Minnesota planting calendar

When to plant leeks in Minnesota — sow, transplant & harvest dates

Minnesota is mostly USDA zone 4b (range 3a-5a). Dates below are derived from leeks's frost tolerance and Minnesota's frost window — not generic national averages.

Leeks planting timetable for Minnesota

Stage	When in Minnesota	Anchor
Start seeds indoors	early March (March 6)	10 weeks before the last frost (mid-May)
Transplant outside	mid-April (April 17)	28 days before the last frost (mid-May)
First harvest (estimate)	mid-August (August 15)	~120 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Minnesota's climate shifts the leeks dates

Minnesota's last spring frost averages mid-May and first fall frost late September, which sets the whole planting clock. Minnesota is one of the coldest states in the contiguous US. Cold-hardy varieties and a compressed season define gardening here. Sow early — leeks bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Leeks are among the hardiest alliums — established plants tolerate temperatures as low as -10 °C, making them a reliable overwintering crop in zones 5–9. Start seeds indoors 10–12 weeks before last frost, transplanting pencil-thick seedlings into 15 cm (6-inch) deep holes or trenches to blanch the stems; backfill gradually as plants grow. Early-season varieties mature in around 90 days; late-season types take up to 150 days and deliver the best cold-hardiness for autumn and winter harvest.

Frost-risk note

Don't plant before mid-May — a hard freeze can still set young plants back. In the far north near International Falls (zone 3a) the safe date runs a week or two later.

Regional variation within Minnesota

the far north near International Falls (zone 3a) runs roughly 1-2 weeks behind the state average; the Twin Cities metro and far south (zone 5a) can plant 1-2 weeks earlier.

Minneapolis — USDA zone 5a
Saint Paul — USDA zone 5a
Duluth — USDA zone 4b
Rochester — USDA zone 4b

What else to plant in Minnesota around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 7-25 °C (45-77 °F).
Spacing: 6 inches (15 cm) between plants.
Days to harvest: ~120 days from planting out.

Frequently asked questions

When is the best time to plant leeks in Minnesota?

In Minnesota (mostly USDA zone 4b), sow leeks indoors around early March, transplant outdoors mid-April (before the last frost, mid-May), and harvest from mid-August. Leeks are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

What USDA zone is Minnesota?

Most of Minnesota sits in USDA hardiness zone 4b, with the state spanning roughly 3a-5a from the far north near International Falls (zone 3a) to the Twin Cities metro and far south (zone 5a). The last spring frost averages mid-May and the first fall frost late September.

Can you grow leeks in Minnesota?

Yes. Minnesota's dominant zone 4b supports leeks — the key is timing. Leeks are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

Does the planting date change across Minnesota?

the far north near International Falls (zone 3a) runs roughly 1-2 weeks behind the state average; the Twin Cities metro and far south (zone 5a) can plant 1-2 weeks earlier.

What else can I plant in Minnesota around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.