When to plant in Hermantown, MN
USDA Zone 4bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Hermantown, Minnesota — all computed from Hermantown's nearest NOAA weather station.
Zone 4b is cold — in Hermantown, most perennials must be fully hardy, and your frost dates set a tight window for tender annual vegetables.
Frost probability
DULUTH NWS · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Hermantown’s own odds, recorded at DULUTH NWS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 17 | Jun 1 | May 16 | Sep 8 | Sep 22 | Oct 4 |
| 32°F | Jun 3 | May 18 | May 2 | Sep 19 | Oct 1 | Oct 14 |
| 28°F | May 21 | May 4 | Apr 22 | Sep 29 | Oct 12 | Oct 27 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Hermantown, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 12 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Hermantown planting FAQ
When is the last spring frost in Hermantown, MN?
On average, the last spring frost in Hermantown is around May 18 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Hermantown, MN?
Expect Hermantown's first fall frost near October 1 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Hermantown in?
Hermantown is in USDA hardiness zone 4b. In zone 4b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Hermantown?
There are roughly 136 frost-free days in Hermantown (a short growing season), running from the average last frost around May 18 to the first fall frost near October 1.
When should I plant tomatoes in Hermantown?
In Hermantown, start tomato seeds indoors around March 23–April 6, then transplant seedlings outdoors around May 25 once the danger of frost has passed.
Never miss a window in Hermantown
An email when it’s time to start seeds, transplant, and sow — timed to Hermantown’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Duluth · 9 km
- Superior · 17 km
- Cloquet · 22 km
- Hibbing · 85 km
- Grand Rapids · 109 km
- North Branch · 154 km
- Cambridge · 158 km
- Brainerd · 158 km
Frost dates recorded at DULUTH NWS, 4 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Hermantown, MN — Frost Dates & Zone 4b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00212250. Retrieved from https://blissgarden.com/minnesota/hermantown.