🌱 Leek

Leeks are one of the best winter vegetables: hardy, productive and happy in a wide range of soils, and they are ready to harvest when little else is. They grow slowly, so a March sowing gives you a crop from autumn right through to spring.

They are very forgiving, and take little attention other than watering and weeding, making them a great choice for beginners. Planting them in deep holes (dibbling) is the traditional way to get long, blanched white stems.

Types and varieties

Leeks are early, mid or late, and the choice sets how long the row lasts.

Sow in March and April, either in trays or modules indoors, or thinly in a seedbed outdoors, 1 cm deep. Seedlings look like thin blades of grass and are slow to start. Keep them watered and weeded until they are about as thick as a pencil, which takes 8–12 weeks.

In June or July, transplant them into their final position. Use a dibber to make holes 15 cm deep and 15 cm apart, in rows 30 cm apart. Trim the roots and leaf tips, drop one leek into each hole and water in, letting the water wash soil around the roots. Do not fill the holes with soil.

Top tips

• Transplant when seedlings are pencil-thick.
• Do not fill the dibbed holes; water settles the soil.
• Trim leaf tips by a third before planting.
• Interplant with quick catch crops like radishes.

Water in dry spells and keep weeds down while plants are young. Feed with a general fertiliser every few weeks through the summer. As the leeks swell, gradually draw soil up around the stems, a process called earthing up, to blanch the stems and keep them white and tender.

The main problems are leek rust (orange spots on the leaves), leek moth, allium leaf miner and white rot. Rust-resistant varieties and wide spacing help; cover with fine mesh to keep out moths and leaf miners. Rotate leeks with other onion-family crops.

Top tips

• Earth up gradually in late summer for longer white stems.
• Net with fine mesh against leek moth and leaf miner.
• Choose rust-resistant varieties.
• Feed in summer and stop in autumn.

Watch out for

Leek rustLeek mothAllium leaf minerOnion white rot

Lift leeks from September through to April, when they are at least 2 cm across. Early varieties are ready first, while hardy types stand all winter. Loosen the soil with a fork alongside the row and lift the whole plant, taking care not to snap the stem.

Leeks stand well in the ground, so lift only what you need. In freezing weather, harvest before the soil is frozen solid. In spring, lift any remaining leeks before they run to seed, when they develop a hard central core.

Top tips

• Lift a few at a time throughout autumn and winter.
• Use a fork rather than pulling by hand.
• Take out all leeks before they bolt in spring.
• Leave small ones to grow on.

Slice leeks into soups, pies and stews, braise them in butter, bake them in a cheese sauce, or use as the base of potato and leek soup. Smaller baby leeks are tender enough to eat whole with vinaigrette. The dark green tops are tougher but work well in stock.

Trim the roots and tops, wash off any soil between the layers, and keep in the fridge in a bag for up to two weeks. Leave hardy leeks in the ground until needed. For the freezer, slice, blanch for two minutes, drain well and freeze in portions.

Top tips

• Slice and wash thoroughly to remove grit trapped between layers.
• Use the dark green tops for stock.
• Blanch for two minutes before freezing.
• Cook slowly in butter to bring out the sweetness.