Leek

Origin & history

The leek descends from wild Allium ampeloprasum of the Mediterranean and was everyday food for Egyptians and Romans alike; the Romans carried it across the Alps, and Charlemagne’s estate ordinance of around 800 lists it as “porros” among the compulsory crops. Botanically it forms no bulb at all: the white shank consists of tightly rolled leaf sheaths layered like sheets of paper. In Wales the leek is still a national symbol, worn on the lapel on St David’s Day.

Varieties

Leeks come as summer, autumn and winter types, and when buying seed that is the only question that really matters. Summer varieties have pale green foliage and long, slender shanks and are ready from September, but they take no hard frost; winter types are recognisable by the dark blue-green of their leaves — they stay shorter and thicker, but stand in the bed into spring. Almost all common varieties are open-pollinated; if you would rather not raise plants for ten weeks yourself, buy bundled young plants in May or June.

Care

Leeks want steady moisture right through the season and a moderate feed in July, when the shank thickens — through longer dry spells they stay thin and stringy. Earthing up carefully two or three times lengthens the white part further, but never higher than just below the point where the leaves split: soil that slips between the leaf sheaths never comes out again and grits up the soup later. Keep the bed weed-free, because the narrow, upright leaves cast almost no shade and weeds have a clear run.

What can go wrong

Leek moth and leek miner fly are the two serious opponents: both eat tunnels and window-like patches into the heart of the plant, and only a fine-mesh crop-protection net keeps them out — left on from planting until November, because the second generation of the fly is not on the wing before October. Leek rust shows up as orange pustules on the leaves, usually in a damp late summer; generous spacing, restrained nitrogen and stripping off the affected outer leaves are entirely enough, and the harvest is not at risk from it. Do not bring leeks or other alliums back onto the same bed for three to four years.

Harvest, storage & kitchen

Leek is its own store: winter varieties come fresh out of the bed all winter long, and in a prolonged freeze a covering of leaves or fleece keeps the soil looser and the harvest possible. Lift them with a digging fork rather than pulling, or the shank tears off. In the kitchen slit the shank lengthways and rinse between the layers — that is where the grit sits; the dark green top is too tough to fry but the best thing you can put into a stock.

Frequently asked questions

Is leek the same thing as chives?

No — chives are a fine, perennial kitchen herb that grows happily in a pot and never forms a thick shank, whereas a leek is grown for exactly that shank. In German the vegetable goes by two names, Lauch and Porree, but they are one and the same plant.

When do you start leeks off under cover?

From late February to early April. The seed germinates best at 18 to 20 °C, after which the seedlings want bright, cool conditions around 15 °C — a warm windowsill leaves them long and floppy, while a cold frame or unheated greenhouse keeps them sturdy. After about ten weeks they are pencil-thick and go out from mid-May.

When are leeks ready to harvest?

From September, once the shank is roughly as thick as a thumb, and with winter varieties right through to mid-March. Leeks never ripen and go over, they just keep growing slowly, so there is no harvest date you can miss.

Why is my leek running to flower?

It has had a cold trigger — typical of plants started very early, and of leeks that stood through the winter and want to flower in their second year. A woody core then forms inside the shank; the soft leaf sheaths around it stay usable, but lift those plants promptly.

Can leeks be frozen?

Yes, raw and without blanching: slice into rings, wash them well, drain thoroughly and freeze in portions so nothing clumps together. Thawed leek is soft and belongs in soup, a pan or a bake; for salads and dips, reach for fresh shanks instead.