Elk River, Idaho, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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.
Even in Elk River, 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 Elk River 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 Elk River — soil, climate, flood, and parcel records. How we handle your address.
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Elk River — the short answer
Elk River, Idaho: USDA zone 6a, about 151 days between hard freezes, across 93 acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~151
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 93 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 Elk River's average, not your lot's — a low corner or a tree line moves it. Against Elk River's 151-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Elk River
Each reading below is measured for Elk River itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredElk River runs about 151 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
MeasuredElk River 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 Elk River is in
Elk River sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Elk River's own centroid rather than borrowed from Clearwater County.
What Grows in Elk River
Every plant below cleared Elk River's own zone 6a and its 151-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Elk River?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 2 — 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.
What's on the federal record near Elk River
Closest first, within ~10 miles of Elk River. Listing isn't leaking, and distance isn't exposure.
- TOM'S TAVERNUnderground Storage Tanks · 400 ft
- ELK RIVER SD #172Underground Storage Tanks · 550 ft
- HUCKLEBERRY HEAVEN LODGEUnderground Storage Tanks · 700 ft
- CLEARWATER HWY DISTUnderground Storage Tanks · 750 ft
- 40N 02E 26BDC1Nitrate · 1300 ft
- USDA FS CLEARWATER NF: ELK RIVER BULKY SITE LANDFILLSuperfund · 2600 ft
- Old Jackson Tunnel ProspectMining · 5.5 mi
- Ruby Creek MineMining · 5.9 mi
- Ruby Creek ProspectMining · 5.9 mi
- Victoria ProspectMining · 6.1 mi
- Gold Hunter ProspectMining · 7.0 mi
Measured from Elk River'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 Elk River.
Total Sites
12
within ~10 miles of Elk River
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Elk River
Severity Distribution
within ~10 miles of Elk River
Highest-Severity Sites
Know Before You Grow
- •Mine waste leaches heavy metals. Test for lead, arsenic and cadmium before growing food here.
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Elk River
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 Elk River average
Your land is one point inside Elk River
Everything above resolves to Elk River as a whole — one PHZM band and one 28°F frost record, read across 93 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 Elk River Average
Elk River Average
- ●USDA Zones 6a, averaged across Elk River
- ●One soil character for all of Elk River
- ●Frost dates read at Elk River's scale: May 4 to Oct 2
YOUR Parcel
- ✓Your exact zone, not Elk River's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Elk River
Pull a site-specific report for your exact address in Elk River, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Elk River averages can't show:
We read public map data around Elk River — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Elk River average
How we know this about Elk River
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 Elk River’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 Elk River
When does frost risk typically end in Elk River?
The last hard freeze (28°F) in Elk River typically lands around May 4, 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 25.
When is the first frost in Elk River?
The first hard freeze (28°F) in Elk River typically arrives around Oct 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 18, so the watching starts about Sep 2 — about 151 days after the spring freeze cleared.
How long is the growing season in Elk River?
Measured between 28°F hard freezes, Elk River sees about 151 frost-free days — roughly May 4 through Oct 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 25 to Sep 18, about 116 days.
Is the soil safe to grow vegetables in Elk River?
The federal record around Elk River is a meaningful one — 12 documented sites, mostly Mining entries (5), the nearest Underground Storage Tanks record under a tenth of a mile 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 Elk River?
From about Sep 2 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 2 (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 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Elk River's scale — its 6a band and its 151-day season. Your yard writes its own version of Elk River'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 Elk River’s own scale
6 of the readings below were taken at Elk River's own scale — its own ~151-day season between 28°F freezes, the 93 acres it covers and 12 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Elk River's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Elk River's own 28°F hard-freeze dates, about May 4 and Oct 2 and the ~151-day span between themNOAA 1991–2020 Climate Normals
- 12 documented contamination sites on the federal record near Elk River, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Elk River's boundary and the 93 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~151-day seasonGrowable Ground crop-matching engine
- The ecoregion at Elk River's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Elk River's 93 acres read through its county's SSURGO summaryfrom Clearwater County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Clearwater 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 Clearwater County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Elk River's 93 acreswhy one lot differs from the next →
- Which side of Elk River you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 93 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Elk River-wide figureread your own land →
More in Idaho
Wider growing context
What grows across IdahoElk River sits outside our named growing regions, so Idaho as a whole is its closest context here.