Sunnybrook Colony, Montana, sits in USDA hardiness zone 4a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — cabbage, cranberry, turkish rocket, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Sunnybrook 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 Sunnybrook 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 Sunnybrook Colony — soil, climate, flood, and parcel records. How we handle your address.
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Sunnybrook Colony — the short answer
Sunnybrook Colony, Montana: USDA zone 4a, about 155 days between hard freezes, across 150 acres of town.
- USDA zone
- 4a
- 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 3
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~155
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 150 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 Sunnybrook Colony's average, not your lot's — a low corner or a tree line moves it. Against Sunnybrook Colony's 155-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sunnybrook Colony
Each reading below is measured for Sunnybrook Colony itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSunnybrook Colony runs about 155 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
MeasuredSunnybrook 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 Sunnybrook Colony is in
Sunnybrook Colony sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Sunnybrook Colony's own centroid rather than borrowed from Chouteau County.
What Grows in Sunnybrook Colony
Every plant below cleared Sunnybrook Colony's own zone 4a and its 155-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Sunnybrook Colony?
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 3 — 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 Sunnybrook Colony
Closest first, within ~10 miles of Sunnybrook Colony. Listing isn't leaking, and distance isn't exposure.
- UPHAM FARM INCUnderground Storage Tanks · 7.8 mi
- 28N02E31BCCC01Nitrate · 8.9 mi
Measured from Sunnybrook 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 Sunnybrook Colony.
Total Sites
3
within ~10 miles of Sunnybrook Colony
Risk Level
Low
Highest-severity
2 nitrate monitoring sites
Severity Distribution
within ~10 miles of Sunnybrook Colony
Highest-Severity Sites
Know Before You Grow
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
Check your specific parcel in Sunnybrook 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 Sunnybrook Colony average
Your land is one point inside Sunnybrook Colony
Everything above resolves to Sunnybrook Colony as a whole — one PHZM band and one 28°F frost record, read across 150 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 Sunnybrook Colony Average
Sunnybrook Colony Average
- ●USDA Zones 4a, averaged across Sunnybrook Colony
- ●One soil character for all of Sunnybrook Colony
- ●Frost dates read at Sunnybrook Colony's scale: May 1 to Oct 3
YOUR Parcel
- ✓Your exact zone, not Sunnybrook Colony's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sunnybrook Colony
Pull a site-specific report for your exact address in Sunnybrook Colony, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sunnybrook Colony averages can't show:
We read public map data around Sunnybrook Colony — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sunnybrook Colony average
How we know this about Sunnybrook 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 Sunnybrook 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 Sunnybrook Colony
When does frost risk typically end in Sunnybrook Colony?
The last hard freeze (28°F) in Sunnybrook Colony 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 Sunnybrook Colony?
The first hard freeze (28°F) in Sunnybrook Colony typically arrives around Oct 3, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 19, so the watching starts about Sep 3 — about 155 days after the spring freeze cleared.
How long is the growing season in Sunnybrook Colony?
Measured between 28°F hard freezes, Sunnybrook Colony sees about 155 frost-free days — roughly May 1 through Oct 3, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 22 to Sep 19, about 120 days.
Is the soil safe to grow vegetables in Sunnybrook Colony?
The federal record around Sunnybrook Colony is light — 3 documented sites across the 9 federal source types we checked, mostly Nitrate entries (2), the nearest Underground Storage Tanks record about 7.8 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Sunnybrook Colony?
From about Sep 3 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 3 (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 3. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sunnybrook Colony's scale — its 4a band and its 155-day season. Your yard writes its own version of Sunnybrook 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 Sunnybrook Colony’s own scale
6 of the readings below were taken at Sunnybrook Colony's own scale — its own ~155-day season between 28°F freezes, the 150 acres it covers and 3 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Sunnybrook Colony's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Sunnybrook Colony's own 28°F hard-freeze dates, about May 1 and Oct 3 and the ~155-day span between themNOAA 1991–2020 Climate Normals
- 3 documented contamination sites on the federal record near Sunnybrook Colony, the closest Underground Storage Tanks record about 7.8 miles out from the town centreFederal environmental registers
- Sunnybrook Colony's boundary and the 150 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~155-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sunnybrook 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 Sunnybrook Colony's 150 acres read through its county's SSURGO summaryfrom Chouteau County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Chouteau 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 Chouteau County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sunnybrook Colony's 150 acreswhy one lot differs from the next →
- Which side of Sunnybrook 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 150 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 7.8 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 Sunnybrook Colony-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaSunnybrook Colony sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides