State Line, Idaho, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
On paper, cabbage, pawpaw, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in State Line, 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 State Line 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 State Line — soil, climate, flood, and parcel records. How we handle your address.
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State Line — the short answer
State Line, Idaho: USDA zone 7a, about 196 days between hard freezes, across 70 acres of city.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 24
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~196
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 70 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 7a is State Line's average, not your lot's — a low corner or a tree line moves it. Against State Line's 196-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in State Line
Each reading below is measured for State Line itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredState Line runs about 196 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
MeasuredState Line sits in USDA hardiness zone 7a.
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 State Line is in
State Line sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at State Line's own centroid rather than borrowed from Kootenai County.
What Grows in State Line
Every plant below cleared State Line's own zone 7a and its 196-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in State Line?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 11 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 24 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near State Line
Closest first, within ~10 miles of State Line. Listing isn't leaking, and distance isn't exposure.
- LIBERTY STOP N GOUnderground Storage Tanks · 700 ft
- AmerimartUnderground Storage Tanks · 1000 ft
- A1 Smoke ShopUnderground Storage Tanks · 1600 ft
- CABELAS STORE 025Brownfields · 1700 ft
- WALMART SUPERCENTER #4395Brownfields · 2100 ft
- 26N/46E-31M06Nitrate · 2400 ft
- 26N/46E-31M04Nitrate · 2600 ft
- 26N/46E-31M05Nitrate · 2600 ft
- 26N/46E-31M03Nitrate · 0.5 mi
- UNITED PARCEL SERVICE - POST FALLS - IDPFLBrownfields · 0.7 mi
- ID NAT GUARD/POST FALLS ARMORY FMS SUB 1Underground Storage Tanks · 0.7 mi
- JACKLIN SEED COUnderground Storage Tanks · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from State Line'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 State Line.
Sources Checked
within ~10 miles of State Line
Severity Distribution
within ~10 miles of State Line
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around State Line, two things run higher than the national average within ~10 miles of State Line — PFAS (9 sites) and Toxics Release Inventory (53 sites). That's not a problem with your land — it's information about it.
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 State Line
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 State Line average
Your land is one point inside State Line
Everything above resolves to State Line as a whole — one PHZM band and one 28°F frost record, read across 70 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 State Line Average
State Line Average
- ●USDA Zones 7a, averaged across State Line
- ●One soil character for all of State Line
- ●Frost dates read at State Line's scale: Apr 11 to Oct 24
YOUR Parcel
- ✓Your exact zone, not State Line's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in State Line
Pull a site-specific report for your exact address in State Line, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that State Line averages can't show:
We read public map data around State Line — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the State Line average
How we know this about State Line
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 State Line’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 State Line
When does frost risk typically end in State Line?
The last hard freeze (28°F) in State Line typically lands around Apr 11, 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 2.
When is the first frost in State Line?
The first hard freeze (28°F) in State Line typically arrives around Oct 24, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 10, so the watching starts about Sep 24 — about 196 days after the spring freeze cleared.
How long is the growing season in State Line?
Measured between 28°F hard freezes, State Line sees about 196 frost-free days — roughly Apr 11 through Oct 24, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 2 to Oct 10, about 161 days.
Is the soil safe to grow vegetables in State Line?
The federal record around State Line runs heavier than most — 517 documented sites, mostly Underground Storage Tanks entries (191), the nearest Underground Storage Tanks record about 0.1 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 I protect my plants from frost in State Line?
From about Sep 24 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 24 (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 24. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at State Line's scale — its 7a band and its 196-day season. Your yard writes its own version of State Line'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 State Line’s own scale
6 of the readings below were taken at State Line's own scale — its own ~196-day season between 28°F freezes, the 70 acres it covers and 517 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- State Line's own USDA hardiness band, zones 7aUSDA PHZM 2023
- State Line's own 28°F hard-freeze dates, about Apr 11 and Oct 24 and the ~196-day span between themNOAA 1991–2020 Climate Normals
- 517 documented contamination sites on the federal record near State Line, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- State Line's boundary and the 70 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~196-day seasonGrowable Ground crop-matching engine
- The ecoregion at State Line's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so State Line's 70 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 State Line's 70 acreswhy one lot differs from the next →
- Which side of State Line you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 70 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 State Line-wide figureread your own land →
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