Sun Prairie, Montana, sits in USDA hardiness zone 4b — 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 Prairie, 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 Prairie 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 Prairie — soil, climate, flood, and parcel records. How we handle your address.
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Sun Prairie — the short answer
Sun Prairie, Montana: USDA zone 4b, about 161 days between hard freezes, across 3K acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~161
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 4b is Sun Prairie's average, not your lot's — a low corner or a tree line moves it. Against Sun Prairie'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 Prairie
Each reading below is measured for Sun Prairie itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSun Prairie 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 Prairie sits in USDA hardiness zone 4b.
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 Prairie is in
Sun Prairie sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Sun Prairie's own centroid rather than borrowed from Cascade County.
What Grows in Sun Prairie
Every plant below cleared Sun Prairie's own zone 4b and its 161-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Sun Prairie?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Apr 3; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 1 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 9 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Sun Prairie
Closest first, within ~10 miles of Sun Prairie. Listing isn't leaking, and distance isn't exposure.
- CASCADE COUNTY FLEET MAINTENANCE SHOPBrownfields · 0.9 mi
- 21N02E34ABCC01Nitrate · 1.2 mi
- 20N02E03BAAD01Nitrate · 1.4 mi
- GAS N SHOP 2Underground Storage Tanks · 1.4 mi
- WESTERN LIVESTOCK AUCTIONCAFO · 1.7 mi
- VAUGHN TRUCK STOPUnderground Storage Tanks · 2.8 mi
- EMERALD SERVICES INC - GREAT FALLS FACILITYBrownfields · 2.9 mi
- GLACIER GATEWAYUnderground Storage Tanks · 3.1 mi
- VAUGHN JUNCTION RADIO BLDGUnderground Storage Tanks · 3.2 mi
- 20N02E01CCCB01Nitrate · 3.2 mi
- VALLEY COUNTRY STORE INCUnderground Storage Tanks · 3.3 mi
- 20N02E01AABA01Nitrate · 3.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sun Prairie'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 Prairie.
Total Sites
338
within ~10 miles of Sun Prairie
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Sun Prairie
Severity Distribution
within ~10 miles of Sun Prairie
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sun Prairie, two things run higher than the national average within ~10 miles of Sun Prairie — CAFO (3 sites) and Underground Storage Tanks (214 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Sun Prairie
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 Prairie average
Your land is one point inside Sun Prairie
Everything above resolves to Sun Prairie as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Prairie Average
Sun Prairie Average
- ●USDA Zones 4b, averaged across Sun Prairie
- ●One soil character for all of Sun Prairie
- ●Frost dates read at Sun Prairie's scale: May 1 to Oct 9
YOUR Parcel
- ✓Your exact zone, not Sun Prairie's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sun Prairie
Pull a site-specific report for your exact address in Sun Prairie, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sun Prairie averages can't show:
We read public map data around Sun Prairie — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sun Prairie average
How we know this about Sun Prairie
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 Prairie’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 Prairie
When does frost risk typically end in Sun Prairie?
The last hard freeze (28°F) in Sun Prairie typically lands around May 1, 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 22.
When is the first frost in Sun Prairie?
The first hard freeze (28°F) in Sun Prairie typically arrives around Oct 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 25, so the watching starts about Sep 9 — about 161 days after the spring freeze cleared.
How long is the growing season in Sun Prairie?
Measured between 28°F hard freezes, Sun Prairie sees about 161 frost-free days — roughly May 1 through Oct 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 25, about 126 days.
Is the soil safe to grow vegetables in Sun Prairie?
The federal record around Sun Prairie is a meaningful one — 338 documented sites, mostly Underground Storage Tanks entries (214), the nearest Brownfields record about 0.9 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Sun Prairie?
From about Sep 9 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 9 (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 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sun Prairie's scale — its 4b band and its 161-day season. Your yard writes its own version of Sun Prairie'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 Prairie’s own scale
6 of the readings below were taken at Sun Prairie's own scale — its own ~161-day season between 28°F freezes, the 3,390 acres it covers and 338 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Sun Prairie's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Sun Prairie's own 28°F hard-freeze dates, about May 1 and Oct 9 and the ~161-day span between themNOAA 1991–2020 Climate Normals
- 338 documented contamination sites on the federal record near Sun Prairie, the closest Brownfields record about 0.9 miles out from the town centreFederal environmental registers
- Sun Prairie's boundary and the 3,390 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~161-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sun Prairie'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 Prairie's 3,390 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 Prairie's 3,390 acreswhy one lot differs from the next →
- Which side of Sun Prairie you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,390 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.9 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 Prairie-wide figureread your own land →