Flat Rock, MI frost dates
Last spring frostApr 27median date
First fall frostOct 20median date
Growing season176 daysfrost-free
Hardiness zone6bZone 6b
How Flat Rock compares
- In 8 years out of 10, the last spring frost in Flat Rock falls between April 12 and May 13, a 31-day window. The first fall frost falls between October 4 and November 2.
- The median last frost is 8 days earlier than the Michigan median of May 5.
- Its 176-day growing season is longer than 85% of the 878 Michigan places with a regular frost season (state median 162 days).
- The last frost is 5 days later than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 130 nights a year at or below 32°F.
- Compared with Taylor, MI, 14 km away, the last frost here is 7 days later than there and the growing season is 14 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 12 |
| 50% (median) | April 27 |
| 10% (safe for tender plants) | May 13 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 4 |
| 50% (median) | October 20 |
| 90% (late) | November 2 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Flat Rock, MI
Flat Rock, MI frost dates — last frost Apr 27, first frost Oct 20, zone 6b. whenisthelastfrost.com
Crop
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Start indoors: Feb 2 to Feb 16Transplant outside: Mar 30 to Apr 13
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Mar 2 to Mar 16Transplant outside: May 4 to May 18
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Sow outdoors: Mar 30 to May 4Plant for fall: Aug 25 to Sep 22
Start indoors: Mar 2 to Mar 16Transplant outside: Mar 30 to Apr 13Sow outdoors: Mar 30 to Apr 13Plant for fall: Aug 11 to Sep 1
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 16 to Mar 30Transplant outside: May 18 to Jun 1Sow outdoors: May 18 to Jun 1
Start indoors: Mar 16 to Mar 30Transplant outside: May 4 to May 18
Sow outdoors: Mar 16 to Apr 6Plant for fall: Jul 28 to Aug 18
Sow outdoors: Mar 16 to Apr 6Plant for fall: Aug 25 to Sep 15
Sow outdoors: Mar 23 to May 4Plant for fall: Sep 8 to Sep 29
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 18Sow outdoors: May 4 to May 18Plant for fall: Aug 4 to Aug 18
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18Plant for fall: Aug 11 to Aug 25
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 25
Sow outdoors: Apr 6 to May 4Plant for fall: Jul 28 to Aug 11
Sow outdoors: Apr 6 to May 4Plant for fall: Aug 11 to Aug 25
Sow outdoors: Apr 6 to Apr 27
Sow outdoors: Apr 13 to May 11Plant for fall: Aug 11 to Aug 25
Sow outdoors: Apr 13 to May 4Plant for fall: Aug 25 to Sep 15
Sow outdoors: May 4 to May 25Plant for fall: Aug 4 to Aug 18
Sow outdoors: May 4 to May 18
Transplant outside: May 11 to Jun 1
Plant for fall: Oct 6 to Nov 10
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Flat Rock, MI
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 2 – Feb 16 | Mar 30 – Apr 13 | — | — |
| Peppers | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Eggplant | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Tomatoes | Mar 2 – Mar 16 | May 4 – May 18 | — | — |
| Lettuce | Mar 2 – Mar 16 | Apr 6 – Apr 20 | Mar 30 – May 4 | Aug 25 – Sep 22 |
| Kale | Mar 2 – Mar 16 | Mar 30 – Apr 13 | Mar 30 – Apr 13 | Aug 11 – Sep 1 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 14 – Aug 4 |
| Cabbage | Mar 2 – Mar 16 | Apr 6 – Apr 20 | — | Jul 14 – Aug 4 |
| Cauliflower | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 14 – Aug 4 |
| Okra | Mar 16 – Mar 30 | May 18 – Jun 1 | May 18 – Jun 1 | — |
| Basil | Mar 16 – Mar 30 | May 4 – May 18 | — | — |
| Peas | — | — | Mar 16 – Apr 6 | Jul 28 – Aug 18 |
| Spinach | — | — | Mar 16 – Apr 6 | Aug 25 – Sep 15 |
| Radishes | — | — | Mar 23 – May 4 | Sep 8 – Sep 29 |
| Cucumbers | Mar 30 – Apr 6 | May 11 – May 18 | May 4 – May 18 | Aug 4 – Aug 18 |
| Zucchini & Summer Squash | Mar 30 – Apr 6 | — | May 4 – May 18 | Aug 11 – Aug 25 |
| Winter Squash & Pumpkins | Mar 30 – Apr 6 | — | May 4 – May 18 | — |
| Melons & Watermelon | Mar 30 – Apr 6 | May 11 – May 25 | — | — |
| Carrots | — | — | Apr 6 – May 4 | Jul 28 – Aug 11 |
| Beets | — | — | Apr 6 – May 4 | Aug 11 – Aug 25 |
| Potatoes | — | — | Apr 6 – Apr 27 | — |
| Swiss Chard | — | — | Apr 13 – May 11 | Aug 11 – Aug 25 |
| Cilantro | — | — | Apr 13 – May 4 | Aug 25 – Sep 15 |
| Green Beans | — | — | May 4 – May 25 | Aug 4 – Aug 18 |
| Sweet Corn | — | — | May 4 – May 18 | — |
| Sweet Potatoes | — | May 11 – Jun 1 | — | — |
| Garlic | — | — | — | Oct 6 – Nov 10 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Carleton 2w, MI weather station, 14 km away (elevation 627 ft (191 m)).
Frost dates near Flat Rock
- South Rockwood Apr 27 · Oct 22
- Trenton Apr 20 · Oct 27
- Rockwood Apr 27 · Oct 22
- New Boston Apr 20 · Oct 27
- Riverview Apr 20 · Oct 27
- Carleton Apr 27 · Oct 20
- Grosse Ile Apr 20 · Oct 27
- Southgate Apr 20 · Oct 27
- Taylor Apr 20 · Oct 27
- Newport Apr 27 · Oct 22
Frequently asked questions
When is the last frost in Flat Rock, MI?
The median last spring frost in Flat Rock, MI is April 27. There is still about a 10% chance of frost after May 13, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Flat Rock, MI?
The median first fall frost is October 20, with about a 10% chance of frost before October 4.
How long is the growing season in Flat Rock, MI?
About 176 days between the median last spring frost and first fall frost.
What planting zone is Flat Rock, MI?
Flat Rock, MI is in USDA hardiness zone 6b.