When to plant in Alpena, MI
USDA Zone 5bEverything below — frost dates, hardiness zone, and what to plant when in Alpena, Michigan — is derived from the closest NOAA station with complete climate normals.
In zone 5b, Alpena gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
ALPENA 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 Alpena’s own odds, recorded at ALPENA WWTP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 30 | May 17 | May 2 | Sep 20 | Oct 4 | Oct 19 |
| 32°F | May 21 | May 5 | Apr 21 | Sep 30 | Oct 17 | Nov 1 |
| 28°F | May 13 | Apr 23 | Apr 7 | Oct 15 | Oct 31 | 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 Alpena, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 15 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.
Alpena planting FAQ
When is the last spring frost in Alpena, MI?
Alpena's average last spring frost falls near May 5 — 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 Alpena, MI?
In Alpena, the first 32°F freeze of fall lands around October 17 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Alpena in?
Alpena 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 Alpena?
Alpena has about 165 frost-free days — a moderate growing season — between the average last spring frost (May 5) and first fall frost (October 17).
When should I plant tomatoes in Alpena?
For Alpena, sow tomatoes indoors about March 10–March 24 and move the seedlings out around May 12, after the last spring frost.
Never miss a window in Alpena
An email when it’s time to start seeds, transplant, and sow — timed to Alpena’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Bay City · 169 km
- Sault Ste. Marie · 172 km
- Midland · 173 km
- Traverse City · 174 km
- Cadillac · 182 km
- Saginaw · 189 km
- Mount Pleasant · 196 km
- Flint · 229 km
Frost dates recorded at ALPENA 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 Alpena, MI — Frost Dates & Zone 5b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00014814. Retrieved from https://blissgarden.com/michigan/alpena.