Growing Leeks from Seed

Leeks are a fantastic vegetable to grow in your garden, offering a mild, sweet flavour perfect for many British dishes. They are easy to cultivate and, with a bit of patience, you can enjoy homegrown leeks from late summer through to the winter months. This guide will walk you through the process of growing leeks from seed, covering sowing times, transplanting, care, and harvesting. 

When to Sow Leek Seeds

Leeks are best sown in early spring for transplanting later in the season. In milder climates, you can also sow in late summer for a late autumn or winter harvest. Keep in mind that leeks are slow-growing, so timing is essential for success. 

  • Northern climates: Sow from late winter to early spring, ideally February to March. 

  • Southern climates: Sow in spring or late summer for a harvest from autumn to winter. 

Sowing Indoors

 

Sowing leek seeds indoors allows you to get a head start on the growing season, especially in cooler climates. 

  1. Prepare trays: Fill seed trays or pots with sieved, peat-free compost. 

  1. Sow seeds: Scatter leek seeds thinly, about 1 inch (2-3 cm) apart. For module trays, sow two seeds per cell. 

  1. Cover and water: Gently cover with a thin layer of compost and water gently. 

  1. Provide warmth: Place trays in a warm location, such as a sunny windowsill or greenhouse, for faster germination. 

Sowing Outdoors

 

Leeks can also be sown directly outdoors, though it’s generally recommended to start indoors and transplant later. 

  1. Prepare the soil: Choose a well-draining, fertile spot with full sun. 

  1. Sow directly: If you prefer sowing directly outdoors, sow the seeds 1 inch (2-3 cm) apart in shallow drills. 

  1. Keep moist: Water the soil regularly, ensuring it stays moist during germination. 

Transplanting Leeks

 

Once your leek seedlings are 6-8 inches (15-20 cm) tall, it’s time to transplant them into their final growing positions. 

  1. Harden off: Acclimatise seedlings to outdoor conditions by gradually increasing their exposure to the elements over 1-2 weeks. 

  1. Prepare the holes: Use a dibber or similar tool to make holes around 6 inches (15 cm) apart. 

  1. Plant the seedlings: Gently remove seedlings from their pots, trimming any long roots as necessary. Place them in the holes, ensuring the roots are fully submerged. 

  1. Water well: After planting, water the seedlings thoroughly to settle the soil. 

How to Sow Leek Seeds

 

Leeks require a bit more patience than other vegetables, so be sure to start your seeds early and keep the growing environment warm. Sow seeds indoors in late winter or early spring, about 1 inch (2-3 cm) apart in trays or pots filled with good-quality, peat-free compost. 

How deep should I sow Leek Seeds?

 

Leek seeds should be sown about 1 inch (2-3 cm) deep. Once sown, gently cover them with a thin layer of compost and water them gently to avoid displacing the seeds. 

Leek Growing Requirements (Caring for Leeks)

Watering

 

Leeks need consistent moisture, so water them regularly, especially in dry spells. Ensure the soil stays moist but not waterlogged. 

Mulching

 

Apply a layer of mulch around your leeks to retain moisture and suppress weeds. 

Weeding

 

Weeds can compete with leeks for nutrients, so keep the area weed-free. Hand-weeding or using a hoe regularly is important. 

Protection

 

Leeks are generally pest-free, but you may want to use horticultural fleece to protect them from harsh frost or strong winds. 

Blanching Leeks

 

Blanching leeks will give you the long, white stems that are prized for their flavour. About 2-3 weeks before harvest, draw soil up around the stems to exclude light or use cardboard tubes to cover them. This process can help increase the size of the white shanks. 

Leek Pests & Diseases

 

While leeks are relatively pest-free, there are a few issues to watch out for: 

  • Thrips: Small pests that can damage leaves. Control by removing infested leaves. 

  • Maggots: Root maggots can infest leeks. Crop rotation and netting can help. 

  • Fungal diseases: Ensure good air circulation and avoid overcrowding to prevent fungal issues. 

Flowering or Bolting Leeks

 

Leeks can flower (bolt) in hot weather or if they are stressed, causing them to produce seeds. This can affect the quality of the edible part of the leek, so if your leeks begin to bolt, it’s best to remove the flowers and harvest the leeks earlier than planned. 

When & How to harvest leeks

 

Leeks are ready to harvest when they reach the desired size, typically in late summer through to winter. 

  1. Loosen the soil: Use a fork to gently lift the leeks from the ground. 

  1. Trim roots: Remove the roots and any damaged or unnecessary leaves. 

  1. Wash: Clean the leeks thoroughly to remove any soil before use. 

You can leave hardy varieties in the ground throughout the winter if the weather permits, but harvest before the ground freezes in colder areas. 

Storing Leeks

 

Leeks can be stored in a cool, dark place, or they can be frozen for longer storage. To freeze, simply blanch the leeks in boiling water for a few minutes before freezing them. 

Growing Success Tools

 

For optimal leek-growing success, these tools and products will help you get the best results: 

  • Gro-Sure Seed & Cutting Compost (10904094): A high-quality, peat-free compost designed to promote strong seedling growth and healthy root development. 

  • Plantpak Half Seed Tray Kit x 10 (10903396): Ideal for sowing leek seeds indoors. These trays help to keep seeds organised and provide a controlled environment for early growth. 

  • Gro-Sure Perlite (10904037): Helps improve drainage and aeration in compost, providing leeks with the optimal growing conditions for root development and moisture retention. 

 

With this step-by-step guide, you can confidently grow leeks in your garden, enjoying their delicate flavour and versatility in your kitchen. Happy sowing and harvesting! 🌱 

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