Leeks are dependable, hardy alliums with a mild onion flavour and a valuable long season. Given time and fertile ground, they make substantial stems for the kitchen and can remain in the plot through winter, providing crops from autumn into spring.

When and how to sow

Sow from February to April in module trays under cover, or in a well-prepared seed bed outdoors from March. Choose an open, sunny site with deep, moisture-retentive soil enriched with garden compost. Transplant pencil-thick young plants from May to July, 15 cm apart. Make deep holes with a dibber, drop each plant in and water thoroughly to puddle the roots.

Care

Keep leeks watered during dry spells and weed carefully, as early growth is slow. Mulch with compost to retain moisture. As stems lengthen, draw loose soil around their bases in stages for longer white shanks, without allowing soil between the leaves. Rotate alliums around the allotment each year.

Common problems

Leek rust causes orange-brown pustules, particularly in crowded or dry crops; remove affected leaves and improve spacing. Allium leaf miner and leek moth larvae can damage stems and foliage. Cover crops with insect-proof mesh or fleece when pests are active, and clear away damaged plants promptly.

Harvest

Lift leeks from late summer once stems are useful-sized, using a fork to loosen stubborn soil. Leave hardy varieties in the ground for winter picking, taking plants as required before they begin to run to seed in spring. Shake off soil, trim roots and wash thoroughly between the leaves.

Growing Leeks: frequently asked questions

When should I sow leeks in the UK?

Sow from February to April in module trays under cover, or in a well-prepared seed bed outdoors from March.

What are common problems when growing leeks?

Leek rust causes orange-brown pustules, particularly in crowded or dry crops; remove affected leaves and improve spacing.

When is leeks ready to harvest?

Lift leeks from late summer once stems are useful-sized, using a fork to loosen stubborn soil.

General guidance for UK home gardens and allotments. Reference figures are typical values; your exact timing depends on your region, last-frost date and variety. Page updated 19 Sep 2026.