When to plant Leek
Computed from land-grant Extension planting-window rules (cited below), localized to real ZIP-level median frost dates, not a single national guess. These are national-generic rules by hardiness class; individual state Extension offices layer their own regional adjustment on top (earlier in the Deep South, later in the Upper Midwest). Enter your ZIP for your own dates, or read the four representative locations below.
Planting windows and crop timing here are computed from USDA/NOAA climate data and the university extension sources cited below, not a site visit or soil test. Treat this as a starting point: local conditions vary, and a local nursery or extension office can advise on your exact site. See our full Disclaimer.
Representative timing, by climate band
When to plant Leek in four US climates
Each column is the most nursery-dense location in our directory within that USDA zone band, computed from that location's own real median frost dates, not a made-up example.
| Stage |
Zones 1-5 (cold winters)
Fort Plain, NY |
Zones 6-7 (temperate)
McMinnville, TN |
Zones 8-9 (warm)
Apopka, FL |
Zones 10-13 (hot, frost rare or absent)
Loxahatchee, FL |
|---|---|---|---|---|
| Start seed indoors | Not available | Not available | Not available | – |
| Direct-sow outside | Not available | Not available | Not available | – |
| Transplant outside | Mar 25–Apr 22 | Feb 24–Mar 24 | Jan 13–Feb 10 | – |
| Fall planting | Not available | Not available | Not available | – |
| Expected harvest | May 14–Aug 20 | Apr 15–Jul 22 | Mar 4–Jun 10 | – |
Zones 10-13 (hot, frost rare or absent) (Loxahatchee, FL): Frost is rare here (about 359 frost-free days a year); most years see little or no hard freeze. This is a semi hardy crop. In climates like this one, hardy and semi-hardy crops typically go in during the cooler months (fall through late winter), not on a frost-relative schedule.
Leek transplants two to six weeks before your last frost. Colorado State University Extension classifies leek semi-hardy, with a window of zero to two weeks before frost and a 40°F minimum soil temperature (Fact Sheet 7.212); Purdue Extension's Table 1 (HO-186-W) instead lists leek as hardy, with a four-to-six-week-before-frost window, a real disagreement in classification, not just in the number. This page keeps Colorado State's semi-hardy label, since it carries the fuller numeric data for this crop, but widens the window to include Purdue's earlier hardy-tier range rather than picking one silently.
Days to maturity run 50 to 120 days on this page: Colorado State's 120 days and Clemson Cooperative Extension's roughly 120 days from seed to maturity (in its Onion, Leek, Shallot, & Garlic factsheet) agree closely and corroborate each other, while NC State Extension's 50-to-80-day figure sits well below both and may be measuring from transplant rather than from seed. The full range is reported here rather than dropping NC State's lower figure, with that likely explanation flagged.
Because the two anchor sources disagree on how hardy leek really is, a cold-winter climate is better served treating Colorado State's later, zero-to-two-week window as the more cautious choice; a mild-winter climate has more room to use Purdue's earlier range without much added risk.
Leek is slow enough, at up to 120 days, that nurseries commonly sell it as a transplant rather than leaving the full run to seed; seed is available for anyone willing to start it themselves well ahead of the two-to-six-week window above.
Frost hardiness
Semi-hardy. Tolerates light frost. Best planted close to the last frost date.
Minimum soil temperature
40°F
For direct sowing/germination, where an Extension source stated it.
Days to maturity
50–120
Sourcing notes
Real disagreement: CSU places leek semi-hardy (0-2wk before frost, min soil 40F); PURDUE's Table 1 instead lists leek Hardy (4-6wk before frost). Kept CSU's semi_hardy label (it has the fuller numeric data) but widened the window to include PURDUE's earlier hardy range, flagged. DTM: CSU (120) and Clemson ("about 120 days from seed to maturity") agree closely and corroborate each other; NCSU's 50-80-day figure is a clear outlier, possibly measuring from transplant rather than seed - flagged, full range reported.
Related crops
Growing zones for this crop
Nurseries near these locations
Sources
- Clemson Cooperative Extension Home & Garden Information Center, Onion, Leek, Shallot, & Garlic (accessed 2026-08-04)
- Colorado State University Extension, Vegetable Planting Guide (Fact Sheet 7.212) (accessed 2026-08-04)
- NC State Extension, Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs (AG-756-01) (accessed 2026-08-04)
- Purdue Extension (Dept. of Horticulture and Landscape Architecture), Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-08-04)
- Virginia Cooperative Extension, Virginia Tech and Virginia State University, Virginia's Home Garden Vegetable Planting Guide (Pub. 426-331) (accessed 2026-08-04)