How to Grow Leeks
Allium ampeloprasum
Patient, cold-hardy alliums with a sweet, mild onion flavor and long season.
By the Plants by Zone Editorial Team · Reviewed June 1, 2026
About leeks
Leeks are slow-growing alliums prized for their tender, mild white shanks. They demand a long season and a little fuss — blanching the stems for length — but reward it with hardiness that lets many varieties stand in the garden through hard frosts. They are a cornerstone of the cool-season kitchen garden.
When to plant and harvest leeks
Timing is relative to your frost dates. Find your USDA zone for exact dates, or browse the month-by-month calendars.
Start seeds indoors
8–10 weeks before last frost
Transplant outdoors
Around last frost
Direct sow
Possible in mild zones, early spring
Harvest
Late summer through winter
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How to grow leeks step by step
- 1
Start seeds indoors early — leeks are slow and need a head start.
- 2
When seedlings are pencil-thick, transplant into 6-inch-deep holes and let them fill in with water rather than backfilling.
- 3
Hill or mound soil around the stems as they grow to blanch a longer white shank.
- 4
Keep evenly moist and feed mid-season; leeks are heavy feeders.
- 5
Mulch heavily in fall — many varieties overwinter and can be dug as needed.
- 6
Harvest once shanks are an inch or more thick.
Common problems growing leeks
⚠ Short, thin white shanks
Blanch by planting in deep holes and hilling soil up the stems as they grow.
⚠ Onion thrips or leek moth
Use row cover, rotate alliums yearly, and remove debris where pests overwinter.
⚠ Slow, stalled growth
Leeks are heavy feeders — enrich the bed with compost and side-dress with nitrogen mid-season.
✗ Keep away from
🧺 Harvesting leeks
Dig (don’t pull) leeks with a fork once the shanks are usably thick, loosening the soil first since the roots run deep. In cold zones, mulch heavily and harvest through winter as needed — flavor sweetens after frost.
Leeks: frequently asked questions
When should you plant leeks?＋
In most regions you start seeds indoors 8–10 weeks before last frost, then transplant around last frost — or direct sow possible in mild zones, early spring. Timing is relative to your last frost, so find your USDA hardiness zone for the exact planting dates where you live.
How do I get long white leek stems?＋
Blanch them: plant seedlings in deep holes and mound soil up around the stems as they grow. The buried portion stays pale and tender.
Can leeks survive winter?＋
Yes — many varieties are very cold-hardy. Mulch heavily and dig them as you need them right through winter in most zones.
Sources & review
Written and maintained by the Plants by Zone Editorial Team. Planting times are based on USDA hardiness zones and NOAA frost-date normals, with care guidance drawn from Cooperative Extension sources. Last reviewed June 1, 2026.
USDA Plant Hardiness Zone MapNOAA U.S. climate normalsCooperative Extension
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