When to plant in Port Washington, WI
USDA Zone 5bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Port Washington, Wisconsin — all computed from Port Washington's nearest NOAA weather station.
Zone 5b means Port Washington sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
The average first fall frost in Port Washington is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
PORT WASHINGTON · 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 Port Washington’s own odds, recorded at PORT WASHINGTON.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 25 | May 10 | Apr 26 | Sep 26 | Oct 10 | Oct 24 |
| 32°F | May 14 | Apr 27 | Apr 11 | Oct 6 | Oct 22 | Nov 4 |
| 28°F | Apr 30 | Apr 13 | Mar 31 | Oct 19 | Nov 2 | Nov 17 |
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 Port Washington, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 10 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.
Port Washington planting FAQ
When is the last spring frost in Port Washington, WI?
Port Washington's average last spring frost falls near April 27 — 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 Port Washington, WI?
The first fall frost in Port Washington typically arrives around October 22 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Port Washington in?
Port Washington is in USDA hardiness zone 5b. In zone 5b, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Port Washington?
There are roughly 178 frost-free days in Port Washington (a moderate growing season), running from the average last frost around April 27 to the first fall frost near October 22.
When should I plant tomatoes in Port Washington?
In Port Washington, start tomato seeds indoors around March 2–March 16, then transplant seedlings outdoors around May 4 once the danger of frost has passed.
Never miss a window in Port Washington
An email when it’s time to start seeds, transplant, and sow — timed to Port Washington’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Grafton · 9 km
- Cedarburg · 13 km
- Mequon · 22 km
- West Bend · 24 km
- Brown Deer · 25 km
- Germantown · 26 km
- Glendale · 29 km
- Whitefish Bay · 30 km
Frost dates recorded at PORT WASHINGTON, 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 Port Washington, WI — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00476764. Retrieved from https://blissgarden.com/wisconsin/port-washington.