When Should You Transplant Leeks?
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GardenSays
Plant leek transplants outside Apr 14 – Apr 28.
- Transplant outside
- Apr 14 – Apr 28
- Last frost (typ.)
- May 5
- First fall frost
- Oct 5
In Minneapolis, MN, the typical last frost lands around May 5. Garden centers stock transplants well before it's actually safe to plant them. Leeks are cold-hardy, so they can go out Apr 14-Apr 28, even before the frost date.
- This year's transplant window (Apr 14 – Apr 28) has passed — dates shown are for planning next season.
Do this this week
- 1.Passed for this season — plan next spring: start seeds indoors ~Feb 10 – Feb 24, transplant ~Apr 14 – Apr 28
Calculated result · 3 verified sources · Checked 2026-07-18 · How we decide
Why
That leaves roughly 160 days of growing season before the typical first fall frost (Oct 5) — enough for most varieties. In a short-season area, favor early-maturing varieties (check the days-to-maturity on the tag).
- Frost kills tender seedlings outright, and cold soil stunts them even without frost — both dates matter.
- The 50% frost date is a planning midpoint: a late frost is still possible, so keep covers handy for the first two weeks.
When this doesn't apply
- A cold-hardy allium transplanted in early spring, similar timing to onion. UMN gives 'February to seed, transplant early spring' without a precise day count; the -21 to -7 window is our estimate for what 'early spring' means for a hardy allium, consistent with onion's own verified pattern.
- Season extenders (row covers, walls of water, cold frames) let you plant 2-3 weeks earlier than these windows.
- Frost dates are area averages — low spots and valley floors run colder than the local average.
How this was calculated
- 1. Last spring frostMay 5Source guidance
Minneapolis, MN: typical (50% probability) last 32°F frost
- 2. Seed starting windowFeb 10 – Feb 24Calculated result
Leek: start indoors 10-12 weeks before your typical transplant date
- 3. Transplant windowApr 14 – Apr 28Calculated result
Leek is cold-hardy: go out 7-21 days before the last frost, once soil has warmed
- 4. First fall frostOct 5Source guidance
Minneapolis, MN: typical first 32°F frost in fall — the season's endpoint
Data sources
- University of Minnesota Extension — Growing leeks in home gardens — Start seeds indoors and transplant in early spring; February is the optimal time to seed leeks, onions and celery. Most leeks need 120-150 days and at least 8 hours of sun daily; some newer cultivars need as few as 90 days. (checked 2026-07-18)
- NOAA NCEI — 1991-2020 U.S. Climate Normals (freeze date probabilities) (checked 2026-07-15)
- National Gardening Association — frost date lookup (checked 2026-07-15)
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