Kootenai County, in Idaho, sits in USDA hardiness zone 6b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include cabbage, blackberry, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Kootenai County lies within the Idaho Panhandle (North Idaho) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Kootenai County holds more than one microclimate.
Soils and elevations shift across Kootenai 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 Kootenai County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Kootenai County — the short answer
Kootenai County, Idaho: USDA zone 6b, about 186 days between hard freezes, across 792K acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 19
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~186
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 792K 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 Kootenai County's average, not your lot's — a low corner or a tree line moves it. Against Kootenai County's 186-day season, see what your own ground reads.
Heat in Kootenai County
Across a year, Kootenai County accumulates about 1,623 growing degree days above 50°F, about 132 more than the middle Idaho county — ahead of 24 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 Kootenai County
Across Kootenai County, the ground is predominantly Andisols, where Vassar, Kootenai, and Huckle are the most extensive named soil series. The soil is generally well drained with a gravelly ashy silt loam surface. Topsoil pH runs about 6.2–6.7, slightly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Andisols
Drainage
Well drained
Prime farmland
11%
Hydric soils
2%
Soil still varies lot by lot — soil types explained.
How the ground varies across Kootenai County
The USDA soil survey maps 77% of Kootenai County as well drained — but another 14% drains differently: 8% moderately well drained, 4% somewhat excessively drained.
Vassar is the most extensive named soil at 6% of mapped acres, then Kootenai (5%) and Huckle (5%).
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 Kootenai County
Each reading below is measured for Kootenai 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 Kootenai 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 Kootenai County runs about pH 6.2–6.7, 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
MeasuredKootenai County runs about 186 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
MeasuredKootenai 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 Kootenai County is in
Kootenai 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 Kootenai County
We scored all 1,086 plants against Kootenai County's own USDA zone 6b and its own 186-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 Kootenai County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 19 — 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 Kootenai County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Kootenai County
USGS estimates 10,428 lb of Glyphosate on Kootenai County farmland in 2019, its largest by weight, ahead of Bromoxynil (3,422 lb) and 2,4-d (1,946 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 Kootenai County — and how to grow with it.
We checked the federal record across Kootenai County — 701 documented sites across 8 of the 9 source types we track.
The most significant on record: 6 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Kootenai County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Kootenai County
Closest first, across Kootenai County. Listing isn't leaking, and distance isn't exposure.
- COUGAR BAY WATER ASSOCIATIONPFAS · 2.2 mi
- SILVER BEACH MARINAUnderground Storage Tanks · 2.4 mi
- FERNAN RANGER STATIONUnderground Storage Tanks · 2.5 mi
- 50N 02W 30CBC1Nitrate · 2.5 mi
- TESORO # 62133Underground Storage Tanks · 2.7 mi
- BLANE REAL ESTATEUnderground Storage Tanks · 2.7 mi
- PHILLIPS 66 CO #007250Underground Storage Tanks · 2.7 mi
- RUTLEDGE SAWMILLUnderground Storage Tanks · 2.7 mi
- PIGGIES DELI GAS MARTUnderground Storage Tanks · 2.9 mi
- CO-OP SUPPLY CO INC 4Underground Storage Tanks · 2.9 mi
- ROBIDEAUX MOTORS COUnderground Storage Tanks · 3.1 mi
- 50N 03W 06DAA1Nitrate · 3.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Kootenai 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 Kootenai County.
Severity Distribution
across Kootenai County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kootenai County, two things run higher than the national average across Kootenai County — PFAS (8 sites) and Mining (47 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
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 irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Kootenai 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 Kootenai County average
Your land is one point inside Kootenai County
Everything above resolves to Kootenai County as a whole — one PHZM band and one county frost record, read across 792K 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 Kootenai County Average
Kootenai County Average
- ●USDA Zones 6b, averaged across Kootenai County
- ●One soil character for all of Kootenai County
- ●Frost dates read at Kootenai County's scale: Apr 16 to Oct 19
YOUR Parcel
- ✓Your exact zone, not Kootenai County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Kootenai County
Pull a site-specific report for your exact address in Kootenai County, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kootenai County averages can't show:
We read public map data around Kootenai County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kootenai County average
How we know this about Kootenai 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 Kootenai County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Kootenai County
When does frost risk typically end in Kootenai County?
The last hard freeze (28°F) in Kootenai County typically lands around Apr 16, 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 7.
How long is the growing season in Kootenai County?
Measured between 28°F hard freezes, Kootenai County sees about 186 frost-free days — roughly Apr 16 through Oct 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 5, about 151 days.
Is the soil safe to grow vegetables in Kootenai County?
The federal record around Kootenai County runs heavier than most — 701 documented sites, mostly Underground Storage Tanks entries (330), the nearest PFAS record about 2.2 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.
Everything above is measured at Kootenai County's scale — its 6b band and its 186-day season. Your yard writes its own version of Kootenai 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 Kootenai County’s own scale
9 of the readings below were taken at Kootenai County's own scale — its own ~186-day span between 28°F freezes, the 3 most extensive soil series mapped here and 701 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Kootenai County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Kootenai County's own 28°F hard-freeze dates and its ~186-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Kootenai CountyUSDA NRCS SSURGO
- 701 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record about 2.2 miles outFederal environmental registers
- Kootenai County's boundary and the 792,187 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~186-day seasonGrowable Ground crop-matching engine
- Kootenai County sitting wholly inside the Northern RockiesUS EPA Level III Ecoregions
- Open occurrence records documented in Kootenai County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Kootenai 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 Kootenai County — the ~186 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 Kootenai County's 792,187 acreswhy one lot differs from the next →
- Which of those 701 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 Kootenai Countyread your own land →