Alpena, MI frost dates
Last spring frostMay 5median date
First fall frostOct 17median date
Growing season165 daysfrost-free
Hardiness zone5bZone 5b
How Alpena compares
- In 8 years out of 10, the last spring frost in Alpena falls between April 21 and May 21, a 30-day window. The first fall frost falls between September 30 and November 1.
- The median last frost is the same as the Michigan median of May 5.
- Its 165-day growing season is longer than 60% of the 878 Michigan places with a regular frost season (state median 162 days).
- The last frost is 4 days later than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 149 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 21 |
| 50% (median) | May 5 |
| 10% (safe for tender plants) | May 21 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 30 |
| 50% (median) | October 17 |
| 90% (late) | November 1 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Alpena, MI
Alpena, MI frost dates — last frost May 5, first frost Oct 17, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Feb 10 to Feb 24Transplant outside: Apr 7 to Apr 21
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Feb 24 to Mar 10Transplant outside: May 19 to Jun 2
Start indoors: Mar 10 to Mar 24Transplant outside: May 12 to May 26
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Sow outdoors: Apr 7 to May 12Plant for fall: Aug 22 to Sep 19
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 7 to Apr 21Sow outdoors: Apr 7 to Apr 21Plant for fall: Aug 8 to Aug 29
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 14 to Apr 28Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 21 to May 5Plant for fall: Jul 11 to Aug 1
Start indoors: Mar 24 to Apr 7Transplant outside: May 26 to Jun 9Sow outdoors: May 26 to Jun 9
Start indoors: Mar 24 to Apr 7Transplant outside: May 12 to May 26
Sow outdoors: Mar 24 to Apr 14Plant for fall: Jul 25 to Aug 15
Sow outdoors: Mar 24 to Apr 14Plant for fall: Aug 22 to Sep 12
Sow outdoors: Mar 31 to May 12Plant for fall: Sep 5 to Sep 26
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to May 26Sow outdoors: May 12 to May 26Plant for fall: Aug 1 to Aug 15
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26Plant for fall: Aug 8 to Aug 22
Start indoors: Apr 7 to Apr 14Sow outdoors: May 12 to May 26
Start indoors: Apr 7 to Apr 14Transplant outside: May 19 to Jun 2
Sow outdoors: Apr 14 to May 12Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 14 to May 12Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 14 to May 5
Sow outdoors: Apr 21 to May 19Plant for fall: Aug 8 to Aug 22
Sow outdoors: Apr 21 to May 12Plant for fall: Aug 22 to Sep 12
Sow outdoors: May 12 to Jun 2Plant for fall: Aug 1 to Aug 15
Sow outdoors: May 12 to May 26
Transplant outside: May 19 to Jun 9
Plant for fall: Oct 3 to Nov 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alpena, MI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 10 – Feb 24 | Apr 7 – Apr 21 | — | — |
| Peppers | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Eggplant | Feb 24 – Mar 10 | May 19 – Jun 2 | — | — |
| Tomatoes | Mar 10 – Mar 24 | May 12 – May 26 | — | — |
| Lettuce | Mar 10 – Mar 24 | Apr 14 – Apr 28 | Apr 7 – May 12 | Aug 22 – Sep 19 |
| Kale | Mar 10 – Mar 24 | Apr 7 – Apr 21 | Apr 7 – Apr 21 | Aug 8 – Aug 29 |
| Broccoli | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jul 11 – Aug 1 |
| Cabbage | Mar 10 – Mar 24 | Apr 14 – Apr 28 | — | Jul 11 – Aug 1 |
| Cauliflower | Mar 10 – Mar 24 | Apr 21 – May 5 | — | Jul 11 – Aug 1 |
| Okra | Mar 24 – Apr 7 | May 26 – Jun 9 | May 26 – Jun 9 | — |
| Basil | Mar 24 – Apr 7 | May 12 – May 26 | — | — |
| Peas | — | — | Mar 24 – Apr 14 | Jul 25 – Aug 15 |
| Spinach | — | — | Mar 24 – Apr 14 | Aug 22 – Sep 12 |
| Radishes | — | — | Mar 31 – May 12 | Sep 5 – Sep 26 |
| Cucumbers | Apr 7 – Apr 14 | May 19 – May 26 | May 12 – May 26 | Aug 1 – Aug 15 |
| Zucchini & Summer Squash | Apr 7 – Apr 14 | — | May 12 – May 26 | Aug 8 – Aug 22 |
| Winter Squash & Pumpkins | Apr 7 – Apr 14 | — | May 12 – May 26 | — |
| Melons & Watermelon | Apr 7 – Apr 14 | May 19 – Jun 2 | — | — |
| Carrots | — | — | Apr 14 – May 12 | Jul 25 – Aug 8 |
| Beets | — | — | Apr 14 – May 12 | Aug 8 – Aug 22 |
| Potatoes | — | — | Apr 14 – May 5 | — |
| Swiss Chard | — | — | Apr 21 – May 19 | Aug 8 – Aug 22 |
| Cilantro | — | — | Apr 21 – May 12 | Aug 22 – Sep 12 |
| Green Beans | — | — | May 12 – Jun 2 | Aug 1 – Aug 15 |
| Sweet Corn | — | — | May 12 – May 26 | — |
| Sweet Potatoes | — | May 19 – Jun 9 | — | — |
| Garlic | — | — | — | Oct 3 – Nov 7 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Alpena Wwtp, MI weather station, 3 km away (elevation 591 ft (180 m)).
Frost dates near Alpena
- Herron May 17 · Oct 1
- Ossineke May 5 · Oct 17
- Posen May 13 · Oct 3
- Lachine May 17 · Oct 1
- Hubbard Lake May 17 · Oct 1
- Presque Isle May 13 · Oct 3
- Spruce May 8 · Oct 16
- Black River May 8 · Oct 16
- Hillman May 22 · Sep 27
- Hawks May 10 · Oct 14
Frequently asked questions
When is the last frost in Alpena, MI?
The median last spring frost in Alpena, MI is May 5. There is still about a 10% chance of frost after May 21, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alpena, MI?
The median first fall frost is October 17, with about a 10% chance of frost before September 30.
How long is the growing season in Alpena, MI?
About 165 days between the median last spring frost and first fall frost.
What planting zone is Alpena, MI?
Alpena, MI is in USDA hardiness zone 5b.