How to Grow Leek
Allium porrum
Leeks are hardy alliums prized for their mild, onion-like flavor that intensifies when cooked. Gardeners grow them for their sturdy stalks used in soups, stews, and sautés. These cool-season crops thrive in cooler weather and tolerate light frost well.
📷 Wikimedia CommonsStarting Leek: indoors or direct sow?
🏠 Start indoors 4 weeks before your last spring frost, then move the seedlings outside.
Transplant hardened seedlings outdoors once the risk of hard frost has passed, spacing them carefully to ensure proper bulb formation.
Soil, care & harvest
Prepare loose, fertile soil with a pH between 6.0 and 7.5. As a cool-season crop, sow seeds indoors or direct-sow outdoors 2 to 6 weeks before the last spring frost. Press seeds lightly into the soil at a depth of about 1/4 inch. Expect germination in 7 to 10 days once moisture is consistent.
Space seedlings 6 to 8 inches apart after thinning, as mature plants need room for bulb development. Keep soil consistently moist but not waterlogged to encourage straight growth. Apply a light layer of mulch around the base to retain moisture and suppress weeds. Feed lightly with balanced fertilizer if growth seems slow.
Watch for onion flies, which can be deterred by row covers, and leaf spot diseases prevented by good air circulation. Harvest leeks when they reach your desired size, typically within 16 to 25 days after emergence for microgreens or longer for full stalks. Cut at soil level or pull gently if roots are tender.
When to Plant Leek
Planting windows vary by USDA hardiness zone. Look up yours by ZIP code.
| Zone | Start Indoors | Direct Sow | Harvest |
|---|---|---|---|
| Zone 1 | January – December | — | January – December |
| Zone 2 | January – December | — | January – December |
| Zone 3 | January – December | — | January – December |
| Zone 4 | January – December | — | January – December |
| Zone 5 | January – December | — | January – December |
| Zone 6 | January – December | — | January – December |
| Zone 7 | January – December | — | January – December |
| Zone 8 | January – December | — | January – December |
| Zone 9 | January – December | — | January – December |
| Zone 10 | January – December | — | January – December |
| Zone 11 | January – December | — | January – December |
| Zone 12 | January – December | — | January – December |
| Zone 13 | January – December | — | January – December |
Companion Plants for Leek
✓ Good companions
Leeks repel cabbage worms and moths, protecting brassica crops
Carrots help break up soil for leek roots and leeks repel carrot fly
Similar growing requirements and leeks help repel celery leaf spot and aphids
Shallow-rooted lettuce doesn't compete with leeks and benefits from their pest-repelling properties
Repel nematodes and aphids while attracting beneficial insects
Both alliums complement each other and provide mutual pest protection against aphids and thrips
Quick-growing spinach can be harvested before leeks mature, maximizing space efficiency
Leeks deter tomato hornworms and aphids while tomatoes provide natural shade
✗ Keep away from
Legumes can stunt allium growth through nitrogen competition and root interference
May inhibit leek growth due to allelopathic compounds and nutrient competition
Strong aromatic compounds can inhibit growth of alliums including leeks
Nutrition Facts
Per 100g serving (USDA FoodData Central)
