Turtle Lake, Montana, sits in USDA hardiness zone 6a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
These conditions suit cabbage, blackberry, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Turtle Lake, 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 Turtle Lake 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 Turtle Lake — soil, climate, flood, and parcel records. How we handle your address.
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Turtle Lake — the short answer
Turtle Lake, Montana: USDA zone 6a, about 168 days between hard freezes, across 383 acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~168
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 383 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 6a is Turtle Lake's average, not your lot's — a low corner or a tree line moves it. Against Turtle Lake's 168-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Turtle Lake
Each reading below is measured for Turtle Lake itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTurtle Lake runs about 168 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
MeasuredTurtle Lake sits in USDA hardiness zone 6a.
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 Turtle Lake is in
Turtle Lake sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Turtle Lake's own centroid rather than borrowed from Lake County.
What Grows in Turtle Lake
Every plant below cleared Turtle Lake's own zone 6a and its 168-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Turtle Lake?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 12 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Turtle Lake
Closest first, within ~10 miles of Turtle Lake. Listing isn't leaking, and distance isn't exposure.
- 22N19W18DAA 01Nitrate · 0.7 mi
- POLSON READY MIX CONCRETE INCUnderground Storage Tanks · 1.1 mi
- LES SCHWAB TIRE CENTERBrownfields · 1.5 mi
- SAFEWAY 1646Brownfields · 1.5 mi
- WALMART SUPERCENTER #2607Brownfields · 1.8 mi
- 22N20W25ABA 01Nitrate · 1.8 mi
- O'REILLY AUTO PARTS # 4805Brownfields · 1.9 mi
- QUICKSILVER EXPRESSUnderground Storage Tanks · 2.0 mi
- PACK RIVER LUMBER COUnderground Storage Tanks · 2.2 mi
- SAFEWAY FUEL STATION 1646Underground Storage Tanks · 2.2 mi
- JIMS MARINAUnderground Storage Tanks · 2.2 mi
- MDOT POLSON SITEUnderground Storage Tanks · 2.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Turtle Lake'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 Turtle Lake.
Total Sites
131
within ~10 miles of Turtle Lake
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Turtle Lake
Severity Distribution
within ~10 miles of Turtle Lake
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Turtle Lake, Nitrate runs higher than the national average — 42 sites within ~10 miles of Turtle Lake. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
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 Turtle Lake
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 Turtle Lake average
Your land is one point inside Turtle Lake
Everything above resolves to Turtle Lake as a whole — one PHZM band and one 28°F frost record, read across 383 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 Turtle Lake Average
Turtle Lake Average
- ●USDA Zones 6a, averaged across Turtle Lake
- ●One soil character for all of Turtle Lake
- ●Frost dates read at Turtle Lake's scale: Apr 27 to Oct 12
YOUR Parcel
- ✓Your exact zone, not Turtle Lake's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Turtle Lake
Pull a site-specific report for your exact address in Turtle Lake, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Turtle Lake averages can't show:
We read public map data around Turtle Lake — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Turtle Lake average
How we know this about Turtle Lake
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 Turtle Lake’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 Turtle Lake
When does frost risk typically end in Turtle Lake?
The last hard freeze (28°F) in Turtle Lake typically lands around Apr 27, 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 18.
When is the first frost in Turtle Lake?
The first hard freeze (28°F) in Turtle Lake typically arrives around Oct 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 28, so the watching starts about Sep 12 — about 168 days after the spring freeze cleared.
How long is the growing season in Turtle Lake?
Measured between 28°F hard freezes, Turtle Lake sees about 168 frost-free days — roughly Apr 27 through Oct 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Sep 28, about 133 days.
Is the soil safe to grow vegetables in Turtle Lake?
The federal record around Turtle Lake is a meaningful one — 131 documented sites, mostly Underground Storage Tanks entries (60), the nearest Nitrate record about 0.7 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 Turtle Lake?
From about Sep 12 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 12 (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 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Turtle Lake's scale — its 6a band and its 168-day season. Your yard writes its own version of Turtle Lake'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 Turtle Lake’s own scale
6 of the readings below were taken at Turtle Lake's own scale — its own ~168-day season between 28°F freezes, the 383 acres it covers and 131 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Turtle Lake's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Turtle Lake's own 28°F hard-freeze dates, about Apr 27 and Oct 12 and the ~168-day span between themNOAA 1991–2020 Climate Normals
- 131 documented contamination sites on the federal record near Turtle Lake, the closest Nitrate record about 0.7 miles out from the town centreFederal environmental registers
- Turtle Lake's boundary and the 383 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~168-day seasonGrowable Ground crop-matching engine
- The ecoregion at Turtle Lake's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Turtle Lake's 383 acres read through its county's SSURGO summaryfrom Lake County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lake 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 Lake County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Turtle Lake's 383 acreswhy one lot differs from the next →
- Which side of Turtle Lake you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 383 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.7 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 Turtle Lake-wide figureread your own land →
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