplant outside

Outdoor Sowing:

Sow March to April directly into a seedbed or prepared soil
Sow in rows 1cm deep and 15cm apart
Thin to 3–5cm once established

Step 2: Prepare the Planting Site

Leeks thrive in:

Sunny, open positions
Well-drained, fertile soil
Neutral to slightly alkaline pH (6.5–7.5)

Soil Preparation:

Dig in well-rotted compost or manure the autumn before planting
Rake in a balanced general-purpose fertiliser (e.g., Growmore) in spring
Avoid planting where onions, garlic, or other alliums were grown last year

Step 3: Transplanting Leeks

When your seedlings are pencil-thick (usually by May or June), they’re ready to go into their final growing position.

How to Transplant Leeks:

Make holes 15–20cm deep and 15cm apart using a dibber or stick.
Drop one leek seedling into each hole without backfilling.
Water into the hole—this settles soil around the roots.
As leeks grow, soil naturally fills the holes.

Why this method? It helps produce long, white stems—the desirable part of the leek.

Caring for Your Leeks

1. Watering

Water regularly during dry periods
Keep soil moist but not soggy

2. Feeding

Apply a nitrogen-rich feed (e.g., chicken manure pellets) 3–4 weeks after transplanting
Top-dress with compost or mulch for slow-release nutrition

3. Weeding

Keep the area around leeks weed-free—leeks don’t compete well

4. Earthing Up

For whiter stems, mound soil up around the base of the leek as it grows
Be gentle—don’t bury leaves or they may rot

Companion Planting with Leeks

Leeks are great companion plants for many vegetables:

Good Companions:

Carrots (leeks repel carrot root fly)
Celery
Lettuce
Strawberries

Avoid Planting Near:

Legumes (beans and peas may not do well nearby)
Other alliums (onions, garlic) to prevent disease build-up

Common Leek Problems and Solutions

Problem	Symptoms	Solution
Leek Moth	Caterpillars inside leaves	Cover with insect mesh, rotate crops
Allium Leaf Miner	Leaf tunnels and distorted growth	Use mesh, avoid growing near other alliums
Rust	Orange pustules on leaves	Improve air flow, remove affected leaves
Slow growth	Thin, weak stems	Feed with nitrogen-rich fertiliser

Harvesting Leeks

When to Harvest:

Early varieties: August to October
Maincrop varieties: November to February
Overwintering leeks: February to April

Harvest when stems reach 2–5cm in diameter, depending on your preference.

How to Harvest:

Use a fork to loosen soil around the base
Pull gently from the base to avoid snapping
Leave small ones to grow on if harvesting over time

Storing and Preserving Leeks

In the Ground:

Leeks can be left in the soil over winter and harvested as needed

In the Fridge:

Trim roots and leaves, then store in a bag for up to 10 days

Freezing Leeks:

Wash and slice into rounds
Blanch in boiling water for 1–2 minutes
Cool, drain, and freeze in bags

Growing Leeks in Containers or Raised Beds

Leeks can grow well in containers if deep enough.

How-To:

Use a deep container (30cm+)
Space seedlings 10–15cm apart
Fill with rich compost and loam mix
Water and feed regularly
Ideal for small gardens or patios

How to Plan for a Long Harvest

1. Stagger Sowing:

Sow early, mid, and late varieties 2–3 weeks apart for a continuous supply

2. Choose Different Varieties:

Grow a mix of early, maincrop, and overwintering types

3. Store Late Crops In-Ground:

Keep hardy leeks in the ground and lift as needed in winter

4. Use Succession Planting:

Start with fast-growing crops (e.g., lettuce) in spring, then transplant leeks in their place

Conclusion

Leeks are a must-grow crop for UK gardeners who want a steady, reliable harvest throughout the year. By choosing the right varieties, preparing your soil well, and following this step-by-step planting method, you’ll enjoy homegrown leeks from late summer all the way through spring.

Whether you’re planting in rows, raised beds, or pots, leeks are hardy, low-maintenance, and flavour-packed—ideal for everything from hearty stews to gourmet meals.