Place guide
Planting zones in Ann Arbor, MI
Every ZIP code in this metro is USDA zone 6a. That is unusual — most metros span several zones — and it means the one number people usually look up is the same wherever you are here.
Your ZIP code
Get the exact answer for your address
Everything above describes Ann Arbor, MI as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.
The growing season in Ann Arbor, MI is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives October 4 – October 24 across the 9 NOAA stations serving this metro area .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around February 27 – March 13 — counted back from a last spring freeze of April 24 – May 8 here.
These are ranges across the whole metro area. The ZIP lookup above gives the dates from your own nearest station instead.
All 9 stations agreeAt least one station
Every one of the 9 NOAA stations serving this metro area counts May 8 – October 4 as growing season (149 days). Widening to any single station gives April 24 – October 24 (183 days).
That is a 34-day difference inside one metro area — which is why this page gives ranges rather than a single planting date. The ZIP lookup above resolves it to one station.
Your freeze dates
Those are the earliest and latest medians among the 9 stations serving this metro — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
The spread is the point. Even in a metro that is one hardiness zone throughout, its stations disagree about the last spring freeze. Hardiness zone and frost date measure different things — a zone is the average annual coldest night, a freeze date is when the season turns — and a place can be uniform in one and varied in the other. Use the tools below with your own ZIP rather than the ends of this range.
Your growing season
NOAA publishes a growing-season length for each station, and across the 9 stations serving Ann Arbor, MI it runs 147–179 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 79–84 °F , below the 90 °F point where cool-season crops reliably bolt. Summer rain over the same months runs 9.1–11.4" across those 8 stations, against the rough inch a week — about 13 inches over the same 92 days — that a vegetable garden is usually reckoned to want. The middle station covers about 79% of it, so expect to make up the rest. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 82 °F summer afternoon drying the soil faster than a cool one.
When to start seeds in Ann Arbor, MI
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 9 stations — the earliest and latest that job falls anywhere in the metro — because no one station speaks for the whole area.
| Crop | Job | When | Offset |
|---|---|---|---|
| Green Onions | Start indoors | February 27 – March 13 | 8 weeks before |
| Peppers | Start indoors | February 27 – March 13 | 8 weeks before |
| Broccoli | Start indoors | March 13 – March 27 | 6 weeks before |
| Cabbage | Start indoors | March 13 – March 27 | 6 weeks before |
| Collards | Start indoors | March 13 – March 27 | 6 weeks before |
| Kale | Start indoors | March 13 – March 27 | 6 weeks before |
| Leaf Lettuce | Start indoors | March 13 – March 27 | 6 weeks before |
| Peas | Direct sow | March 13 – March 27 | 6 weeks before |
| Spinach | Direct sow | March 13 – March 27 | 6 weeks before |
| Sweet Potato | Start indoors | March 13 – March 27 | 6 weeks before |
| Tomatoes | Start indoors | March 13 – March 27 | 6 weeks before |
| Bok Choy | Start indoors | March 20 – April 3 | 5 weeks before |
| Kohlrabi | Start indoors | March 20 – April 3 | 5 weeks before |
| Swiss Chard | Start indoors | March 20 – April 3 | 5 weeks before |
| Arugula | Direct sow | March 27 – April 10 | 4 weeks before |
| Baby Salad Greens | Direct sow | March 27 – April 10 | 4 weeks before |
| Beets | Direct sow | March 27 – April 10 | 4 weeks before |
| Green Onions | Direct sow | March 27 – April 10 | 4 weeks before |
| Mustard Greens | Direct sow | March 27 – April 10 | 4 weeks before |
| Okra | Start indoors | March 27 – April 10 | 4 weeks before |
| Radishes | Direct sow | March 27 – April 10 | 4 weeks before |
| Turnips | Direct sow | March 27 – April 10 | 4 weeks before |
| Cabbage | Set out | April 3 – April 17 | 3 weeks before |
| Carrots | Direct sow | April 3 – April 17 | 3 weeks before |
| Collards | Direct sow | April 3 – April 17 | 3 weeks before |
| Collards | Set out | April 3 – April 17 | 3 weeks before |
| Cucumbers | Start indoors | April 3 – April 17 | 3 weeks before |
| Green Onions | Set out | April 3 – April 17 | 3 weeks before |
| Kale | Direct sow | April 3 – April 17 | 3 weeks before |
| Kale | Set out | April 3 – April 17 | 3 weeks before |
| Kohlrabi | Direct sow | April 3 – April 17 | 3 weeks before |
| Kohlrabi | Set out | April 3 – April 17 | 3 weeks before |
| Leaf Lettuce | Direct sow | April 3 – April 17 | 3 weeks before |
| Pumpkins | Start indoors | April 3 – April 17 | 3 weeks before |
| Summer Squash | Start indoors | April 3 – April 17 | 3 weeks before |
| Winter Squash | Start indoors | April 3 – April 17 | 3 weeks before |
| Zucchini | Start indoors | April 3 – April 17 | 3 weeks before |
| Bok Choy | Direct sow | April 10 – April 24 | 2 weeks before |
| Bok Choy | Set out | April 10 – April 24 | 2 weeks before |
| Broccoli | Set out | April 10 – April 24 | 2 weeks before |
| Cilantro | Direct sow | April 10 – April 24 | 2 weeks before |
| Leaf Lettuce | Set out | April 10 – April 24 | 2 weeks before |
| Swiss Chard | Direct sow | April 10 – April 24 | 2 weeks before |
| Swiss Chard | Set out | April 10 – April 24 | 2 weeks before |
| Dill | Direct sow | April 17 – May 1 | 1 week before |
| Bush Beans | Direct sow | May 1 – May 15 | 1 week after |
| Cucumbers | Set out | May 1 – May 15 | 1 week after |
| Pumpkins | Direct sow | May 1 – May 15 | 1 week after |
| Pumpkins | Set out | May 1 – May 15 | 1 week after |
| Summer Squash | Direct sow | May 1 – May 15 | 1 week after |
| Summer Squash | Set out | May 1 – May 15 | 1 week after |
| Sweet Corn | Direct sow | May 1 – May 15 | 1 week after |
| Tomatoes | Set out | May 1 – May 15 | 1 week after |
| Winter Squash | Direct sow | May 1 – May 15 | 1 week after |
| Winter Squash | Set out | May 1 – May 15 | 1 week after |
| Zucchini | Direct sow | May 1 – May 15 | 1 week after |
| Zucchini | Set out | May 1 – May 15 | 1 week after |
| Cucumbers | Direct sow | May 8 – May 22 | 2 weeks after |
| Okra | Direct sow | May 8 – May 22 | 2 weeks after |
| Okra | Set out | May 8 – May 22 | 2 weeks after |
| Peppers | Set out | May 8 – May 22 | 2 weeks after |
| Southern Peas | Direct sow | May 8 – May 22 | 2 weeks after |
| Sweet Potato | Set out | May 8 – May 22 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What lives through a zone 6a winter
Winter hardiness runs on the zone alone, so this one is exact for the whole of Ann Arbor, MI rather than a range. Of 74 perennial fruits, nuts, berries, vegetables and herbs, 51 come through a zone 6a winter .
Among them: Cranberry, Honeyberry, Lingonberry, Apple, Aronia, Black Currant, Elderberry, Gooseberry. See the full list with reasons.
Cautious — shortens the seasonMedian across stationsOptimistic
- Last spring freeze
- Plan to May 26 to be careful. Median April 24 – May 8 across 9 stations; April 10 is the optimistic end.
- First fall freeze
- Plan to September 20 to be careful. Median October 4 – October 24 across 9 stations; November 6 is the optimistic end.
NOAA publishes these as probabilities, not averages — the middle figure is a median, so half of years fall either side of it. The cautious end is the 10% tail: in roughly nine years in ten the freeze falls on the safe side of it.
The 9 stations behind these numbers
All 9 NOAA stations whose normals this page quotes, spanning about 41 km north to south. Every one is named with its identifier in the station list below — this page does not single one out, because no one station speaks for a whole metro area.
A relative sketch, not a map with a projection: longitude is adjusted for latitude so the shape is not stretched, and there is no basemap. For the one station nearest a specific address, with its real distance, use the ZIP lookup above.
Every figure above comes from these, and each is named so you can check it. Which station serves a given ZIP code, and how far away it is, varies across the metro — the table below gives it per ZIP code rather than this page averaging it.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Ann Arbor Muni AP, MI | USW00094889 | May 8 | October 4 | 147 days |
| Ann Arbor SE, MI | USC00200228 | May 5 | October 10 | 157 days |
| Ann Arbor U Of Mich, MI | USC00200230 | May 3 | October 13 | 160 days |
| Chelsea, MI | USC00201502 | April 30 | October 12 | 163 days |
| Detroit Willow Run AP, MI | USW00014853 | April 24 | October 24 | 179 days |
| Manchester, MI | USC00205050 | April 30 | October 14 | 165 days |
| Milan 4 Ese, MI | USC00205450 | May 3 | October 10 | 158 days |
| Saline 4Sw, MI | USC00207312 | May 2 | October 11 | 160 days |
| Whitmore Lake 1Nw, MI | USC00208972 | May 5 | October 13 | 160 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Every ZIP code in Ann Arbor, MI
Zones are published per ZIP code, not per metro area, so this is the exact answer rather than the metro area's average. The station column is the nearest one to that ZIP code's centroid and how far away it is — the same figure the tools use, shown here so you can see which ZIP codes are well covered and which are reaching.
| ZIP code | USDA zone | Nearest NOAA station | Distance |
|---|---|---|---|
| 48103 | 6a | Ann Arbor Muni AP, MI | 9.4 km |
| 48104 | 6a | Ann Arbor SE, MI | 3.0 km |
| 48105 | 6a | Ann Arbor U Of Mich, MI | 4.2 km |
| 48108 | 6a | Ann Arbor Muni AP, MI | 1.0 km |
| 48109 | 6a | Ann Arbor U Of Mich, MI | 3.7 km |
| 48118 | 6a | Chelsea, MI | 2.3 km |
| 48130 | 6a | Chelsea, MI | 9.5 km |
| 48158 | 6a | Manchester, MI | 0.7 km |
| 48176 | 6a | Saline 4Sw, MI | 1.7 km |
| 48189 | 6a | Whitmore Lake 1Nw, MI | 2.9 km |
| 48190 | 6a | Milan 4 Ese, MI | 7.4 km |
| 48191 | 6a | Milan 4 Ese, MI | 7.5 km |
| 48197 | 6a | Ann Arbor SE, MI | 6.9 km |
| 48198 | 6a | Detroit Willow Run AP, MI | 6.4 km |
ZIP-code positions are area centroids, so a large rural ZIP code's listed distance is measured from the middle of its area rather than from any particular address in it.
Your own ZIP
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
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What survives my winter?
Runs on the hardiness zone, so it answers for all of Ann Arbor, MI at once — zone 6a across 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Other places to compare
These metros are also entirely zone 6a, so the winter answer here is the same one they get — the freeze dates and the spring calendar are their own.
- Battle Creek, MI — zone 6a
- Lima, OH — zone 6a
- Mansfield, OH — zone 6a
- Muncie, IN — zone 6a
- Pueblo, CO — zone 6a
- Elkhart-Goshen, IN — zone 6a
- Kokomo, IN — zone 6a
- Midland, MI — zone 6a
Gardening in Michigan — zones 4a– 7a covers the whole state: how its 991 ZIP codes divide between 7 hardiness zones, and the freeze dates across every NOAA station in it.
Other metro areas in MI:
- Muskegon-Norton Shores, MI Zones 6a–6b
- Battle Creek, MI Zone 6a
- Bay City, MI Zones 5b–6a
- Midland, MI Zone 6a
- Detroit-Warren-Dearborn, MI Zones 6a–6b
- Grand Rapids-Wyoming-Kentwood, MI Zones 5b–7a
- Lansing-East Lansing, MI Zone 6a
- Traverse City, MI Zones 5a–6b
- Flint, MI Zone 6a
- Niles, MI Zones 6a–6b
- Jackson, MI Zone 6a
- Saginaw, MI Zone 6a
Gear
If you want to act on this
Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.
- Trunk wrapZone 6a is cold enough that winter sun on a young trunk does more damage than the cold does.
- Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.
- MulchFor the perennials nearest their cold limit in zone 6a, where an insulated crown is what decides whether they come back.
As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.
Sources
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates are NOAA's 1991–2020 Climate Normals, read from every station whose normals cover a ZIP code in this metro. Nothing here is estimated, and no station stands in for another.
This page names no single station on purpose. Picking one to represent a metro sounds reasonable and is not: the station serving the most ZIP codes is an artifact of where ZIP centroids happen to fall, and it selects a lock on the Monongahela for Pittsburgh and a far southern suburb for Chicago. A range across every station is true; a single cited date for a whole metro is not.