Rimrock Colony, Montana, sits in USDA hardiness zone 4a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
On paper, cabbage, cranberry, turkish rocket, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Rimrock Colony, 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 Rimrock Colony 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 Rimrock Colony — soil, climate, flood, and parcel records. How we handle your address.
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Rimrock Colony — the short answer
Rimrock Colony, Montana: USDA zone 4a, about 150 days between hard freezes, across 201 acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~150
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 201 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 Rimrock Colony's average, not your lot's — a low corner or a tree line moves it. Against Rimrock Colony's 150-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rimrock Colony
Each reading below is measured for Rimrock Colony itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRimrock Colony runs about 150 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
MeasuredRimrock Colony 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 Rimrock Colony is in
Rimrock Colony sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Rimrock Colony's own centroid rather than borrowed from Toole County.
What Grows in Rimrock Colony
Every plant below cleared Rimrock Colony's own zone 4a and its 150-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Rimrock Colony?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Apr 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 2 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Rimrock Colony
Closest first, within ~10 miles of Rimrock Colony. Listing isn't leaking, and distance isn't exposure.
- RIMROCK COLONYCAFO · 1600 ft
- 36N04W14AC 01Nitrate · 1.1 mi
- 36N04W22DC 01Nitrate · 2.6 mi
- 37N04W27CB 01Nitrate · 2.9 mi
- 36N03W19CC 01Nitrate · 3.1 mi
- 37N03W30ACC 01Nitrate · 3.5 mi
- 36N04W35AB 01Nitrate · 3.8 mi
- 37N03W21DB 01Nitrate · 5.5 mi
- 37N03W21ACB 01Nitrate · 5.7 mi
- 36N05W14AC 01Nitrate · 5.7 mi
- 37N04W12DB 01Nitrate · 5.7 mi
- HILLSIDE COLONY CAFOCAFO · 5.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rimrock Colony'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 Rimrock Colony.
Total Sites
65
within ~10 miles of Rimrock Colony
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Rimrock Colony
Severity Distribution
within ~10 miles of Rimrock Colony
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rimrock Colony, two things run higher than the national average within ~10 miles of Rimrock Colony — CAFO (3 sites) and Nitrate (50 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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 Rimrock Colony
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 Rimrock Colony average
Your land is one point inside Rimrock Colony
Everything above resolves to Rimrock Colony as a whole — one PHZM band and one 28°F frost record, read across 201 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 Rimrock Colony Average
Rimrock Colony Average
- ●USDA Zones 4a, averaged across Rimrock Colony
- ●One soil character for all of Rimrock Colony
- ●Frost dates read at Rimrock Colony's scale: May 5 to Oct 2
YOUR Parcel
- ✓Your exact zone, not Rimrock Colony's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rimrock Colony
Pull a site-specific report for your exact address in Rimrock Colony, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rimrock Colony averages can't show:
We read public map data around Rimrock Colony — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rimrock Colony average
How we know this about Rimrock Colony
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 Rimrock Colony’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 Rimrock Colony
When does frost risk typically end in Rimrock Colony?
The last hard freeze (28°F) in Rimrock Colony typically lands around May 5, 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 26.
When is the first frost in Rimrock Colony?
The first hard freeze (28°F) in Rimrock Colony typically arrives around Oct 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 18, so the watching starts about Sep 2 — about 150 days after the spring freeze cleared.
How long is the growing season in Rimrock Colony?
Measured between 28°F hard freezes, Rimrock Colony sees about 150 frost-free days — roughly May 5 through Oct 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 18, about 115 days.
Is the soil safe to grow vegetables in Rimrock Colony?
The federal record around Rimrock Colony shows 65 documented sites, mostly Nitrate entries (50), the nearest CAFO record about 0.3 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 Rimrock Colony?
From about Sep 2 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 2 (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 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Rimrock Colony's scale — its 4a band and its 150-day season. Your yard writes its own version of Rimrock Colony'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 Rimrock Colony’s own scale
6 of the readings below were taken at Rimrock Colony's own scale — its own ~150-day season between 28°F freezes, the 201 acres it covers and 65 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rimrock Colony's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Rimrock Colony's own 28°F hard-freeze dates, about May 5 and Oct 2 and the ~150-day span between themNOAA 1991–2020 Climate Normals
- 65 documented contamination sites on the federal record near Rimrock Colony, the closest CAFO record about 0.3 miles out from the town centreFederal environmental registers
- Rimrock Colony's boundary and the 201 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~150-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rimrock Colony's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rimrock Colony's 201 acres read through its county's SSURGO summaryfrom Toole County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Toole 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 Toole County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rimrock Colony's 201 acreswhy one lot differs from the next →
- Which side of Rimrock Colony you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 201 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest CAFO record about 0.3 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 Rimrock Colony-wide figureread your own land →
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