Sault Ste. Marie, MI planting zone & frost dates
Sault Ste. Marie is in USDA hardiness zone 5a. The last spring frost usually comes around May 9 and the first fall frost around October 11, for a growing season of about 151 days.
Planting calendar for Sault Ste. Marie
Dates are counted from the average last spring frost (May 9) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Mar 14 – Mar 28 Transplant outdoors: May 16 – May 23 |
| Peppers | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: May 23 – May 30 |
| Eggplant | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: May 23 – May 30 |
| Broccoli | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: Apr 11 – Apr 25 |
| Cabbage | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: Apr 11 – Apr 25 |
| Onions (sets) | Plant outdoors: Apr 11 – Apr 25 |
| Peas | Sow outdoors: Mar 28 – Apr 11 |
| Spinach | Sow outdoors: Mar 28 – Apr 11 |
| Lettuce | Sow outdoors: Apr 11 – Apr 25 |
| Carrots | Sow outdoors: Apr 11 – Apr 25 |
| Potatoes | Plant outdoors: Apr 11 – Apr 25 |
| Beans | Sow outdoors: May 16 – May 23 |
| Sweet corn | Sow outdoors: May 16 – May 23 |
| Cucumbers | Sow outdoors: May 16 – May 23 |
| Squash & zucchini | Sow outdoors: May 16 – May 23 |
| Basil | Start seeds indoors: Mar 28 – Apr 11 Transplant outdoors: May 16 – May 23 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 16 (8 weeks before the average first fall frost on Oct 11).
Useful for zone 5a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 27 | May 9 | May 27 |
| First 32°F frost in fall is before | Oct 26 | Oct 11 | Sep 26 |
How to read it: in spring there is a 10% chance of a frost after May 27, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 26. A hard freeze (28°F) usually ends around April 27.
Nearby cities
- Alpena zone 5b, last frost May 5
- Traverse City zone 6a, last frost May 9
- Cadillac zone 5a, last frost May 19
- Escanaba zone 5a, last frost May 13
- Midland zone 6a, last frost Apr 29
- Mount Pleasant zone 6a, last frost Apr 30
- Bay City zone 6a, last frost Apr 27
- Big Rapids zone 5b, last frost May 13
Questions
What growing zone is Sault Ste. Marie, MI?
Sault Ste. Marie is in USDA Plant Hardiness Zone 5a (average extreme winter low -20°F to -15°F), according to the USDA 2023 map.
When is the last frost in Sault Ste. Marie?
The average last spring frost (32°F) in Sault Ste. Marie is May 9. There is still a 10% chance of frost until May 27.
When can I plant tomatoes in Sault Ste. Marie?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 16 – May 23. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Sault Ste Marie Sanderson Fld, MI (USW00014847), 2.0 km (1.2 mi) from the city center, elevation 220 m, based on 30 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.