Michigan
Planting zones in Ontonagon County, Michigan
This county spans USDA zones 4b to 5a, so there is no single zone for Ontonagon County and anyone who gives you one is rounding. 75% of its ZIP codes are zone 4b; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Ontonagon County, Michigan 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 Ontonagon County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 19 – October 1 across the 4 NOAA stations serving this county .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around March 28 – April 5 — counted back from a last spring freeze of May 23 – May 31 here.
These are ranges across the whole county. The ZIP lookup above gives the dates from your own nearest station instead.
All 4 stations agreeAt least one station
Every one of the 4 NOAA stations serving this county counts May 31 – September 19 as growing season (111 days). Widening to any single station gives May 23 – October 1 (131 days).
Which zone you are in depends where you are
Ontonagon County covers 2 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 75% in zone 4b and wrong for the other 25%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 4b | 6 | 75% | |
| 5a | 2 | 25% |
Zones are published per ZIP code, so yours is exact even though the county's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Across the 4 NOAA stations serving this county. These are medians — half of years freeze later than the date shown — so treat the later end of each range as the cautious one.
The growing season runs 111–128 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 74.1–77.7 °F in June–August. Summer rain over the same months runs 9.0–11.3" across those 4 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 84% 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 76 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Ontonagon County
Zones are published per ZIP code, not per county, so this is the exact answer rather than the county'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 |
|---|---|---|---|
| 49910 | 4b | Bergland Dam, MI | 4.9 km |
| 49912 | 4b | Paulding, MI | 11.1 km |
| 49925 | 4b | Bergland Dam, MI | 14.0 km |
| 49929 | 5a | Greenland 6N, MI | 8.3 km |
| 49948 | 4b | Greenland 6N, MI | 15.6 km |
| 49953 | 5a | Ontonagon 6 SE, MI | 17.5 km |
| 49960 | 4b | Ontonagon 6 SE, MI | 14.1 km |
| 49971 | 4b | Bergland Dam, MI | 15.1 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.
When to start seeds in Ontonagon County
Every date below is anchored on the last spring freeze at each station and reported as a range across all 4 of them, because no one station speaks for the county.
| Crop | Job | When | Offset |
|---|---|---|---|
| 🧅 Green Onions | Start indoors | March 28 – April 5 | 8 wk before |
| 🌶️ Peppers | Start indoors | March 28 – April 5 | 8 wk before |
| 🥦 Broccoli | Start indoors | April 11 – April 19 | 6 wk before |
| 🥬 Cabbage | Start indoors | April 11 – April 19 | 6 wk before |
| 🥬 Collards | Start indoors | April 11 – April 19 | 6 wk before |
| 🥬 Kale | Start indoors | April 11 – April 19 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | April 11 – April 19 | 6 wk before |
| 🫛 Peas | Direct sow | April 11 – April 19 | 6 wk before |
| 🥬 Spinach | Direct sow | April 11 – April 19 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | April 11 – April 19 | 6 wk before |
| 🍅 Tomatoes | Start indoors | April 11 – April 19 | 6 wk before |
| 🥬 Bok Choy | Start indoors | April 18 – April 26 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | April 18 – April 26 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | April 18 – April 26 | 5 wk before |
| 🥬 Arugula | Direct sow | April 25 – May 3 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | April 25 – May 3 | 4 wk before |
| 🥕 Beets | Direct sow | April 25 – May 3 | 4 wk before |
| 🧅 Green Onions | Direct sow | April 25 – May 3 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | April 25 – May 3 | 4 wk before |
| 🌶️ Okra | Start indoors | April 25 – May 3 | 4 wk before |
| 🌱 Radishes | Direct sow | April 25 – May 3 | 4 wk before |
| 🥔 Turnips | Direct sow | April 25 – May 3 | 4 wk before |
| 🥬 Cabbage | Set out | May 2 – May 10 | 3 wk before |
| 🥕 Carrots | Direct sow | May 2 – May 10 | 3 wk before |
| 🥬 Collards | Direct sow | May 2 – May 10 | 3 wk before |
| 🥬 Collards | Set out | May 2 – May 10 | 3 wk before |
| 🥒 Cucumbers | Start indoors | May 2 – May 10 | 3 wk before |
| 🧅 Green Onions | Set out | May 2 – May 10 | 3 wk before |
| 🥬 Kale | Direct sow | May 2 – May 10 | 3 wk before |
| 🥬 Kale | Set out | May 2 – May 10 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | May 2 – May 10 | 3 wk before |
| 🥬 Kohlrabi | Set out | May 2 – May 10 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | May 2 – May 10 | 3 wk before |
| 🎃 Pumpkins | Start indoors | May 2 – May 10 | 3 wk before |
| 🎃 Summer Squash | Start indoors | May 2 – May 10 | 3 wk before |
| 🎃 Winter Squash | Start indoors | May 2 – May 10 | 3 wk before |
| 🥒 Zucchini | Start indoors | May 2 – May 10 | 3 wk before |
| 🥬 Bok Choy | Direct sow | May 9 – May 17 | 2 wk before |
| 🥬 Bok Choy | Set out | May 9 – May 17 | 2 wk before |
| 🥦 Broccoli | Set out | May 9 – May 17 | 2 wk before |
| 🌿 Cilantro | Direct sow | May 9 – May 17 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | May 9 – May 17 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | May 9 – May 17 | 2 wk before |
| 🥬 Swiss Chard | Set out | May 9 – May 17 | 2 wk before |
| 🌿 Dill | Direct sow | May 16 – May 24 | 1 wk before |
| 🫘 Bush Beans | Direct sow | May 30 – June 7 | 1 wk after |
| 🥒 Cucumbers | Set out | May 30 – June 7 | 1 wk after |
| 🎃 Pumpkins | Direct sow | May 30 – June 7 | 1 wk after |
| 🎃 Pumpkins | Set out | May 30 – June 7 | 1 wk after |
| 🎃 Summer Squash | Direct sow | May 30 – June 7 | 1 wk after |
| 🎃 Summer Squash | Set out | May 30 – June 7 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | May 30 – June 7 | 1 wk after |
| 🍅 Tomatoes | Set out | May 30 – June 7 | 1 wk after |
| 🎃 Winter Squash | Direct sow | May 30 – June 7 | 1 wk after |
| 🎃 Winter Squash | Set out | May 30 – June 7 | 1 wk after |
| 🥒 Zucchini | Direct sow | May 30 – June 7 | 1 wk after |
| 🥒 Zucchini | Set out | May 30 – June 7 | 1 wk after |
| 🥒 Cucumbers | Direct sow | June 6 – June 14 | 2 wk after |
| 🌶️ Okra | Direct sow | June 6 – June 14 | 2 wk after |
| 🌶️ Okra | Set out | June 6 – June 14 | 2 wk after |
| 🌶️ Peppers | Set out | June 6 – June 14 | 2 wk after |
| 🫘 Southern Peas | Direct sow | June 6 – June 14 | 2 wk after |
| 🍠 Sweet Potato | Set out | June 6 – June 14 | 2 wk after |
Offsets are published guidance; the dates they land on are computed from measured NOAA normals. The seed-starting tool does this for your own ZIP code and counts the days.
What survives the winter changes across Ontonagon County
Zone 5a carries 48 of 74 perennial edibles; zone 4b carries 34. The best number is not always the warmest zone — the count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat, not to cold.
Hardiness ranges are a judgement, published by growers rather than measured; the zone they are compared against is measured. On a warm-end verdict, check with your local extension service — a coastal zone 8 and an inland zone 8 are not the same summer.
Cautious — shortens the seasonMedian across stationsOptimistic
- Last spring freeze
- Plan to June 13 to be careful. Median May 23 – May 31 across 4 stations; May 6 is the optimistic end.
- First fall freeze
- Plan to September 2 to be careful. Median September 19 – October 1 across 4 stations; October 16 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 4 stations behind these numbers
All 4 NOAA stations whose normals this page quotes, spanning about 53 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 county.
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.
These are the stations this county's ZIP codes actually cite as nearest — not a claim that each one sits inside its boundary, since a rural ZIP legitimately reaches over it. Every figure above comes from them, and each is named so you can check it.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Bergland Dam, MI | USC00200718 | May 26 | September 27 | 123 days |
| Greenland 6N, MI | USC00203421 | May 23 | October 1 | 128 days |
| Ontonagon 6 SE, MI | USC00206220 | May 27 | October 1 | 127 days |
| Paulding, MI | USC00206398 | May 31 | September 19 | 111 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Your own ZIP
Work out your own dates
This page describes a whole county. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.
Other places to compare
Ontonagon County sits in Michigan. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of Michigan
- Newaygo County, MI 5a–6a
- Baraga County, MI 4a–5a
- Cheboygan County, MI 4b–5a
- Charlevoix County, MI 5a–6a
- Ogemaw County, MI 5a
- Houghton County, MI 4b–5b
- Lenawee County, MI 6a
- Sanilac County, MI 6a
- Chippewa County, MI 4b–5b
- Allegan County, MI 6a–6b
- Van Buren County, MI 6a–6b
- Huron County, MI 6a
Counties with the same zones — 4b–5a
Matched on the exact zone set, not a dominant zone, so the winter answer on these pages really is the same one as here.
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 4b 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 4b, 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
Hardiness zones are the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. Freeze dates and growing-season lengths are NOAA 1991–2020 Climate Normals, taken per station and cited above by name and NOAA ID.
County boundaries come from the Census ZCTA-to-county relation, which is what places each ZIP code — and which treats parishes, boroughs and census areas as county equivalents. No station is chosen to represent this county: every range above is taken across all of them and the count is stated, because picking one would be a judgement dressed as a measurement.