Frost dates · USDA zone 6a
Frost dates for Ann Arbor, MI
Ann Arbor, MI sees its last 32 °F night of spring around May 5 and its first of fall around October 10 — a 157-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Apr 21 | Oct 24 |
| Median — 1 year in 2 | May 5 | Oct 10 |
| 1 year in 10 | May 20 | Sep 28 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 157 days median, at least 138 in 9 years of 10, at least 176 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Apr 24 and first of Oct 23.
Ann Arbor planting calendar, 2027
Every row runs from the median last frost (May 5) and median first frost (Oct 10) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Feb 10 | Apr 7 | Jul 26 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | May 5 | Jun 4 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Apr 21 | Apr 21 | Jun 5 | 45 from sow |
| Genovese BasilGenovese | Apr 7 | May 19 | Jul 18 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Mar 10 | May 12 | Jul 26 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Feb 24 | May 19 | Aug 22 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Mar 10 | May 12 | Jul 26 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Mar 10 | May 12 | Jul 31 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Mar 10 | May 12 | Jul 31 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Apr 21 | Apr 21 | Jun 30 | 70 from sow |
| TomatilloToma Verde | Mar 24 | May 12 | Jul 21 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Mar 24 | May 12 | Jul 26 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Mar 24 | May 12 | Jul 31 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Ann Arbor grow?
Each sauce, scheduled for a Ann Arbor container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Ann Arbor frost questions
When is the last frost in Ann Arbor, MI?
The median last 32 °F freeze at ANN ARBOR SE, MI is May 5: half of years see a later one. One year in ten, a freeze still comes after May 20; nine years in ten, it comes after April 21. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Ann Arbor, MI?
The median first 32 °F freeze of fall is October 10. One year in ten it arrives before September 28; nine years in ten, before October 24.
How long is the growing season in Ann Arbor, MI?
157 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 138 days; one year in ten, at least 176 days.
What growing zone is Ann Arbor, MI?
USDA hardiness zone 6a, per the 2023 USDA Plant Hardiness Zone Map for ZIP 48104. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Ann Arbor, MI?
Start Roma VF (determinate paste) seeds indoors around Mar 24 and transplant around May 12, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for May 20. First ripe fruit lands around Jul 26.
When should I plant peppers in Ann Arbor, MI?
Sow jalapeño indoors on a heat mat around Mar 10; transplant no earlier than May 12, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jul 26.
Nearby in Michigan
- Westlandlast frost May 1
- Novilast frost May 1
- Livonialast frost May 1
- Dearborn Heightslast frost May 1
- Farmington Hillslast frost May 1
- Taylorlast frost Apr 20
All Michigan frost dates → · How frost-date math drives a sowing calendar →