Horizon 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.
Growers here do well with cabbage, cranberry, cilantro, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Horizon 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 Horizon 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 Horizon Colony — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Horizon Colony — the short answer
Horizon Colony, Montana: USDA zone 4a, about 146 days between hard freezes, across 241 acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~146
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 241 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 Horizon Colony's average, not your lot's — a low corner or a tree line moves it. Against Horizon Colony's 146-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Horizon Colony
Each reading below is measured for Horizon Colony itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHorizon Colony runs about 146 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredHorizon 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 Horizon Colony is in
Horizon Colony sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Horizon Colony's own centroid rather than borrowed from Glacier County.
What Grows in Horizon Colony
Every plant below cleared Horizon Colony's own zone 4a and its 146-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Horizon Colony?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 29 — long-season crops need about 90 days of runway, quick greens only 30. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
What's on the federal record near Horizon Colony
Closest first, within ~10 miles of Horizon Colony. Listing isn't leaking, and distance isn't exposure.
- HORIZON COLONY CAFOCAFO · 1600 ft
- 34N05W03BB 01Nitrate · 1.9 mi
- 35N05W34AB 01Nitrate · 2.5 mi
- 34N05W20BB 01Nitrate · 3.4 mi
- 34N05W29DA 01Nitrate · 3.7 mi
- H ARTHUR TOMSHECKUnderground Storage Tanks · 4.1 mi
- 34N05W35DC 01Nitrate · 4.1 mi
- 35N05W15DC 01Nitrate · 4.7 mi
- RUMNEY RANCHUnderground Storage Tanks · 5.0 mi
- 34N06W12CC 01Nitrate · 5.1 mi
- 35N05W20BB 02Nitrate · 5.4 mi
- 34N06W14DD 01Nitrate · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Horizon 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 Horizon Colony.
Total Sites
117
within ~10 miles of Horizon Colony
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Horizon Colony
Severity Distribution
within ~10 miles of Horizon Colony
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Horizon Colony, Nitrate runs higher than the national average — 50 sites within ~10 miles of Horizon Colony. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Horizon 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 Horizon Colony average
Your land is one point inside Horizon Colony
Everything above resolves to Horizon Colony as a whole — one PHZM band and one 28°F frost record, read across 241 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 Horizon Colony Average
Horizon Colony Average
- ●USDA Zones 4a, averaged across Horizon Colony
- ●One soil character for all of Horizon Colony
- ●Frost dates read at Horizon Colony's scale: May 6 to Sep 29
YOUR Parcel
- ✓Your exact zone, not Horizon Colony's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Horizon Colony
Pull a site-specific report for your exact address in Horizon Colony, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Horizon Colony averages can't show:
We read public map data around Horizon Colony — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Horizon Colony average
How we know this about Horizon 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 Horizon 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 Horizon Colony
When does frost risk typically end in Horizon Colony?
The last hard freeze (28°F) in Horizon Colony typically lands around May 6, 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 27.
When is the first frost in Horizon Colony?
The first hard freeze (28°F) in Horizon Colony typically arrives around Sep 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 15, so the watching starts about Aug 30 — about 146 days after the spring freeze cleared.
How long is the growing season in Horizon Colony?
Measured between 28°F hard freezes, Horizon Colony sees about 146 frost-free days — roughly May 6 through Sep 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 27 to Sep 15, about 111 days.
Is the soil safe to grow vegetables in Horizon Colony?
The federal record around Horizon Colony is a meaningful one — 117 documented sites, mostly Nitrate entries (50), the nearest CAFO record about 0.3 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 gardeners stretch the season in Horizon Colony?
With about 146 frost-free days between hard freezes, Horizon Colony rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 174 to 202 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 6 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Horizon Colony's scale — its 4a band and its 146-day season. Your yard writes its own version of Horizon 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 Horizon Colony’s own scale
6 of the readings below were taken at Horizon Colony's own scale — its own ~146-day season between 28°F freezes, the 241 acres it covers and 117 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Horizon Colony's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Horizon Colony's own 28°F hard-freeze dates, about May 6 and Sep 29 and the ~146-day span between themNOAA 1991–2020 Climate Normals
- 117 documented contamination sites on the federal record near Horizon Colony, the closest CAFO record about 0.3 miles out from the town centreFederal environmental registers
- Horizon Colony's boundary and the 241 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~146-day seasonGrowable Ground crop-matching engine
- The ecoregion at Horizon 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 Horizon Colony's 241 acres read through its county's SSURGO summaryfrom Glacier County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Glacier 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 Glacier County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Horizon Colony's 241 acreswhy one lot differs from the next →
- Which side of Horizon 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 241 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 Horizon Colony-wide figureread your own land →