Southfield, Michigan: planting zone & frost dates
Southfield 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 8 and the first fall frost around Oct 10.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 16 | Oct 1 |
| Typical planning date (30% risk) | May 8 | Oct 10 |
| Median (50%) | May 1 | Oct 17 |
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 FARMINGTON, MI (USC00202691), 5.3 mi (8.5 km) from the city center and 49 ft higher than the city center (+15 m). Record used for the 1991–2020 normals: 16 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Southfield
All 4 ZIP codes covering Southfield are in zone 6b.
Vegetable planting calendar for Southfield
Dates are counted from the 30%-risk frost dates above (last frost May 8, first frost Oct 10). 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 13 – Mar 27 | May 15 – May 29 | — | — |
| Pepper | Feb 27 – Mar 13 | May 22 – Jun 5 | — | — |
| Lettuce | Mar 27 – Apr 10 | Apr 24 – May 15 | Apr 10 – May 22 | Aug 1 – Aug 29 |
| Green Beans | — | — | May 15 – Jun 19 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 15 – Jun 12 | — |
| Zucchini & Summer Squash | Apr 10 – Apr 17 | May 15 – May 29 | May 15 – Jun 5 | Jul 18 – Aug 1 |
| Cucumber | Apr 10 – Apr 17 | May 22 – May 29 | May 15 – Jun 5 | Jul 18 – Aug 1 |
| Carrot | — | — | Apr 17 – May 22 | Jul 18 – Aug 1 |
| Onion | Feb 13 – Feb 27 | Apr 10 – Apr 24 | — | — |
| Potato | — | Apr 10 – May 1 | — | — |
| Basil | Mar 27 – Apr 10 | May 22 – Jun 5 | May 22 – Jun 12 | — |
| Spinach | — | — | Mar 27 – Apr 24 | Aug 15 – Sep 12 |
| Kale | Mar 13 – Mar 27 | Apr 10 – May 1 | Apr 10 – May 1 | Aug 1 – Aug 29 |
| Broccoli | Mar 13 – Mar 27 | Apr 24 – May 15 | — | Jul 18 – Aug 1 |
| Peas | — | — | Mar 27 – Apr 17 | Aug 1 – Aug 15 |
| Eggplant | Feb 27 – Mar 13 | May 22 – Jun 5 | — | — |
| Cabbage | Mar 13 – Mar 27 | Apr 10 – Apr 24 | — | Jul 18 – Aug 1 |
| Radish | — | — | Apr 3 – May 22 | Aug 29 – Sep 26 |
| Strawberry | — | Apr 10 – May 1 | — | — |
| Beets | — | — | Apr 17 – May 29 | Aug 1 – Aug 15 |
Nearby cities in Michigan
- Farmington Hills — zone 6a, last frost May 8, first frost Oct 10
- Livonia — zone 6b, last frost May 8, first frost Oct 10
- Troy — zone 6b, last frost May 2, first frost Oct 16
- Dearborn — zone 6b, last frost May 8, first frost Oct 9
- Detroit — zone 6b, last frost May 2, first frost Oct 20
- Westland — zone 6b, last frost Apr 28, first frost Oct 22
More: all Michigan cities · other zone 6b cities: Columbus, OH, Indianapolis, IN, Boston, MA, Detroit, MI, Kansas City, MO, Cincinnati, OH, Pittsburgh, PA, Buffalo, NY
Southfield gardening questions
When is the last frost in Southfield, MI?
Plan around May 8. At NOAA's Farmington, MI station, 5.3 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 May 1, and after May 16 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 22. The last frost is fairly predictable here: only 27 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Southfield, MI?
Start seeds indoors Mar 13 – Mar 27 and set transplants outside May 15 – May 29, once nights stay above 50°F and the soil is near 60°F. That leaves 155 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 Southfield?
About 165 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 146 days, and in 1 year in 10 it runs 183 days or more. In fall there is a 10% chance of frost by Oct 1 and a 30% chance by Oct 10. That ranks 12th longest of 15 Michigan cities on this site.
When should I plant a fall garden in Southfield?
Count back from the first fall frost (Oct 10): transplant broccoli Jul 18 – Aug 1; sow kale Aug 1 – Aug 29; sow lettuce Aug 1 – Aug 29; sow radishes Aug 29 – Sep 26. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 27. How the math works: succession and fall planting.
Did Southfield's hardiness zone change on the 2023 map?
Yes. Most of Southfield was zone 6a on the 2012 map and is zone 6b on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Southfield compare with Troy, MI?
Both are in zone 6b. The typical last spring frost in Southfield (May 8) comes about 6 days later than in Troy, MI (May 2), 10 miles away, and the first fall frost is Oct 10 versus Oct 16. The two cities use different NOAA stations.