USDA zone 6b in Michigan
USDA plant hardiness zone 6b covers 27 locations across Michigan (average annual extreme minimum −5 to 0 °F): Arcadia, MI, Benzonia, MI, Carleton, MI, Detroit, MI, Detroit, MI, Eastlake, MI, and 21 more. Average last spring frost across this group ranges April 17 (Paw Paw Lake) to May 22 (Glen Arbor), and growing seasons run 136–201 days (Whitehall to Paw Paw Lake) — 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 Sterling Heights, this group's median-season location.
- USDA zone
- 6b−5 to 0 °F
- Last frost range
- Apr 17–May 22avg, 32°F
- First frost range
- Oct 4–Nov 5avg, 32°F
- Growing season range
- 136–201days
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) |
|---|---|---|---|---|---|
| Arcadia | — | Beulah 7ssw | May 7 | Oct 20 | 163 |
| Benzonia | Elberta, Honor | Frankfort 2ne | May 2 | Oct 26 | 175 |
| Carleton | — | Carleton 2w | Apr 27 | Oct 20 | 176 |
| Detroit | Livonia, Southfield, Dearborn, Westland, Dearborn Heights, Allen Park, +5 more | Dearborn | May 1 | Oct 15 | 166 |
| Detroit | Sterling Heights, Warren, Troy, Royal Oak, Madison Heights, Oak Park, +3 more | Detroit City Ap | Apr 21 | Oct 31 | 190 |
| Eastlake | Onekama, Stronach, Filer | Manistee 3se | May 14 | Oct 12 | 151 |
| Fair Plain | Lake Michigan Beach, Bridgman, Millburg, New Troy, Stevensville, Coloma, +1 more | Benton Harbor Ap | May 5 | Oct 15 | 161 |
| Glen Arbor | Empire, Maple | Maple City 1e | May 22 | Oct 9 | 140 |
| Greilickville | Suttons Bay, Lake Leelanau, Cedar | Nw Michigan Rsch Farm | Apr 30 | Nov 1 | 182 |
| Holland | Grand Haven, Beechwood, Douglas, Saugatuck, Fennville | Holland Tulip City Ap | Apr 28 | Oct 21 | 175 |
| Livonia | Farmington Hills, Southfield, Bingham Farms | Farmington | May 1 | Oct 17 | 165 |
| Ludington | — | Ludington 4 Se | May 17 | Oct 7 | 144 |
| Luna Pier | West Monroe | Monroe | Apr 23 | Oct 23 | 182 |
| Norton Shores | Muskegon, Grand Haven, Ferrysburg, North Muskegon, Fruitport | Muskegon Co Ap | Apr 30 | Oct 19 | 170 |
| Omena | Northport | Northport 2w | May 9 | Oct 26 | 169 |
| Paw Paw Lake | South Haven, Breedsville | S Haven | Apr 17 | Nov 5 | 201 |
| Pentwater | Mears | Hart 3 Wsw | May 12 | Oct 10 | 151 |
| Plymouth | — | Ann Arbor U Of Mich | May 3 | Oct 13 | 160 |
| Port Huron | — | Port Huron | Apr 19 | Nov 3 | 196 |
| Romulus | Taylor, Westland, Trenton, Southgate, Flat Rock, Inkster, +4 more | Detroit Metro Ap | Apr 20 | Oct 27 | 188 |
| Shorewood-Tower Hills-Harbert | New Buffalo | Laporte | Apr 19 | Oct 27 | 191 |
| South Rockwood | Luna Pier, West Monroe, Estral Beach | Newport 4sse | Apr 27 | Oct 22 | 177 |
| St. Clair Shores | Roseville, Eastpointe, Grosse Pointe Woods, Harper Woods, Grosse Pointe Park, Village of Grosse Pointe Shores | Grosse Pointe Farms | Apr 29 | Oct 22 | 176 |
| Sterling Heights * | St. Clair Shores, Pearl Beach, New Baltimore, Fraser, Mount Clemens, New Haven, +2 more | Mt Clemens Ang Base | Apr 30 | Oct 24 | 174 |
| Temperance | Luna Pier | Dundee | Apr 27 | Oct 21 | 176 |
| Troy | Birmingham | Pontiac Oakland Co Intl Ap | Apr 29 | Oct 20 | 172 |
| Whitehall | — | Montague 4 Nw | May 19 | Oct 4 | 136 |
* Sterling Heights 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 (Sterling Heights, representative)
Computed from Sterling Heights's average frost dates — the median-season location in this Michiganzone 6b 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 5 – Mar 19 | May 7 – May 14 | Jul 6 – Jul 26 | — | matures comfortably |
| Pepper | Very tender | Feb 19 – Mar 5 | May 14 – May 21 | Jul 13 – Aug 12 | — | matures comfortably |
| Cucumber | Tender | Apr 2 – Apr 9 | May 7 – May 14 | Jun 26 – Jul 16 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 7 – May 14 | Jun 21 – Jul 6 | — | matures comfortably |
| Bush bean | Tender | — | May 7 – May 14 | Jun 26 – Jul 6 | Aug 25 – Sep 4 | matures comfortably |
| Sweet corn | Tender | — | Apr 30 – May 14 | Jun 29 – Jul 29 | — | matures comfortably |
| Basil | Very tender | Mar 19 – Apr 2 | May 7 – May 14 | Jun 6 – Jun 21 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 19 – Apr 2 | Apr 2 – Apr 16 | May 17 – Jun 1 | Aug 11 – Aug 26 | matures comfortably |
| Pea | Hardy | — | Mar 19 – Apr 2 | May 13 – May 28 | Aug 1 – Aug 16 | matures comfortably |
| Spinach | Hardy | — | Mar 19 – Apr 2 | Apr 28 – May 8 | Aug 21 – Aug 31 | matures comfortably |
| Carrot | Half-hardy | — | Apr 9 – Apr 16 | Jun 8 – Jun 28 | Jul 22 – Aug 11 | matures comfortably |
| Broccoli | Half-hardy | Mar 5 – Mar 19 | Apr 2 – Apr 16 | May 27 – Jun 16 | Jul 27 – Aug 16 | matures comfortably |
Which crops fit this growing season
Using Sterling Heights's own 174-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 (Sterling Heights)
From NOAA's 1991–2020 Climate Normals at station USW00014804. 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 | May 11 | May 28 | Oct 9 | Oct 24 | 150 |
| 32°F (freeze) | Apr 30 | May 15 | Oct 24 | Nov 3 | 174 |
| 28°F | Apr 18 | May 3 | Nov 3 | Nov 15 | 196 |
| 24°F | Apr 5 | Apr 20 | Nov 13 | Nov 28 | 220 |
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 27 locations is 2,754; Sterling Heights's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,703 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,766 | cool-season crops (brassicas, greens) |
Hardiness zone 6b in Michigan
Zone 6b means an average annual extreme minimum winter temperature of about −5 to 0 °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, 5a, 5b, 6a, 7a.
Explore zone 6b in other states at zone 6b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 6b mean in Michigan?
- Zone 6b means an average annual extreme minimum winter temperature of −5 to 0 °F — the standard USDA measure of which perennials survive winter. 27 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 6b is the growing season longest?
- Paw Paw Lake runs the longest season on this page at about 201 days; Whitehall is shortest at about 136 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 6b?
- Using Sterling Heights's frost dates (this page's median-season location): start seeds indoors about Mar 5 – Mar 19, then transplant outside about May 7 – May 14. 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 6b 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 27 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.