Clearwater County, in Idaho, sits in USDA hardiness zone 6b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include cabbage, blackberry, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Clearwater County holds more than one microclimate.
Soils and elevations shift across Clearwater County, so your frost dates and drainage aren't the county average. 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 Clearwater County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Clearwater County — the short answer
Clearwater County, Idaho: USDA zone 6b, about 162 days between hard freezes, across 1.6M acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 3
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 12
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~162
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.6M acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 6b is Clearwater County's average, not your lot's — a low corner or a tree line moves it. Against Clearwater County's 162-day season, see what your own ground reads.
Heat in Clearwater County
Across a year, Clearwater County accumulates about 1,157 growing degree days above 50°F, about 334 fewer than the middle Idaho county — ahead of 12 of Idaho’s 44 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Clearwater County
Across Clearwater County, the ground is predominantly Andisols, where Brodeer, Dullaxe, and Grangemont are the most extensive named soil series. The soil is generally well drained with a ashy silt loam surface. Topsoil pH runs about 5.8–6.5, slightly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Andisols
Drainage
Well drained
Prime farmland
0%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Clearwater County
The USDA soil survey maps 84% of Clearwater County as well drained — but another 12% drains differently: 10% moderately well drained, 2% somewhat excessively drained.
Brodeer is the most extensive named soil at 3% of mapped acres, then Dullaxe (3%) and Grangemont (2%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Clearwater County
Each reading below is measured for Clearwater County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Clearwater County are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Clearwater County runs about pH 5.8–6.5, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredClearwater County runs about 162 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
MeasuredClearwater County sits in USDA hardiness zone 6b.
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 Clearwater County is in
Clearwater County sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. One consistent ecological setting across the whole county.
What Grows in Clearwater County
We scored all 1,086 plants against Clearwater County's own USDA zone 6b and its own 162-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Idaho profile.
Is it too late to plant in Clearwater County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 3 (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. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
Documented around Clearwater County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Clearwater County
USGS estimates 7,734 lb of Glyphosate on Clearwater County farmland in 2019, its largest by weight, ahead of Bromoxynil (2,216 lb) and Metolachlor-s (1,645 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Clearwater County — and how to grow with it.
We checked the federal record across Clearwater County — 113 documented sites across 7 of the 9 source types we track.
The most significant on record: 6 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Clearwater County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Clearwater County
Closest first, across Clearwater County. Listing isn't leaking, and distance isn't exposure.
- Name UnknownMining · 0.6 mi
- Oxford ProspectMining · 4.3 mi
- PIERCE CITY OFPFAS · 9.5 mi
- FINKE LOGGING COUnderground Storage Tanks · 11.5 mi
- POTLATCH LOG YARD SITEToxics Release Inventory · 13.0 mi
- JAYPE PLYWOODUnderground Storage Tanks · 13.2 mi
- PIERCE WORK CENTERUnderground Storage Tanks · 14.0 mi
- WEITAS GUARD STATIONUnderground Storage Tanks · 14.0 mi
- HUNT OIL COMPANY (1)Underground Storage Tanks · 14.0 mi
- THE OZARK GROUPSuperfund · 14.2 mi
- PIERCE MINI MARTUnderground Storage Tanks · 14.2 mi
- GLEN WADDELLUnderground Storage Tanks · 14.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Clearwater County'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 Clearwater County.
Total Sites
113
across Clearwater County
Risk Level
Elevated
Highest-severity
6 Superfund sites (none NPL-listed)
Sources Checked
across Clearwater County
Severity Distribution
across Clearwater County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clearwater County, two things run higher than the national average across Clearwater County — Mining (30 sites) and Superfund (6 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Clearwater County
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 Clearwater County average
Your land is one point inside Clearwater County
Everything above resolves to Clearwater County as a whole — one PHZM band and one county frost record, read across 1.6M 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 county 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 county average.
Your Lot vs the Clearwater County Average
Clearwater County Average
- ●USDA Zones 6b, averaged across Clearwater County
- ●One soil character for all of Clearwater County
- ●Frost dates read at Clearwater County's scale: May 3 to Oct 12
YOUR Parcel
- ✓Your exact zone, not Clearwater County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Clearwater County
Pull a site-specific report for your exact address in Clearwater County, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clearwater County averages can't show:
We read public map data around Clearwater County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clearwater County average
How we know this about Clearwater County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Clearwater County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Clearwater County
When does frost risk typically end in Clearwater County?
The last hard freeze (28°F) in Clearwater County typically lands around May 3, 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 24.
How long is the growing season in Clearwater County?
Measured between 28°F hard freezes, Clearwater County sees about 162 frost-free days — roughly May 3 through Oct 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 24 to Sep 28, about 127 days.
Is the soil safe to grow vegetables in Clearwater County?
The federal record around Clearwater County is a meaningful one — 113 documented sites, mostly Underground Storage Tanks entries (38), the nearest Mining record about 0.6 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.
Everything above is measured at Clearwater County's scale — its 6b band and its 162-day season. Your yard writes its own version of Clearwater County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Idaho's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Clearwater County’s own scale
9 of the readings below were taken at Clearwater County's own scale — its own ~162-day span between 28°F freezes, the 3 most extensive soil series mapped here and 113 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Clearwater County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Clearwater County's own 28°F hard-freeze dates and its ~162-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Clearwater CountyUSDA NRCS SSURGO
- 113 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 0.6 miles outFederal environmental registers
- Clearwater County's boundary and the 1,572,679 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~162-day seasonGrowable Ground crop-matching engine
- Clearwater County sitting wholly inside the Northern RockiesUS EPA Level III Ecoregions
- Open occurrence records documented in Clearwater County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Clearwater County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
What this page can’t tell you
- How the season shifts across Clearwater County — the ~162 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Clearwater County's 1,572,679 acreswhy one lot differs from the next →
- Which of those 113 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Clearwater Countyread your own land →