Planting and Growing Leeks in Cold-Climate Gardens

Leeks are mild, sweet, and silky when cooked. They add gentle onion flavor without sharp heat. The crop loves cool weather and steady moisture, which fits northern gardens. Hardy varieties stand through frost and even light snow. With early indoor starts, careful transplanting, and hilling for white shanks, you can grow leeks in cold climates and harvest from late summer into winter.

Leek Varieties Suitable for Cold Climates

  • King Richard. Early, long shanks for summer harvest.
  • Lexton. Midseason, thick stems and good uniformity.
  • Tadorna. Hardy plants for fall and early winter pulls.
  • Bandit. Very cold-hardy with short, thick shanks for winter.
  • Porbella. Mid to late and reliable in cool, wet weather.
  • Bleu de Solaise. Heirloom with strong winter color and hardiness.

Soil & Site Considerations for Leeks

  • Choose full sun and shelter from strong winds.
  • Use deep, fertile, well-drained loam with plenty of compost.
  • Aim for soil pH 6.2–7.0 for healthy roots and balanced nutrients.
  • Keep soil loose to 20–25 cm (8–10 in) for easy planting and blanching.
  • Use raised beds on heavy soils to prevent waterlogging.

Planting and Spacing Leeks in Cold Regions

  • Start seeds indoors 8–10 weeks before the last spring frost.
  • Trim seedling tops to 7–8 cm (3 in) to thicken stems before transplanting.
  • Transplant when pencil-thick and soil is 7–10 °C (45–50 °F).
  • Drop seedlings into 15–20 cm (6–8 in) deep dibble holes and water to settle soil.
  • Space 10–15 cm (4–6 in) apart in rows 30–45 cm (12–18 in) apart.
  • Hill soil or mulch up the stems through the season for long white shanks.

Companion Plants for Leeks

  • Grow with carrots, beets, celery, and lettuce to share space well.
  • Plant thyme, dill, or chamomile nearby to bring helpful insects.
  • Avoid close planting with beans and peas to reduce growth checks.
  • Keep beds weed-free because leeks are slow to shade soil.

Watering & Fertilizing Leeks

  • Give 3–4 cm (1¼–1½ in) of water per week for steady growth.
  • Mulch 5–8 cm (2–3 in) to keep moisture and suppress weeds.
  • Feed with compost at planting and side-dress with nitrogen midseason.
  • Stop high nitrogen late so plants harden before hard frost.

Extending the Season for Leeks

  • Use fleece after transplanting to speed early growth and reduce wind stress.
  • Hill soil and add straw in fall to protect shanks for late harvests.
  • Cover with low tunnels or cold frames to dig through early winter.
  • In very cold zones, lift late leeks and heel them into a cool shed or tunnel.

Leek Crop Calendar

  • High-Latitude. Start indoors in March to April. Transplant in late May to June. Harvest August to November, longer with cover.
  • Boreal. Start indoors in February to March. Transplant in late May. Harvest August to December with mulch.
  • Cool-Temperate. Start indoors in February. Transplant in April to May. Harvest July to December and overwinter hardy types.

Mistakes to Avoid When Growing Leeks

  • Planting shallow and failing to blanch stems.
  • Letting weeds compete and slow early growth.
  • Overfertilizing late and leaving soft, winter-tender plants.
  • Watering irregularly and getting tough, pithy stems.
  • Burying leaves with soil instead of hilling gradually and keeping soil out of sheaths.

Sustainability Checklist

  • Rotate alliums for at least three years.
  • Use drip or soaker hoses to save water and keep foliage dry.
  • Compost clean leek tops and use trimmings as path mulch.
  • Grow flowers nearby for beneficial insects and pollinator support.