Detroit, Michigan: planting zone & frost dates
Detroit is in USDA plant hardiness zone 6b, where the average coldest winter night reaches -5 to 0°F (-20.6 to -17.8°C). The typical last spring frost is around May 2 and the first fall frost around Oct 20.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 11 | Oct 10 |
| Typical planning date (30% risk) | May 2 | Oct 20 |
| Median (50%) | Apr 27 | Oct 25 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station DEARBORN #2, MI (USC00202016), 4.4 mi (7.1 km) from the city center and 33 ft lower than the city center (-10 m). Record used for the 1991–2020 normals: 14 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Detroit
All 30 ZIP codes covering Detroit are in zone 6b.
ZIP codes in Detroit and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 48228 | 6b | 6.4% |
| 48219 | 6b | 6.1% |
| 48234 | 6b | 5.6% |
| 48227 | 6b | 5.4% |
| 48209 | 6b | 4.9% |
| 48213 | 6b | 4.7% |
| 48205 | 6b | 4.6% |
| 48207 | 6b | 4.5% |
| 48235 | 6b | 4.5% |
| 48223 | 6b | 4.4% |
| 48224 | 6b | 4.2% |
| 48238 | 6b | 3.9% |
| 48203 | 6b | 3.8% |
| 48221 | 6b | 3.7% |
| 48204 | 6b | 3.6% |
| 48210 | 6b | 3.6% |
| 48214 | 6b | 3.6% |
| 48211 | 6b | 2.8% |
| 48215 | 6b | 2.8% |
| 48212 | 6b | 2.6% |
| 48202 | 6b | 2.4% |
| 48208 | 6b | 2.3% |
| 48206 | 6b | 2.2% |
| 48217 | 6b | 1.7% |
| 48216 | 6b | 1.6% |
| 48201 | 6b | 1.4% |
| 48239 | 6b | 1.4% |
| 48226 | 6b | 0.9% |
| 48233 | 6b | 0.0% |
| 48243 | 6b | 0.0% |
Vegetable planting calendar for Detroit
Dates are counted from the 30%-risk frost dates above (last frost May 2, first frost Oct 20). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 7 – Mar 21 | May 9 – May 23 | — | — |
| Pepper | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Lettuce | Mar 21 – Apr 4 | Apr 18 – May 9 | Apr 4 – May 16 | Aug 11 – Sep 8 |
| Green Beans | — | — | May 9 – Jun 13 | Jul 28 – Aug 11 |
| Sweet Corn | — | — | May 9 – Jun 6 | — |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | May 9 – May 23 | May 9 – May 30 | Jul 28 – Aug 11 |
| Cucumber | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 30 | Jul 28 – Aug 11 |
| Carrot | — | — | Apr 11 – May 16 | Jul 28 – Aug 11 |
| Onion | Feb 7 – Feb 21 | Apr 4 – Apr 18 | — | — |
| Potato | — | Apr 4 – Apr 25 | — | — |
| Basil | Mar 21 – Apr 4 | May 16 – May 30 | May 16 – Jun 6 | — |
| Spinach | — | — | Mar 21 – Apr 18 | Aug 25 – Sep 22 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 25 | Apr 4 – Apr 25 | Aug 11 – Sep 8 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 9 | — | Jul 28 – Aug 11 |
| Peas | — | — | Mar 21 – Apr 11 | Aug 11 – Aug 25 |
| Eggplant | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Cabbage | Mar 7 – Mar 21 | Apr 4 – Apr 18 | — | Jul 28 – Aug 11 |
| Radish | — | — | Mar 28 – May 16 | Sep 8 – Oct 6 |
| Strawberry | — | Apr 4 – Apr 25 | — | — |
| Beets | — | — | Apr 11 – May 23 | Aug 11 – Aug 25 |
Nearby cities in Michigan
- Dearborn — zone 6b, last frost May 8, first frost Oct 9
- Warren — zone 6b, last frost Apr 27, first frost Oct 24
- Southfield — zone 6b, last frost May 8, first frost Oct 10
- Troy — zone 6b, last frost May 2, first frost Oct 16
- Sterling Heights — zone 6b, last frost May 5, first frost Oct 18
- Livonia — zone 6b, last frost May 8, first frost Oct 10
More: all Michigan cities · other zone 6b cities: Columbus, OH, Indianapolis, IN, Boston, MA, Kansas City, MO, Cincinnati, OH, Pittsburgh, PA, Buffalo, NY, Toledo, OH
Detroit gardening questions
When is the last frost in Detroit, MI?
Plan around May 2. At NOAA's Dearborn #2, MI station, 4.4 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 27, and after May 11 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 15. The 90% and 10% dates are 29 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Detroit, MI?
Start seeds indoors Mar 7 – Mar 21 and set transplants outside May 9 – May 23, once nights stay above 50°F and the soil is near 60°F. That leaves 171 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Detroit?
About 181 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 159 days, and in 1 year in 10 it runs 199 days or more. In fall there is a 10% chance of frost by Oct 10 and a 30% chance by Oct 20. That ranks 3rd longest of 15 Michigan cities on this site.
When should I plant a fall garden in Detroit?
Count back from the first fall frost (Oct 20): transplant broccoli Jul 28 – Aug 11; sow kale Aug 11 – Sep 8; sow lettuce Aug 11 – Sep 8; sow radishes Sep 8 – Oct 6. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 6. How the math works: succession and fall planting.
Did Detroit's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Detroit is zone 6b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does Detroit compare with Dearborn, MI?
Both are in zone 6b. The typical last spring frost in Detroit (May 2) comes about 6 days earlier than in Dearborn, MI (May 8), 7 miles away, and the first fall frost is Oct 20 versus Oct 9. The two cities use different NOAA stations.