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Leeks are a non-bulbing, cool season onion-relative with leaves that grow in a tight cluster up to several feet high. They are milder tasting than onions, and have a distinctive flavor that adds zest to soups and stews, and enhances stuffing, gratins, and casseroles. They also add a nice flavor when sautéed with other vegetables.

The white portion of the stem is used in cooking, just as with scallions.

WHEN TO SOW

SUN OR PART SHADE

SEED SPACING

ROW SPACING

PLANTING DEPTH

SPACE AFTER THINNING

DAYS TO GERMINATE

DAYS TO MATURITY

8-10 weeks before last frost

Full sun or partial shade

1 inch

10-12 inches

½ inch

6 inches

5-7

120

Soil and Fertilizing

It’s best to have your soil tested before planting, so you know what nutrients and pH adjustments may be needed to support your crop. For a thorough soil test, consult your local county extension office.

Leeks prefer a well-drained soil, rich in organic matter, with a slightly acidic pH of 6.0-6.8. Composting can help prepare the soil for leek cultivation. They require a minimum soil temperature of at least 40˚ F to mature.

Planting

Leeks can be direct-seeded or transplanted. Start your seeds indoors about 8-10 weeks before the last frost. Then transplant the seedlings into the garden two weeks before last frost, 4-6″ apart, when the plants are at least 8″ tall and as thick as a pencil. Leeks thrive in raised beds.

Plant them in an area where onions have not been grown in the past three years, as they can pick up pests and diseases onions leave behind.

To prepare the seedling for transplanting, cut off half the green leafy top and don’t bend the roots. Afterward, mulch the plants to conserve soil moisture and deter weeds. Hill the soil or mulch around the stems to blanch them. The stems are blanched (kept white and edible) when they are      under the soil away from the sun; if exposed to the sun, they’ll turn green and inedible.

Watering

Leeks are shallow rooted, so you must keep them well-watered and protected from weeds. Mulch will help keep moisture in and weeds out. One inch of water per week should be sufficient.

Harvesting / Storage

Leeks are mature when the stalks are about 1” in diameter. This takes about 120 days from seed.

Loosen the soil before pulling up the leeks so they don’t break off. You can let the hardy long-season leeks remain in the garden until just before the ground freezes or through the winter in warmer climates.

Harvested leeks can stay wrapped in plastic in the refrigerator for up to 2 weeks; cut off all but a few inches of the green tops so they are easy to store.

 

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For soil testing or other questions specific to your growing climate, please contact your local county extension agent.

Visit http://www.almanac.com/content/cooperative-extension-services to find the office nearest you.