Sun River, Montana, sits in USDA hardiness zone 4a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Well-matched crops include cabbage, cranberry, turkish rocket, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Sun River, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Sun River lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Sun River — soil, climate, flood, and parcel records. How we handle your address.
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Sun River — the short answer
Sun River, Montana: USDA zone 4a, about 161 days between hard freezes, across 1K acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~161
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 1K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 4a is Sun River's average, not your lot's — a low corner or a tree line moves it. Against Sun River's 161-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sun River
Each reading below is measured for Sun River itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSun River runs about 161 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSun River sits in USDA hardiness zone 4a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Sun River is in
Sun River sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Sun River's own centroid rather than borrowed from Cascade County.
What Grows in Sun River
Every plant below cleared Sun River's own zone 4a and its 161-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Sun River?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 4; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 10 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Sun River
Closest first, within ~10 miles of Sun River. Listing isn't leaking, and distance isn't exposure.
- BIG SKY SCIENTIFIC LLCBrownfields · 550 ft
- BIG SKY SCIENTIFIC LLCToxics Release Inventory · 550 ft
- SUN RIVER GROCERYUnderground Storage Tanks · 750 ft
- MDOT SUN RIVER MAINTENANCEUnderground Storage Tanks · 750 ft
- CASCADE COLONY INCUnderground Storage Tanks · 2100 ft
- MALMSTROM AFB H 5Underground Storage Tanks · 1.6 mi
- MALMSTROM AFB H 4Underground Storage Tanks · 1.6 mi
- SUN RIVER FARMERS COOPUnderground Storage Tanks · 2.5 mi
- STEINBACH FEEDLOTCAFO · 4.0 mi
- BN SHAW BUTTE MICROWAVEUnderground Storage Tanks · 4.5 mi
- 21N01W02CCBC01Nitrate · 4.8 mi
- LEWIS CONSTRUCTION CO VAUGHNUnderground Storage Tanks · 5.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sun River's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Sun River.
Total Sites
50
within ~10 miles of Sun River
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Sun River
Severity Distribution
within ~10 miles of Sun River
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sun River, two things run higher than the national average within ~10 miles of Sun River — CAFO (3 sites) and Nitrate (16 sites). That's not a problem with your land — it's information about it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Sun River
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Sun River average
Your land is one point inside Sun River
Everything above resolves to Sun River as a whole — one PHZM band and one 28°F frost record, read across 1K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Sun River Average
Sun River Average
- ●USDA Zones 4a, averaged across Sun River
- ●One soil character for all of Sun River
- ●Frost dates read at Sun River's scale: May 2 to Oct 10
YOUR Parcel
- ✓Your exact zone, not Sun River's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sun River
Pull a site-specific report for your exact address in Sun River, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sun River averages can't show:
We read public map data around Sun River — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sun River average
How we know this about Sun River
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Sun River’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Sun River
When does frost risk typically end in Sun River?
The last hard freeze (28°F) in Sun River typically lands around May 2, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 23.
When is the first frost in Sun River?
The first hard freeze (28°F) in Sun River typically arrives around Oct 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 26, so the watching starts about Sep 10 — about 161 days after the spring freeze cleared.
How long is the growing season in Sun River?
Measured between 28°F hard freezes, Sun River sees about 161 frost-free days — roughly May 2 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 23 to Sep 26, about 126 days.
Is the soil safe to grow vegetables in Sun River?
The federal record around Sun River shows 50 documented sites, mostly Underground Storage Tanks entries (29), the nearest Brownfields record about 0.1 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Sun River?
From about Sep 10 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 10 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 10. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sun River's scale — its 4a band and its 161-day season. Your yard writes its own version of Sun River's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Sun River’s own scale
6 of the readings below were taken at Sun River's own scale — its own ~161-day season between 28°F freezes, the 1,191 acres it covers and 50 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Sun River's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Sun River's own 28°F hard-freeze dates, about May 2 and Oct 10 and the ~161-day span between themNOAA 1991–2020 Climate Normals
- 50 documented contamination sites on the federal record near Sun River, the closest Brownfields record about 0.1 miles out from the town centreFederal environmental registers
- Sun River's boundary and the 1,191 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~161-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sun River's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Sun River's 1,191 acres read through its county's SSURGO summaryfrom Cascade County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cascade County
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Cascade County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sun River's 1,191 acreswhy one lot differs from the next →
- Which side of Sun River you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,191 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.1 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Sun River-wide figureread your own land →