Warren, Michigan: planting zone & frost dates
Warren 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 Apr 27 and the first fall frost around Oct 24.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 6 | Oct 17 |
| Typical planning date (30% risk) | Apr 27 | Oct 24 |
| Median (50%) | Apr 21 | Oct 31 |
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 DETROIT CITY AP, MI (USW00014822), 5.8 mi (9.4 km) from the city center and 3 ft higher than the city center (+1 m). Record used for the 1991–2020 normals: 29 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Warren
All 5 ZIP codes covering Warren are in zone 6b.
Vegetable planting calendar for Warren
Dates are counted from the 30%-risk frost dates above (last frost Apr 27, first frost Oct 24). 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 2 – Mar 16 | May 4 – May 18 | — | — |
| Pepper | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Lettuce | Mar 16 – Mar 30 | Apr 13 – May 4 | Mar 30 – May 11 | Aug 15 – Sep 12 |
| Green Beans | — | — | May 4 – Jun 8 | Aug 1 – Aug 15 |
| Sweet Corn | — | — | May 4 – Jun 1 | — |
| Zucchini & Summer Squash | Mar 30 – Apr 6 | May 4 – May 18 | May 4 – May 25 | Aug 1 – Aug 15 |
| Cucumber | Mar 30 – Apr 6 | May 11 – May 18 | May 4 – May 25 | Aug 1 – Aug 15 |
| Carrot | — | — | Apr 6 – May 11 | Aug 1 – Aug 15 |
| Onion | Feb 2 – Feb 16 | Mar 30 – Apr 13 | — | — |
| Potato | — | Mar 30 – Apr 20 | — | — |
| Basil | Mar 16 – Mar 30 | May 11 – May 25 | May 11 – Jun 1 | — |
| Spinach | — | — | Mar 16 – Apr 13 | Aug 29 – Sep 26 |
| Kale | Mar 2 – Mar 16 | Mar 30 – Apr 20 | Mar 30 – Apr 20 | Aug 15 – Sep 12 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – May 4 | — | Aug 1 – Aug 15 |
| Peas | — | — | Mar 16 – Apr 6 | Aug 15 – Aug 29 |
| Eggplant | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Cabbage | Mar 2 – Mar 16 | Mar 30 – Apr 13 | — | Aug 1 – Aug 15 |
| Radish | — | — | Mar 23 – May 11 | Sep 12 – Oct 10 |
| Strawberry | — | Mar 30 – Apr 20 | — | — |
| Beets | — | — | Apr 6 – May 18 | Aug 15 – Aug 29 |
Nearby cities in Michigan
- Sterling Heights — zone 6b, last frost May 5, first frost Oct 18
- Detroit — zone 6b, last frost May 2, first frost Oct 20
- Troy — zone 6b, last frost May 2, first frost Oct 16
- Rochester Hills — zone 6a, last frost May 2, first frost Oct 16
- Southfield — zone 6b, last frost May 8, first frost Oct 10
- Dearborn — zone 6b, last frost May 8, first frost Oct 9
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
Warren gardening questions
When is the last frost in Warren, MI?
Plan around Apr 27. At NOAA's Detroit City Airport, MI station, 5.8 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 21, and after May 6 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 8. 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 Warren, MI?
Start seeds indoors Mar 2 – Mar 16 and set transplants outside May 4 – May 18, once nights stay above 50°F and the soil is near 60°F. That leaves 180 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 Warren?
About 190 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 171 days, and in 1 year in 10 it runs 208 days or more. In fall there is a 10% chance of frost by Oct 17 and a 30% chance by Oct 24. That is the longest of the 15 Michigan cities on this site.
When should I plant a fall garden in Warren?
Count back from the first fall frost (Oct 24): transplant broccoli Aug 1 – Aug 15; sow kale Aug 15 – Sep 12; sow lettuce Aug 15 – Sep 12; sow radishes Sep 12 – Oct 10. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 9. How the math works: succession and fall planting.
Did Warren's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Warren 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 Warren compare with Sterling Heights, MI?
Both are in zone 6b. The typical last spring frost in Warren (Apr 27) comes about 8 days earlier than in Sterling Heights, MI (May 5), 6 miles away, and the first fall frost is Oct 24 versus Oct 18. The two cities use different NOAA stations.