When to plant in Hartford, WI
USDA Zone 5aHartford, Wisconsin frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
In zone 5a, Hartford gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
HARTFORD WWTP · 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 Hartford’s own odds, recorded at HARTFORD WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 2 | May 20 | May 5 | Sep 12 | Sep 25 | Oct 6 |
| 32°F | May 24 | May 8 | Apr 24 | Sep 20 | Oct 3 | Oct 16 |
| 28°F | May 12 | Apr 27 | Apr 11 | Sep 30 | Oct 15 | Oct 30 |
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 Hartford, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 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.
Hartford planting FAQ
When is the last spring frost in Hartford, WI?
Hartford's average last spring frost falls near May 8 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Hartford, WI?
Expect Hartford's first fall frost near October 3 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Hartford in?
Hartford is in USDA hardiness zone 5a. In zone 5a, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Hartford?
Hartford has about 148 frost-free days — a short growing season — between the average last spring frost (May 8) and first fall frost (October 3).
When should I plant tomatoes in Hartford?
For Hartford, sow tomatoes indoors about March 13–March 27 and move the seedlings out around May 15, after the last spring frost.
Never miss a window in Hartford
An email when it’s time to start seeds, transplant, and sow — timed to Hartford’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Richfield · 15 km
- West Bend · 19 km
- Lisbon · 21 km
- Germantown · 23 km
- Sussex · 24 km
- Oconomowoc · 26 km
- Menomonee Falls · 28 km
- Pewaukee · 30 km
Frost dates recorded at HARTFORD WWTP, 3 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 Hartford, WI — Frost Dates & Zone 5a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00473453. Retrieved from https://blissgarden.com/wisconsin/hartford.