Twin Creeks, Montana, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Among the crops suited to this profile: cabbage, cranberry, lavender, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Twin Creeks, 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 Twin Creeks 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 Twin Creeks — soil, climate, flood, and parcel records. How we handle your address.
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Twin Creeks — the short answer
Twin Creeks, Montana: USDA zone 5a, about 136 days between hard freezes, across 716 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~136
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 716 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 5a is Twin Creeks's average, not your lot's — a low corner or a tree line moves it. Against Twin Creeks's 136-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Twin Creeks
Each reading below is measured for Twin Creeks itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTwin Creeks runs about 136 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
MeasuredTwin Creeks sits in USDA hardiness zone 5a.
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 Twin Creeks is in
Twin Creeks sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Twin Creeks's own centroid rather than borrowed from Missoula County.
What Grows in Twin Creeks
Every plant below cleared Twin Creeks's own zone 5a and its 136-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Twin Creeks?
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 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 25 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Twin Creeks
Closest first, within ~10 miles of Twin Creeks. Listing isn't leaking, and distance isn't exposure.
- PRECIOUS METALS PLATING HUDSuperfund · 3.4 mi
- ChesterMining · 4.8 mi
- Juniper ProspectMining · 5.6 mi
- GowrieMining · 6.6 mi
- STIMSON LUMBER CO BONNER OPERATIONToxics Release Inventory · 6.7 mi
- STIMSON LUMBER CO BONNER OPERATIONBrownfields · 6.7 mi
- FORMER MWRR CLINTONUnderground Storage Tanks · 6.7 mi
- WESTON RANCHES INCUnderground Storage Tanks · 6.7 mi
- MDOT CLINTON SITEUnderground Storage Tanks · 6.7 mi
- BN CLINTON MICROWAVEUnderground Storage Tanks · 6.7 mi
- JMBC INCUnderground Storage Tanks · 6.8 mi
- Copper KingMining · 6.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Twin Creeks'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 Twin Creeks.
Sources Checked
within ~10 miles of Twin Creeks
Severity Distribution
within ~10 miles of Twin Creeks
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Twin Creeks, Mining runs higher than the national average — 50 sites within ~10 miles of Twin Creeks. That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Twin Creeks
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 Twin Creeks average
Your land is one point inside Twin Creeks
Everything above resolves to Twin Creeks as a whole — one PHZM band and one 28°F frost record, read across 716 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 Twin Creeks Average
Twin Creeks Average
- ●USDA Zones 5a, averaged across Twin Creeks
- ●One soil character for all of Twin Creeks
- ●Frost dates read at Twin Creeks's scale: May 12 to Sep 25
YOUR Parcel
- ✓Your exact zone, not Twin Creeks's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Twin Creeks
Pull a site-specific report for your exact address in Twin Creeks, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Twin Creeks averages can't show:
We read public map data around Twin Creeks — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Twin Creeks average
How we know this about Twin Creeks
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 Twin Creeks’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 Twin Creeks
When does frost risk typically end in Twin Creeks?
The last hard freeze (28°F) in Twin Creeks typically lands around May 12, 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 Jun 2.
When is the first frost in Twin Creeks?
The first hard freeze (28°F) in Twin Creeks typically arrives around Sep 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 11, so the watching starts about Aug 26 — about 136 days after the spring freeze cleared.
How long is the growing season in Twin Creeks?
Measured between 28°F hard freezes, Twin Creeks sees about 136 frost-free days — roughly May 12 through Sep 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 2 to Sep 11, about 101 days.
Is the soil safe to grow vegetables in Twin Creeks?
The federal record around Twin Creeks runs heavier than most — 90 documented sites, mostly Mining entries (50), the nearest Superfund record about 3.4 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do gardeners stretch the season in Twin Creeks?
With about 136 frost-free days between hard freezes, Twin Creeks 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 164 to 192 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 12 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Twin Creeks's scale — its 5a band and its 136-day season. Your yard writes its own version of Twin Creeks'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 Twin Creeks’s own scale
6 of the readings below were taken at Twin Creeks's own scale — its own ~136-day season between 28°F freezes, the 716 acres it covers and 90 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Twin Creeks's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Twin Creeks's own 28°F hard-freeze dates, about May 12 and Sep 25 and the ~136-day span between themNOAA 1991–2020 Climate Normals
- 90 documented contamination sites on the federal record near Twin Creeks, the closest Superfund record about 3.4 miles out from the town centreFederal environmental registers
- Twin Creeks's boundary and the 716 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~136-day seasonGrowable Ground crop-matching engine
- The ecoregion at Twin Creeks's own centroid, the Middle RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Twin Creeks's 716 acres read through its county's SSURGO summaryfrom Missoula County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Missoula 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 Missoula County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Twin Creeks's 716 acreswhy one lot differs from the next →
- Which side of Twin Creeks you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 716 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Superfund record about 3.4 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 Twin Creeks-wide figureread your own land →
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