How long do leeks take to grow?

From indoor-started transplants, most varieties mature in 100–130 days after transplanting to the garden. Starting indoors in late January or February for late April transplanting typically means harvest from late August through December. Early varieties shorten this to 90–100 days; winter storage types extend to 130+ days. Per Penn State Extension, "leeks occupy garden space for most of the growing season" — plan planting schedules accordingly.

How do I blanch leeks?

Blanching (excluding light from the lower shank) produces the white, tender portion that most recipes specify. Trench or hill soil against developing shanks as they grow — the soil-covered portion stays white and mild-flavored while the green, exposed portion is somewhat tougher and more pungent. The trench method, dibble method, or simple draw-hoe hilling all achieve the same result. Per University of Minnesota Extension, "gradual hilling as plants grow" is the simplest technique for most gardeners.

Can I direct sow leeks?

Yes, but it requires early sowing and produces smaller transplant-sized plants that are then set out, which eliminates much of the advantage. Direct sowing is more practical in mild-winter zones (8–10) where a fall sowing produces harvest-ready plants by late spring. In zones 4–7, indoor starting is strongly recommended to gain the 10–12 weeks of growth needed before outdoor planting.

How do I store leeks?

Refrigerate unwashed leeks in a plastic bag for up to 2 weeks. For longer storage, leave them in the ground in zones 6–8 (they are more cold-hardy than most other vegetables) and harvest as needed through early winter. For root cellar storage, trim leaves to 4 inches, leave roots intact, and store in moist sand at 32–40°F for up to 3 months. Blanch and freeze blanched sections for 6–12 months of frozen storage.

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Leek Care: Long-Season Alliums for Winter Soups

Growing Allium ampeloprasum var. porrum from seed to harvest — the long season timeline, trench-and-hill technique for blanching the shank, and variety selection by days to maturity.

By Thomas Joseph Published 2026-06-11 Updated 2026-06-13 Reviewed by Thomas Joseph 7 min read

Large leeks with blue-green leaves and white blanched shanks growing in a fall garden — Photo: Unsplash

USDA hardiness and when leeks grow

Allium ampeloprasum var. porrum is a cool-season biennial grown as an annual in all zones 3–9. Unlike most cool-season crops, leeks occupy garden space for most of the year — transplanted in spring, they are harvested in fall and early winter. Per Penn State Extension, leeks are "among the hardiest vegetables grown," surviving temperatures down to 0°F in some late-maturing varieties. In zones 6–8, leeks left in the ground with light mulch can be harvested through December or January.

In zones 3–5, earlier-maturing varieties (95–100 days to maturity) are preferable; in zones 6–9, longer-season varieties (120–130 days) with thicker shanks are feasible. Per University of Minnesota Extension, late-season varieties like 'Bulgarian Giant' and 'American Flag' overwinter best in northern zones and produce the thickest shanks.

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Leek Care: Long-Season Alliums for Winter Soups

USDA hardiness and when leeks grow