Leeks: Easier Than Their Reputation Suggests

Leeks have an unfair reputation for being complicated. These delicious, mild, non-bulbing onion relatives are easy to start from seed and, with simple techniques, produce long, white stalks perfect for classic leek and potato soup, braised dishes, casseroles, and risottos.

About This Plant

Leek cultivars fall into two categories: less hardy short-season types (planted spring, harvested summer/early fall) and hardier long-season types (100+ days, planted spring in the North, late summer/fall in the South, harvested through winter in mild climates or until ground freezes in the North). To develop the long white stalks used in cooking, plants must be blanched by covering stalks with soil as they grow.

Site Selection

Choose a site with full sun and well-drained soil. Loosen soil to 12–15 inches and mix in a 2- to 4-inch layer of compost.

Planting Instructions

Start seeds indoors 8–10 weeks before the last expected spring frost. Sow ½ inch deep in pots at least 6 inches deep, thinning to 1 inch apart when seedlings reach 3 inches. Cool conditions (60–65°F) are best. Harden off and transplant as soon as soil can be worked.

Trench method: Dig a 6-inch-deep trench, set seedlings 6 inches apart in the bottom. As plants grow, gradually fill the trench, blanching stalks. Hole method: Plant seedlings 8–10 inches apart in a wide row by poking 6-inch-deep holes with a rake handle, dropping seedlings in, and watering—soil washes in to cover roots. Holes fill naturally as plants grow. Hill additional soil for longer white stalks.

For overwintering in southern areas, sow seeds 8–12 weeks before the first expected fall frost.

Care

Leeks need steady nitrogen and plenty of water. Feed monthly with organic fertilizer (e.g., fish emulsion). Keep well-weeded—leeks suffer from weed competition. Cover at planting with a floating row cover sealed with soil to exclude onion maggot flies. Silvery or rusty streaks on leaves indicate thrips; hose off with a strong water stream.

Harvesting

Begin harvesting as soon as stalks are usable; slender young stalks are tasty braised. For largest stalks, let short-season leeks grow until just before fall frosts. Loosen soil with a fork before pulling to avoid breakage. Leave hardy long-season leeks until just before ground freezes or through winter in the South. Mulch with straw in fall to extend harvest by preventing soil freezing. Overwintered leeks can be harvested in early spring before they bolt; after bolting, they become stringy and tough.

Store harvested leeks wrapped in plastic in the refrigerator for up to 2 weeks; trim green tops to a few inches for easier storage.