When to plant in Grafton, WI
USDA Zone 6aEverything below — frost dates, hardiness zone, and what to plant when in Grafton, Wisconsin — is derived from the closest NOAA station with complete climate normals.
Zone 6a means Grafton sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
GRAFTON 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 Grafton’s own odds, recorded at GRAFTON WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 23 | May 5 | Apr 20 | Sep 27 | Oct 11 | Oct 26 |
| 32°F | May 9 | Apr 23 | Apr 10 | Oct 8 | Oct 24 | Nov 5 |
| 28°F | Apr 24 | Apr 11 | Mar 31 | Oct 21 | Nov 2 | Nov 15 |
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 Grafton, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 11 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.
Grafton planting FAQ
When is the last spring frost in Grafton, WI?
On average, the last spring frost in Grafton is around April 23 (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 Grafton, WI?
Expect Grafton's first fall frost near October 24 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Grafton in?
Grafton is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Grafton?
There are roughly 184 frost-free days in Grafton (a moderate growing season), running from the average last frost around April 23 to the first fall frost near October 24.
When should I plant tomatoes in Grafton?
In Grafton, start tomato seeds indoors around February 26–March 12, then transplant seedlings outdoors around April 30 once the danger of frost has passed.
Never miss a window in Grafton
An email when it’s time to start seeds, transplant, and sow — timed to Grafton’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Cedarburg · 4 km
- Port Washington · 9 km
- Mequon · 13 km
- Brown Deer · 16 km
- Germantown · 17 km
- Glendale · 22 km
- West Bend · 22 km
- Menomonee Falls · 23 km
Frost dates recorded at GRAFTON WWTP, 2 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 Grafton, WI — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00473198. Retrieved from https://blissgarden.com/wisconsin/grafton.