“Onions are adored, and leeks are gods,” declared the Roman poet Juvenal. It was probably the Romans who brought leeks to the U.K., where they flourished, becoming an ingredient of the Scots’ traditional cock-a-leekie soup and the national symbol of Wales. Legend has it that on the eve of a great battle, Welsh soldiers were ordered to wear leeks on their helmets to distinguish themselves from their enemy. The Welsh won the battle, and leeks have been worn on St. David’s Day—and at rugby games—ever since.
Leeks (Allium ampeloprasum) are a close relative of onions, garlic and chives, and share some of the same health benefits—lowering cholesterol and protecting against cancer. They are the mildest of the allium family; the tender part of the bulb (the white and light green parts) has a delicate onion flavour that doesn’t overpower other ingredients. Although considered a gourmet vegetable, leeks are hardy, pest-free and easy to grow.
Start leeks indoors 10 to 12 weeks before the last spring frost. Seeds can be planted in either flats or cell packs filled with seed-starting mixture; those grown in cell packs tend to produce larger transplants, which will grow into the best leeks. Sow seeds six millimetres deep, three per cell; keep at 18 to 21°C. Once they germinate (seven to 10 days), place the seedlings under a grow light or in a south-facing window in a room kept at a cool temperature.
Keep the plants well watered and feed with half-strength organic fertilizer every two weeks. When the seedlings are 2.5 centimetres high, thin them to one per cell (four centimetres apart in flats). As soon as the danger of heavy frost is past, harden them off by gradually exposing them to cool temperatures and direct sunlight. After that, they’ll survive light frosts.
Plant the seedlings in fertile, well-drained soil in full sun. Leeks are heavy feeders, so first prepare the area by digging in lots of compost or composted manure. The goal is to maximize the length of the white edible portion of the stem. This is accomplished by “blanching” the stems: Dig a 10-centimetre-deep trench, then position the seedlings 10 to 15 centimetres apart, depending on the variety, up to the first leaf notch, which will be deeper than they’ve been growing. Or plant them in individual, 10-centimetre-deep holes. Keep them well watered but not soggy until they’re established.
As the leeks grow, gradually fill in the trench or holes with soil. Once filled, start hilling up the soil around the plants until another 18 to 20 centimetres of the stem is covered. In areas with hot summers, mulch with straw or hay rather than hilling up with soil. This is cleaner and will help prevent the bulbs from rotting.
Once a month, side-dress with compost or organic fertilizer; just scratch it into the surface of the soil to avoid damaging the leeks’ shallow roots. Or, feed with compost tea, made by soaking a bag of compost in a pail of water overnight. Keep the bed well weeded and well watered.