Montana
Planting zones in Roosevelt County, Montana
Every ZIP code in this county is USDA zone 4a — so unlike most of the places people look up, there is one right answer here and it holds wherever you are in the county.
Your ZIP code
Get the exact answer for your address
Everything above describes Roosevelt County, Montana 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 Roosevelt County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 14 – September 28 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 13 – March 29 — counted back from a last spring freeze of May 8 – May 24 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 24 – September 14 as growing season (113 days). Widening to any single station gives May 8 – September 28 (143 days).
That is a 30-day difference inside one county — 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
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 110–143 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 80.1–84 °F in June–August. Summer rain over the same months runs 6.9–7.2" 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 54% 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 84 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Roosevelt 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 |
|---|---|---|---|
| 59201 | 4a | Wolf Pt, MT | 4.9 km |
| 59212 | 4a | Culbertson, MT | 28.3 km |
| 59213 | 4a | Wolf Point 29 Ene, MT | 20.7 km |
| 59218 | 4a | Culbertson, MT | 8.4 km |
| 59226 | 4a | Medicine Lake 3 SE, MT | 16.1 km |
| 59255 | 4a | Wolf Point 29 Ene, MT | 9.0 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 Roosevelt 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 13 – March 29 | 8 wk before |
| 🌶️ Peppers | Start indoors | March 13 – March 29 | 8 wk before |
| 🥦 Broccoli | Start indoors | March 27 – April 12 | 6 wk before |
| 🥬 Cabbage | Start indoors | March 27 – April 12 | 6 wk before |
| 🥬 Collards | Start indoors | March 27 – April 12 | 6 wk before |
| 🥬 Kale | Start indoors | March 27 – April 12 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | March 27 – April 12 | 6 wk before |
| 🫛 Peas | Direct sow | March 27 – April 12 | 6 wk before |
| 🥬 Spinach | Direct sow | March 27 – April 12 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | March 27 – April 12 | 6 wk before |
| 🍅 Tomatoes | Start indoors | March 27 – April 12 | 6 wk before |
| 🥬 Bok Choy | Start indoors | April 3 – April 19 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | April 3 – April 19 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | April 3 – April 19 | 5 wk before |
| 🥬 Arugula | Direct sow | April 10 – April 26 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | April 10 – April 26 | 4 wk before |
| 🥕 Beets | Direct sow | April 10 – April 26 | 4 wk before |
| 🧅 Green Onions | Direct sow | April 10 – April 26 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | April 10 – April 26 | 4 wk before |
| 🌶️ Okra | Start indoors | April 10 – April 26 | 4 wk before |
| 🌱 Radishes | Direct sow | April 10 – April 26 | 4 wk before |
| 🥔 Turnips | Direct sow | April 10 – April 26 | 4 wk before |
| 🥬 Cabbage | Set out | April 17 – May 3 | 3 wk before |
| 🥕 Carrots | Direct sow | April 17 – May 3 | 3 wk before |
| 🥬 Collards | Direct sow | April 17 – May 3 | 3 wk before |
| 🥬 Collards | Set out | April 17 – May 3 | 3 wk before |
| 🥒 Cucumbers | Start indoors | April 17 – May 3 | 3 wk before |
| 🧅 Green Onions | Set out | April 17 – May 3 | 3 wk before |
| 🥬 Kale | Direct sow | April 17 – May 3 | 3 wk before |
| 🥬 Kale | Set out | April 17 – May 3 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | April 17 – May 3 | 3 wk before |
| 🥬 Kohlrabi | Set out | April 17 – May 3 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | April 17 – May 3 | 3 wk before |
| 🎃 Pumpkins | Start indoors | April 17 – May 3 | 3 wk before |
| 🎃 Summer Squash | Start indoors | April 17 – May 3 | 3 wk before |
| 🎃 Winter Squash | Start indoors | April 17 – May 3 | 3 wk before |
| 🥒 Zucchini | Start indoors | April 17 – May 3 | 3 wk before |
| 🥬 Bok Choy | Direct sow | April 24 – May 10 | 2 wk before |
| 🥬 Bok Choy | Set out | April 24 – May 10 | 2 wk before |
| 🥦 Broccoli | Set out | April 24 – May 10 | 2 wk before |
| 🌿 Cilantro | Direct sow | April 24 – May 10 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | April 24 – May 10 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | April 24 – May 10 | 2 wk before |
| 🥬 Swiss Chard | Set out | April 24 – May 10 | 2 wk before |
| 🌿 Dill | Direct sow | May 1 – May 17 | 1 wk before |
| 🫘 Bush Beans | Direct sow | May 15 – May 31 | 1 wk after |
| 🥒 Cucumbers | Set out | May 15 – May 31 | 1 wk after |
| 🎃 Pumpkins | Direct sow | May 15 – May 31 | 1 wk after |
| 🎃 Pumpkins | Set out | May 15 – May 31 | 1 wk after |
| 🎃 Summer Squash | Direct sow | May 15 – May 31 | 1 wk after |
| 🎃 Summer Squash | Set out | May 15 – May 31 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | May 15 – May 31 | 1 wk after |
| 🍅 Tomatoes | Set out | May 15 – May 31 | 1 wk after |
| 🎃 Winter Squash | Direct sow | May 15 – May 31 | 1 wk after |
| 🎃 Winter Squash | Set out | May 15 – May 31 | 1 wk after |
| 🥒 Zucchini | Direct sow | May 15 – May 31 | 1 wk after |
| 🥒 Zucchini | Set out | May 15 – May 31 | 1 wk after |
| 🥒 Cucumbers | Direct sow | May 22 – June 7 | 2 wk after |
| 🌶️ Okra | Direct sow | May 22 – June 7 | 2 wk after |
| 🌶️ Okra | Set out | May 22 – June 7 | 2 wk after |
| 🌶️ Peppers | Set out | May 22 – June 7 | 2 wk after |
| 🫘 Southern Peas | Direct sow | May 22 – June 7 | 2 wk after |
| 🍠 Sweet Potato | Set out | May 22 – June 7 | 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 lives through a zone 4a winter
Of 74 perennial edibles, 34 come through a zone 4a winter — and 0 fail here for being too warm rather than too cold, needing more winter chill than this county gets or more heat than they tolerate. Among the ones that work: Cranberry, Honeyberry, Lingonberry, Apple, Aronia, Black Currant, Elderberry, Gooseberry.
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 6 to be careful. Median May 8 – May 24 across 4 stations; April 25 is the optimistic end.
- First fall freeze
- Plan to September 1 to be careful. Median September 14 – September 28 across 4 stations; October 11 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 42 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 |
|---|---|---|---|---|
| Culbertson, MT | USC00242122 | May 21 | September 20 | 120 days |
| Medicine Lake 3 SE, MT | USC00245572 | May 16 | September 18 | 125 days |
| Wolf Point 29 Ene, MT | USW00094060 | May 24 | September 14 | 110 days |
| Wolf Pt, MT | USC00249103 | May 8 | September 28 | 143 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
Roosevelt County sits in Montana. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of Montana
- Teton County, MT 4a–4b
- Liberty County, MT 4a
- Pondera County, MT 4a–4b
- Flathead County, MT 4b–6a
- Lake County, MT 5b–6a
- Madison County, MT 4b–5a
- Big Horn County, MT 4b–5a
- Sheridan County, MT 3b–4a
- Valley County, MT 3b–4a
- Fergus County, MT 4b
- Park County, MT 4a–5a
- Ravalli County, MT 5a–5b
Counties with the same zones — 4a
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 4a 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 4a, 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.