When to plant in Ann Arbor, MI
USDA Zone 6aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Ann Arbor, Michigan — all computed from Ann Arbor's nearest NOAA weather station.
Zone 6a means Ann Arbor sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
ANN ARBOR SE · 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 Ann Arbor’s own odds, recorded at ANN ARBOR SE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 29 | May 15 | May 1 | Sep 18 | Oct 1 | Oct 12 |
| 32°F | May 20 | May 5 | Apr 21 | Sep 28 | Oct 10 | Oct 24 |
| 28°F | May 11 | Apr 24 | Apr 10 | Oct 7 | Oct 23 | Nov 6 |
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 Ann Arbor, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 6 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.
Ann Arbor planting FAQ
When is the last spring frost in Ann Arbor, MI?
Plan for the last spring frost in Ann Arbor around May 5 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Ann Arbor, MI?
The first fall frost in Ann Arbor typically arrives around October 10 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Ann Arbor in?
Ann Arbor 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 Ann Arbor?
There are roughly 158 frost-free days in Ann Arbor (a moderate growing season), running from the average last frost around May 5 to the first fall frost near October 10.
When should I plant tomatoes in Ann Arbor?
In Ann Arbor, start tomato seeds indoors around March 10–March 24, then transplant seedlings outdoors around May 12 once the danger of frost has passed.
Never miss a window in Ann Arbor
An email when it’s time to start seeds, transplant, and sow — timed to Ann Arbor’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at ANN ARBOR SE, 5 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 Ann Arbor, MI — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00200228. Retrieved from https://blissgarden.com/michigan/ann-arbor.