USDA zone 5a in Michigan
USDA plant hardiness zone 5a covers 45 locations across Michigan (average annual extreme minimum −20 to −15 °F): Alba, MI, Atlanta, MI, Baraga, MI, Boyne Falls, MI, Brimley, MI, Chassell, MI, and 39 more. Average last spring frost across this group ranges May 5 (Mackinac Island) to June 7 (Lewiston), and growing seasons run 95–167 days (Lewiston to Mackinac Island) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Michigan location's own frost dates; the printable planting calendar uses Boyne Falls, this group's median-season location.
- USDA zone
- 5a−20 to −15 °F
- Last frost range
- May 5–Jun 7avg, 32°F
- First frost range
- Sep 14–Oct 20avg, 32°F
- Growing season range
- 95–167days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Alba | — | Gaylord | May 25 | Sep 26 | 125 |
| Atlanta | Hillman | Atlanta | May 22 | Sep 27 | 127 |
| Baraga | Pelkie | Alberta Ford For Ctr | May 23 | Oct 1 | 128 |
| Boyne Falls * | — | Boyne Falls | May 23 | Oct 3 | 133 |
| Brimley | Newberry, Naubinway | Trout Lake 1sw | May 21 | Oct 1 | 131 |
| Chassell | Trimountain, Painesdale | Hancock Houghton Co Ap | May 17 | Oct 1 | 138 |
| Chatham | K. I. Sawyer | Chatham Exp Farm 2 | May 30 | Sep 27 | 119 |
| Cheboygan | — | Cheboygan | May 11 | Oct 11 | 152 |
| Daggett | Stephenson | Stephenson 5wsw | May 22 | Sep 27 | 126 |
| Escanaba | Gladstone, Carney, Rapid River, Powers, Rock | Cornell 5se | May 19 | Oct 1 | 133 |
| Evart | Reed, Farwell, Baldwin, Hersey, Paris | Big Rapids Wtp | May 13 | Oct 2 | 142 |
| Gaylord | — | Gaylord Otsego Co Ap | May 22 | Sep 30 | 130 |
| Grand Marais | — | Grand Marais 2 E | May 27 | Oct 10 | 138 |
| Grayling | — | Grayling | May 23 | Sep 27 | 124 |
| Greenland | — | Ontonagon 6 Se | May 27 | Oct 1 | 127 |
| Gwinn | Palmer | Marquette | May 22 | Sep 29 | 129 |
| Harrison | — | Gladwin | May 9 | Oct 4 | 148 |
| Houghton Lake | St. Helen, Prudenville, Roscommon | Houghton Lk Roscommon Ap | May 19 | Sep 23 | 125 |
| Houghton Lake | Falmouth | Houghton Lake 6 Wsw | May 30 | Sep 15 | 106 |
| Hubbard Lake | Alpena, Hillman | Alpena Co Rgnl Ap | May 17 | Oct 1 | 136 |
| Indian River | Pellston, Alanson, Levering | Pellston Rgnl Ap | May 31 | Sep 18 | 108 |
| K. I. Sawyer | — | Ki Sawyer Wwtp | May 13 | Oct 2 | 141 |
| Kincheloe | — | Sault Ste Marie | May 22 | Oct 4 | 136 |
| Le Roy | Luther, Boon, Wedgewood, Tustin | Cadillac | May 19 | Oct 1 | 135 |
| Lewiston | Vanderbilt | Vanderbilt 11ene | Jun 7 | Sep 14 | 95 |
| Lupton | Rose | Lupton 1s | May 21 | Sep 29 | 129 |
| Mackinac Island | De Tour | Detour Village | May 5 | Oct 20 | 167 |
| Mackinac Island | St. Ignace | Moran | May 23 | Sep 30 | 130 |
| Manistee Lake | Mancelona | Kalkaska | May 24 | Oct 1 | 128 |
| Manistique | Newberry | Manistique Wwtp | May 9 | Oct 10 | 154 |
| Marion | McBain, Lake | Lake City Exp Farm | May 22 | Sep 26 | 125 |
| Millersburg | — | Rogers City | May 10 | Oct 14 | 154 |
| Mio | Lewiston | Mio Hydro Plt | May 19 | Oct 2 | 136 |
| Munising | — | Munising | May 16 | Oct 14 | 148 |
| Naubinway | — | Engadine Mdot | May 26 | Sep 30 | 127 |
| Newberry | — | Whitefish Pt | May 23 | Oct 15 | 144 |
| Newberry | Naubinway | Newberry Correctional Facility | May 21 | Oct 5 | 135 |
| Norway | Hermansville | Iron Mtn-kingsford Wwtp | May 17 | Oct 1 | 135 |
| Oden | — | Petoskey | May 6 | Oct 20 | 166 |
| Ontonagon | — | Bergland Dam | May 26 | Sep 27 | 123 |
| Pelkie | — | Baraga 7nw | May 25 | Sep 23 | 119 |
| Sand Lake | Hubbard Lake, Lupton, Whittemore | Hale Loud Dam | May 16 | Oct 5 | 143 |
| Skanee | Zeba | Herman | May 31 | Sep 22 | 115 |
| Tower | — | Onaway 4n | May 22 | Oct 2 | 135 |
| West Branch | Prescott | W Branch 3se | May 15 | Oct 4 | 143 |
* Boyne Falls is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Boyne Falls, representative)
Computed from Boyne Falls's average frost dates — the median-season location in this Michiganzone 5a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 28 – Apr 11 | May 30 – Jun 6 | Jul 29 – Aug 18 | — | matures comfortably |
| Pepper | Very tender | Mar 14 – Mar 28 | Jun 6 – Jun 13 | Aug 5 – Sep 4 | — | matures comfortably |
| Cucumber | Tender | Apr 25 – May 2 | May 30 – Jun 6 | Jul 19 – Aug 8 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 30 – Jun 6 | Jul 14 – Jul 29 | — | matures comfortably |
| Bush bean | Tender | — | May 30 – Jun 6 | Jul 19 – Jul 29 | Aug 4 – Aug 14 | matures comfortably |
| Sweet corn | Tender | — | May 23 – Jun 6 | Jul 22 – Aug 21 | — | matures comfortably |
| Basil | Very tender | Apr 11 – Apr 25 | May 30 – Jun 6 | Jun 29 – Jul 14 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 11 – Apr 25 | Apr 25 – May 9 | Jun 9 – Jun 24 | Jul 21 – Aug 5 | matures comfortably |
| Pea | Hardy | — | Apr 11 – Apr 25 | Jun 5 – Jun 20 | Jul 11 – Jul 26 | matures comfortably |
| Spinach | Hardy | — | Apr 11 – Apr 25 | May 21 – May 31 | Jul 31 – Aug 10 | matures comfortably |
| Carrot | Half-hardy | — | May 2 – May 9 | Jul 1 – Jul 21 | Jul 1 – Jul 21 | matures comfortably |
| Broccoli | Half-hardy | Mar 28 – Apr 11 | Apr 25 – May 9 | Jun 19 – Jul 9 | Jul 6 – Jul 26 | matures comfortably |
Which crops fit this growing season
Using Boyne Falls's own 133-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Boyne Falls)
From NOAA's 1991–2020 Climate Normals at station USC00200925. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Jun 2 | Jun 21 | Sep 19 | Oct 5 | 110 |
| 32°F (freeze) | May 23 | Jun 6 | Oct 3 | Oct 19 | 133 |
| 28°F | May 10 | May 27 | Oct 16 | Nov 2 | 160 |
| 24°F | Apr 27 | May 15 | Nov 1 | Nov 16 | 185 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 45 locations is 1,935; Boyne Falls's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,556 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,478 | cool-season crops (brassicas, greens) |
Hardiness zone 5a in Michigan
Zone 5a means an average annual extreme minimum winter temperature of about −20 to −15 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Michigan spans 7 hardiness zones in this dataset — see all Michigan locations for the full range, including zones4a, 4b, 5b, 6a, 6b, 7a.
Explore zone 5a in other states at zone 5a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 5a mean in Michigan?
- Zone 5a means an average annual extreme minimum winter temperature of −20 to −15 °F — the standard USDA measure of which perennials survive winter. 45 locations in Michigan fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Michigan's zone 5a is the growing season longest?
- Mackinac Island runs the longest season on this page at about 167 days; Lewiston is shortest at about 95 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Michigan's zone 5a?
- Using Boyne Falls's frost dates (this page's median-season location): start seeds indoors about Mar 28 – Apr 11, then transplant outside about May 30 – Jun 6. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Michigan's zone 5a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 45 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.