Rochester Hills, Michigan: planting zone & frost dates
Rochester Hills is in USDA plant hardiness zone 6a, where the average coldest winter night reaches -10 to -5°F (-23.3 to -20.6°C). The typical last spring frost is around May 2 and the first fall frost around Oct 16.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 12 | Oct 7 |
| Typical planning date (30% risk) | May 2 | Oct 16 |
| Median (50%) | Apr 26 | Oct 22 |
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 PONTIAC WWTP, MI (USC00206658), 5.2 mi (8.3 km) from the city center and 85 ft higher than the city center (+26 m). Record used for the 1991–2020 normals: 15 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Rochester Hills
All 3 ZIP codes covering Rochester Hills are in zone 6a.
Vegetable planting calendar for Rochester Hills
Dates are counted from the 30%-risk frost dates above (last frost May 2, first frost Oct 16). 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 7 – Sep 4 |
| Green Beans | — | — | May 9 – Jun 13 | Jul 24 – Aug 7 |
| Sweet Corn | — | — | May 9 – Jun 6 | — |
| Zucchini & Summer Squash | Apr 4 – Apr 11 | May 9 – May 23 | May 9 – May 30 | Jul 24 – Aug 7 |
| Cucumber | Apr 4 – Apr 11 | May 16 – May 23 | May 9 – May 30 | Jul 24 – Aug 7 |
| Carrot | — | — | Apr 11 – May 16 | Jul 24 – Aug 7 |
| 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 21 – Sep 18 |
| Kale | Mar 7 – Mar 21 | Apr 4 – Apr 25 | Apr 4 – Apr 25 | Aug 7 – Sep 4 |
| Broccoli | Mar 7 – Mar 21 | Apr 18 – May 9 | — | Jul 24 – Aug 7 |
| Peas | — | — | Mar 21 – Apr 11 | Aug 7 – Aug 21 |
| Eggplant | Feb 21 – Mar 7 | May 16 – May 30 | — | — |
| Cabbage | Mar 7 – Mar 21 | Apr 4 – Apr 18 | — | Jul 24 – Aug 7 |
| Radish | — | — | Mar 28 – May 16 | Sep 4 – Oct 2 |
| Strawberry | — | Apr 4 – Apr 25 | — | — |
| Beets | — | — | Apr 11 – May 23 | Aug 7 – Aug 21 |
Nearby cities in Michigan
- Troy — zone 6b, last frost May 2, first frost Oct 16
- Sterling Heights — zone 6b, last frost May 5, first frost Oct 18
- Southfield — zone 6b, last frost May 8, first frost Oct 10
- Warren — zone 6b, last frost Apr 27, first frost Oct 24
- Farmington Hills — zone 6a, last frost May 8, first frost Oct 10
- Detroit — zone 6b, last frost May 2, first frost Oct 20
More: all Michigan cities · other zone 6a cities: Chicago, IL, Denver, CO, Milwaukee, WI, Colorado Springs, CO, Omaha, NE, Aurora, CO, Lincoln, NE, Fort Wayne, IN
Rochester Hills gardening questions
When is the last frost in Rochester Hills, MI?
Plan around May 2. At NOAA's Pontiac Wwtp, MI station, 5.2 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 26, and after May 12 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 16. 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 Rochester Hills, 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 167 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 Rochester Hills?
About 177 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 158 days, and in 1 year in 10 it runs 195 days or more. In fall there is a 10% chance of frost by Oct 7 and a 30% chance by Oct 16. That ranks 5th longest of 15 Michigan cities on this site.
When should I plant a fall garden in Rochester Hills?
Count back from the first fall frost (Oct 16): transplant broccoli Jul 24 – Aug 7; sow kale Aug 7 – Sep 4; sow lettuce Aug 7 – Sep 4; sow radishes Sep 4 – Oct 2. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 4. How the math works: succession and fall planting.
Did Rochester Hills's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Rochester Hills is zone 6a 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 Rochester Hills compare with Sterling Heights, MI?
Rochester Hills is zone 6a and Sterling Heights is zone 6b. The typical last spring frost in Rochester Hills (May 2) comes about the same time as in Sterling Heights, MI (May 5), 9 miles away, and the first fall frost is Oct 16 versus Oct 18. Rochester Hills sits about 190 ft higher, which explains part of the gap. The two cities use different NOAA stations.