Sun River, Montana, sits in USDA hardiness zones 3a-4b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Well-matched crops include cherry, potato, lentil, and ponderosa pine, 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 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
3a-4b
Last Hard Freeze (28°F)
Apr 28
Town normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Oct 17
Town normal — light frosts arrive a few weeks earlier
Town Area
1K acres
Hardiness Zone Range
Zone maps are averages across Sun River. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil varies lot by lot — soil types explained.
What Grows in Sun River
Plants matched to Sun River's USDA zones 3a-4b — each links to its full growing profile.
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 Mar 31; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 28 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 17 — 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.
Growing Challenges in Montana
What an experienced grower plans around here — each one has a move.
Very short growing season (60-100 frost-free days)
At 60-100 frost-free days, a high tunnel or cold frame isn't a luxury — it's the difference-maker Montana growers rely on.
Low rainfall requires irrigation in most areas
Drip irrigation plus mulch stretches scarce water a long way — plan the system before the first seed.
Extreme winter cold (-40F possible)
Choose perennials rated for the cold you actually get — a -40°F winter audits every optimistic zone push.
For cultivar selection, pest pressure, and planting-time guidance specific to Montana, the Montana State University Extension is the authoritative local source.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
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 — 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 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Sun River Average
- ●USDA Zones 3a-4b
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓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 exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Sun River, Montana
- USDA Hardiness Zones: 3a-4b (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 28 (town normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Oct 17 (town normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~172 (town normal, NOAA 1991–2020 Climate Normals)
- Land Area: 1K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. Boundaries: US Census TIGER/Line 2025.
Frequently Asked Questions
What hardiness zone is Sun River, Montana?
Sun River sits in USDA hardiness zones 3a-4b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
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 Mar 31; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 28 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 17 — 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.
When does frost risk typically end in Sun River?
The last hard freeze (28°F) in Sun River typically lands around Apr 28, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
When is the first frost in Sun River?
The first hard freeze (28°F) in Sun River typically arrives around Oct 17, per NOAA 1991–2020 climate normals — the point most tender summer crops finish. Lighter frosts usually reach a couple of weeks earlier, so watch the forecast from late summer on and harvest or cover tender plants before the first cold night.
What vegetables grow in Sun River?
Sun River's zones 3a-4b support a wide range — strong performers include Cherry, Potato, Lentil, Ponderosa Pine, and Rhubarb. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Sun River, really?
Officially, Sun River sits in USDA zones 3a-4b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Sun River?
The federal record around Sun River shows 50 documented sites — 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?
As the season closes around the first 28°F hard freeze near Oct 17 (NOAA 1991–2020 climate normals), a few moves buy time: cover tender plants with floating row cover or an old sheet on still, clear nights, water the soil the afternoon before a freeze so it holds warmth overnight, and harvest frost-tender crops like tomatoes, peppers, and basil before the first hard night. Hardy greens and root crops shrug off light frost and often sweeten after it, so leave them in.
Everything on this page is a Sun River average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.