How to grow leek
Overview
Leek (Allium ampeloprasum) is a cool-season vegetable grown for its long, savoury stems and mild onion flavour. It is a kitchen-garden staple that thrives in full sun and requires steady moisture for best growth.
Varieties
- Musselburgh — A reliable, cold-tolerant variety with thick stems, ideal for cooler zones.
- Blue Solaise — A blue-green leek with excellent flavour and good frost resistance.
- King Richard — An early-maturing variety with long, slender stems, good for quick harvests.
Soil Preparation
Leek prefers well-drained, fertile soil with a pH of 6.0–7.0. Add compost or well-rotted manure before planting, and ensure good drainage to avoid root rot.
Growing Guide
Sow leek seed in punnets or direct into beds 6 mm deep, spacing 10 cm apart in rows 30 cm apart. Transplant seedlings when 15 cm tall, planting them deeply into a 15 cm deep trench to blanch stems. Gradually fill the trench with soil as they grow to produce long white stems. Keep soil consistently moist but not waterlogged, and water at the base to avoid rust.
Sowing
Sow leek seed 6 mm deep in punnets or direct into beds, spacing 10 cm apart. Germination takes 7–14 days at 15–20°C. Direct sow is fine, but transplanting gives stronger plants and longer stems.
Care
Feed leek monthly with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) or apply a slow-release pellet at transplant. Remove any flower stalks that appear to focus energy on the stem. Keep beds weed-free and mound soil around stems as they grow to blanch them.
Companion Planting
Leek grows well with carrot, celery, and brassicas like broccoli and cabbage. Avoid planting near beans, peas, and other alliums such as onion and garlic to reduce pest and disease pressure.
Common Pests & Risks
Thrips cause silver streaks on leaves; control with neem oil or insecticidal soap. Rust appears as orange pustules; improve air circulation and avoid overhead watering. Onion maggot attacks roots; use row covers and rotate crops.
Harvesting
Harvest leek when stems are 2–3 cm thick at the base, usually 4–6 months after transplant. Lift with a fork to avoid damaging the stem, and store in the fridge for up to 3 weeks.
In the Kitchen
Use leek stems raw in salads or cooked in soups, stews, and stir-fries. Store in the fridge for up to 3 weeks; wash thoroughly before use to remove soil.
Troubleshooting
Yellow leaves: overwatering or poor drainage; reduce water and improve soil. Brown leaf edges: wind or sun scorch; provide shade or windbreak. Rust: fungal disease from overhead watering; water at base and improve air circulation. Thrips: silver streaks on leaves; use neem oil. Onion maggot: stunted growth; use row covers and rotate crops.