Post Falls, Idaho, sits in USDA hardiness zone 6b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include cabbage, blackberry, california poppy, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Post Falls, 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 Post Falls 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 Post Falls — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Post Falls — the short answer
Post Falls, Idaho: USDA zone 6b, about 192 days between hard freezes, across 12K acres of city.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~192
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 12K 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 6b is Post Falls's average, not your lot's — a low corner or a tree line moves it. Against Post Falls's 192-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Post Falls
Each reading below is measured for Post Falls itself — here is what it means for a garden here, and the move an experienced grower makes about it.

Season length
MeasuredPost Falls runs about 192 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
MeasuredPost Falls 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 Post Falls is in
Post Falls sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Post Falls's own centroid rather than borrowed from Kootenai County.
What Grows in Post Falls
Every plant below cleared Post Falls's own zone 6b and its 192-day season. Each card opens that plant's Idaho profile. How we score.






























Is it too late to plant in Post Falls?
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 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 23 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Post Falls
Closest first, within ~10 miles of Post Falls. Listing isn't leaking, and distance isn't exposure.
- Post Falls MazdaUnderground Storage Tanks · 1400 ft
- AUSBURN AUTO REPAIRUnderground Storage Tanks · 0.5 mi
- POST FALLS SD 273 BUS GARAGEBrownfields · 0.6 mi
- POST FALLS GENERATOR (1280-BO2)Underground Storage Tanks · 0.6 mi
- 51N 05W 35CAC1Nitrate · 0.7 mi
- POST FALLS GAS MARTUnderground Storage Tanks · 0.7 mi
- POST FALLS EXXONUnderground Storage Tanks · 0.7 mi
- PERFECTION TIREUnderground Storage Tanks · 0.8 mi
- POST FALLS THRIFTY MARTUnderground Storage Tanks · 0.8 mi
- POST FALLS JIFI STOPUnderground Storage Tanks · 0.8 mi
- WALGREENS STORE #7949Brownfields · 0.8 mi
- JACKPOT FOOD MARTUnderground Storage Tanks · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Post Falls'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 Post Falls.
Sources Checked
within ~10 miles of Post Falls
Severity Distribution
within ~10 miles of Post Falls
Highest-Severity Sites

A note from Gnorman
What an experienced grower watches for around here
In and around Post Falls, two things run higher than the national average within ~10 miles of Post Falls — PFAS (6 sites) and Toxics Release Inventory (36 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Post Falls
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 Post Falls average
Your land is one point inside Post Falls
Everything above resolves to Post Falls as a whole — one PHZM band and one 28°F frost record, read across 12K 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 city 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 Post Falls Average
Post Falls Average
- ●USDA Zones 6b, averaged across Post Falls
- ●One soil character for all of Post Falls
- ●Frost dates read at Post Falls's scale: Apr 14 to Oct 23
YOUR Parcel
- ✓Your exact zone, not Post Falls's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Post Falls
Pull a site-specific report for your exact address in Post Falls, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Post Falls averages can't show:
We read public map data around Post Falls — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Post Falls average
How we know this about Post Falls
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Post Falls’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 city grain anywhere on this page — there is no city-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 Post Falls
When does frost risk typically end in Post Falls?
The last hard freeze (28°F) in Post Falls typically lands around Apr 14, 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 5.
When is the first frost in Post Falls?
The first hard freeze (28°F) in Post Falls typically arrives around Oct 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 9, so the watching starts about Sep 23 — about 192 days after the spring freeze cleared.
How long is the growing season in Post Falls?
Measured between 28°F hard freezes, Post Falls sees about 192 frost-free days — roughly Apr 14 through Oct 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 5 to Oct 9, about 157 days.
Is the soil safe to grow vegetables in Post Falls?
The federal record around Post Falls is a meaningful one — 571 documented sites, mostly Underground Storage Tanks entries (295), the nearest Underground Storage Tanks 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 I protect my plants from frost in Post Falls?
From about Sep 23 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 23 (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 23. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Post Falls's scale — its 6b band and its 192-day season. Your yard writes its own version of Post Falls'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 Post Falls’s own scale
6 of the readings below were taken at Post Falls's own scale — its own ~192-day season between 28°F freezes, the 12,234 acres it covers and 571 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Post Falls's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Post Falls's own 28°F hard-freeze dates, about Apr 14 and Oct 23 and the ~192-day span between themNOAA 1991–2020 Climate Normals
- 571 documented contamination sites on the federal record near Post Falls, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Post Falls's boundary and the 12,234 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~192-day seasonGrowable Ground crop-matching engine
- The ecoregion at Post Falls's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Post Falls's 12,234 acres read through its county's SSURGO summaryfrom Kootenai County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Kootenai County
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Kootenai County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Post Falls's 12,234 acreswhy one lot differs from the next →
- Which side of Post Falls you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 12,234 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Post Falls-wide figureread your own land →
More in Idaho
Growing region
Nearby growing guides
