Planting Leeks in the UK: A Complete Step-by-Step Guide for Gardeners

Introduction

Leeks are one of the most reliable and flavourful winter crops you can grow in the UK. With their mild onion flavour, cold resistance, and long harvest window, they’re perfect for soups, pies, tarts, and roasts.

But success with leeks starts from the beginning — and learning how to plant leeks properly makes a big difference in stem size, flavour, and harvest quality.

In this article, we’ll show you when, where, and how to plant leeks, whether you’re sowing indoors, transplanting outdoors, or growing in containers. We’ll also cover spacing, watering, companion plants, and tips to avoid common pitfalls.

Why Grow Leeks?

✅ Hardy in UK winters — survives frost and snow
✅ Long harvest window — from September to April
✅ Minimal pest problems compared to other crops
✅ Stores well in the ground
✅ Full of vitamins, fibre, and flavour

Leeks are a true low-maintenance crop that keeps on giving when little else is growing.

When to Plant Leeks in the UK

Sowing in trays indoors gives you an early start and stronger seedlings, especially in cooler regions.

Best Varieties of Leeks for UK Gardens

Choose a mix of early and late varieties for a longer harvest.

How to Plant Leeks: Step-by-Step Guide

🪴 Step 1: Sow Seeds Indoors

• Fill trays or pots with seed compost
• Sow seeds 1cm deep and spaced thinly
• Keep warm (15–20°C) on a windowsill or propagator
• Germination takes 10–14 days

Grow until seedlings are 15–20cm tall and pencil-thick — this takes 8–10 weeks.

🌿 Step 2: Prepare the Outdoor Bed

• Choose a sunny, sheltered spot
• Fork in well-rotted manure or compost
• Rake level and remove weeds
• Water well a day or two before transplanting

Avoid freshly manured beds — this can cause misshapen leeks.

🌱 Step 3: Transplant Seedlings Using the Dibbing Method

The traditional UK “dib and drop” technique creates long, white stems.

How to Do It:

1. Use a dibber to make 15–20cm deep holes, spaced 15cm apart
2. Space rows 30cm apart
3. Drop one seedling into each hole
4. Do not backfill — instead, water into each hole to settle the roots

As leeks grow, soil gradually fills in, blanching the stems naturally.

🧅 Step 4: Watering and Feeding

• Water regularly, especially in dry spells or just after transplanting
• Mulch around plants to retain moisture and suppress weeds
• Feed every few weeks with seaweed extract, comfrey tea, or diluted liquid feed

Once established, leeks are relatively drought-tolerant — but consistent moisture leads to thicker stems.

Spacing Guide for Planting Leeks

Wider spacing = larger leeks. Closer spacing = smaller, slender leeks, ideal for soups.

Growing Leeks in Containers or Raised Beds

Leeks do very well in raised beds and pots.

Container Tips:

• Use containers 30cm deep minimum
• Fill with a mix of soil-based compost and organic matter
• Space 10–12cm apart
• Water and feed regularly

Ideal for balconies, patios, or small gardens.

Companion Planting with Leeks

Leeks work well with:

✅ Carrots – leeks deter carrot fly
✅ Celery, onions, and brassicas – similar soil and water needs
✅ Beetroot and lettuce – interplant between rows

Avoid planting near peas or beans, which dislike alliums.

Common Mistakes When Planting Leeks

Good prep = good crops. Be patient and methodical when planting leeks.

How Long Do Leeks Take to Grow?

Leeks take 5 to 7 months from seed to full harvest size.

Pick as needed — leeks can stay in the ground until you’re ready to use them.

Can You Plant Leeks from the Supermarket?

Yes, but with mixed results.

• Trim down to the white base (2–3cm of root)
• Place in water until roots appear
• Replant into soil

Better for fun or emergency use — not as productive or disease-resistant as seed-grown varieties.

Bonus: How to Get Extra-Long White Stems

• Use the dibbing method at transplant
• Gradually earth up the base over time
• Use collars or tubes for straight, blanched stems
• Mulch heavily around plants as they grow

Longer white stems = sweeter flavour and better texture.

Conclusion

Planting leeks is easy once you understand the timing, spacing, and traditional methods like dibbing. Whether you’re filling up an allotment bed or popping a few into containers, leeks are low-fuss, high-reward vegetables that thrive in the UK climate.

With a little patience and care, you’ll enjoy a harvest of thick, flavourful leeks ready for soups, pies, and winter warmers — just when you need them most.

Top 10 Questions and Answers About Planting Leeks

1. When should I plant leeks in the UK?

Sow indoors from January to March, and plant out April to July.

2. How deep should I plant leek seedlings?

Use a dibber to create holes 15–20cm deep, and drop seedlings in.

3. What’s the best spacing for planting leeks?

15cm apart in rows 30cm apart is ideal for standard kitchen leeks.

4. Can I plant leeks in pots?

Yes — use deep pots and space plants 10–12cm apart.

5. Do I fill in the hole when transplanting leeks?

No — water the seedling into the hole. Soil will settle around the plant gradually.

6. Can I use supermarket leeks to grow more?

You can regrow them, but they’re less reliable than seed-grown plants.

7. Should I trim leek roots and leaves before transplanting?

Optional — trimming can help reduce transplant shock.

8. How long do leeks take to grow?

Typically 5–7 months from seed to harvest, depending on variety.

9. Can I leave leeks in the ground over winter?

Yes — they are frost-hardy and will store well in soil until needed.

10. What’s the best soil for planting leeks?

Light, well-drained soil enriched with compost or aged manure (not fresh).