Growing Leeks in your Garden – Vegetable GardeningGrowing Leeks in your Garden – Vegetable Gardening
“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 flavor that doesn’t overpower other ingredients. Although considered a gourmet vegetable, leeks are hardy, pest-free and easy to grow.
How to Growing Start leeks
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 millimeters 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 centimeters high, thin them to one per cell (four centimeters 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-centimeter-deep trench, then position the seedlings 10 to 15 centimeters 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-centimeter-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 centimeters 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.
Diseases and Pests
While leeks are susceptible to the same diseases and pests as onions, they’re far more resistant, and gardeners seldom have any problems.
These pests pierce the leaves and suck out plant juices, causing silver spots. Serious infestations result in stunted, bleached foliage that dies. Don’t plant leeks near fields of alfalfa or grain. Spray with insecticidal soap; remove weeds and debris around the garden to prevent thrips from overwintering.
Adults lay eggs at the bases of young plants. The white maggots burrow into the underground stems, causing the plants to wilt, turn yellow and possibly rot. Mulch immediately after planting to prevent the flies from laying eggs. Destroy infected plants and do good fall cleanup.
Plant leeks in well-drained soil and always practice a four-year crop rotation (including all types of onions). Don’t water late in the day. Destroy infected plants and do good fall cleanup.
Harvesting and storage
Growing both summer and winter varieties of leeks will extend your harvest season. Summer cultivars grow quickly, usually producing a crop in August. However, they don’t store well, won’t overwinter and need to be dug up before a heavy frost. Winter ones are larger, produce in the fall, are hardier and will survive fairly heavy frosts, and, if protected, may overwinter in parts of Canada. They also store better.
Dig up leeks with a garden fork, being careful not to damage the white shaft of the plant. When using within a week, cut off the root end and leaves, and store unwashed in a plastic bag in the refrigerator—they’ll take up less room this way. The leaves can be coarsely chopped and frozen to add to winter soup stocks.
If winter temperatures remain above –12°C, hardy varieties can be left in the garden. In colder climates, leave leeks in during the first light frosts, then dig them up before the first killing frost. Cut off the roots just below the base of the shaft and trim the leaves to eight centimeters. When stored at 0°C and 95 percent humidity, leeks will keep for two to three months.
Note: Days to maturity are from transplanting dates.
‘Arena’ (110 days) Hardy, long, white shafts; suitable for overwintering and storage
‘Blue Solaise’ (105 days) Large, very hardy; good for storing and overwintering
‘Giant Musselburgh’ (105 days) Heirloom variety; thick, succulent stems; good for overwintering and storage
‘Jolant’ (100 days) Excellent-quality summer type
‘King Richard’ (75 days) Fast-growing summer type; tall, slender and tender; can be sown close together to produce baby leeks to use as a garnish
‘Sheriff’ (110 days) Hardy; suitable for storing and overwintering
‘Siegfried Frost’ (125 days) Large, hardy; good for storing and overwintering
Never buy seeds again
The enthusiastic gardener can propagate next season’s crop by overwintering plants.
No protection is required on the West Coast, but elsewhere, you’ll have to mulch the leeks deeply with straw, hay or leaves. In areas with severe winters (Zone 5 or below), before the first heavy frost, dig them out, leaving a large ball of soil around their roots. Stored at 0°C with high humidity, they should survive to be replanted the next season.
Leeks are biennials, and overwintered plants will send up stalks that produce huge, round, lavender blooms the following spring. Left on the plant, the flowers set seed that can be collected and, when thoroughly dry, stored in a cool, dry place for planting next year. Different varieties of leeks will freely cross-pollinate, producing hybrids unlike either of their parents. If saving seeds, only grow one variety if you want it to stay true to type.
Alternatively, you could leave the plants in the ground after flowering. In the fall, dig them up and gather the small bulblets that have formed around their bases; plant these the following spring. The bulblets produce plants identical to their parents, so more than one variety can be grown without worrying about crossing.