Ketchum, Idaho, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Growers here do well with okra, blackberry, lavender, and pumpkin — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Ketchum, 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 Ketchum 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 Ketchum — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Ketchum — the short answer
Ketchum, Idaho: USDA zone 5b, about 110 days between hard freezes, across 2K acres of city.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jun 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~110
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 2K 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 5b is Ketchum's average, not your lot's — a low corner or a tree line moves it. Against Ketchum's 110-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Ketchum
Each reading below is measured for Ketchum itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredKetchum runs about 110 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredKetchum sits in USDA hardiness zone 5b.
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 Ketchum is in
Ketchum sits in the Idaho Batholith — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Ketchum's own centroid rather than borrowed from Blaine County.
What Grows in Ketchum
Every plant below cleared Ketchum's own zone 5b and its 110-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Ketchum?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around May 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jun 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 23 — long-season crops need about 90 days of runway, quick greens only 30. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
What's on the federal record near Ketchum
Closest first, within ~10 miles of Ketchum. Listing isn't leaking, and distance isn't exposure.
- 04N 17E 13ABA1Nitrate · 25 ft
- SUN VALLEY CARWASHUnderground Storage Tanks · 700 ft
- Loomis Inc.Underground Storage Tanks · 750 ft
- LUTZ RENTALUnderground Storage Tanks · 850 ft
- 04N 17E 13AAB1Nitrate · 850 ft
- IDAHO BIOSCIENCEBrownfields · 950 ft
- CLEARWATER LANDSCAPINGUnderground Storage Tanks · 1100 ft
- KETCHUM AUTOMOTIVEUnderground Storage Tanks · 1300 ft
- KETCHUM CITY WARM SPRINGS BOOSTER STATIONUnderground Storage Tanks · 1300 ft
- Base Camp Warm SpringsUnderground Storage Tanks · 1300 ft
- 04N 17E 12CDD1Nitrate · 1400 ft
- JACKSONS FOOD STORE #106Underground Storage Tanks · 1500 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Ketchum'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 Ketchum.
Total Sites
251
within ~10 miles of Ketchum
Risk Level
High
Highest-severity
7 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Ketchum
Severity Distribution
within ~10 miles of Ketchum
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Ketchum, two things run higher than the national average within ~10 miles of Ketchum — Mining (126 sites) and Superfund (7 sites). That's not a problem with your land — it's information about 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 Ketchum
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 Ketchum average
Your land is one point inside Ketchum
Everything above resolves to Ketchum as a whole — one PHZM band and one 28°F frost record, read across 2K 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 Ketchum Average
Ketchum Average
- ●USDA Zones 5b, averaged across Ketchum
- ●One soil character for all of Ketchum
- ●Frost dates read at Ketchum's scale: Jun 5 to Sep 23
YOUR Parcel
- ✓Your exact zone, not Ketchum's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Ketchum
Pull a site-specific report for your exact address in Ketchum, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Ketchum averages can't show:
We read public map data around Ketchum — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ketchum average
How we know this about Ketchum
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 Ketchum’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 Ketchum
When does frost risk typically end in Ketchum?
The last hard freeze (28°F) in Ketchum typically lands around Jun 5, 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 Jun 26.
When is the first frost in Ketchum?
The first hard freeze (28°F) in Ketchum typically arrives around Sep 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 9, so the watching starts about Aug 24 — about 110 days after the spring freeze cleared.
How long is the growing season in Ketchum?
Measured between 28°F hard freezes, Ketchum sees about 110 frost-free days — roughly Jun 5 through Sep 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 26 to Sep 9, about 75 days.
Is the soil safe to grow vegetables in Ketchum?
The federal record around Ketchum runs heavier than most — 251 documented sites, mostly Mining entries (126), the nearest Nitrate record under a tenth of a mile 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 gardeners stretch the season in Ketchum?
With about 110 frost-free days between hard freezes, Ketchum rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 138 to 166 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the Jun 5 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Ketchum's scale — its 5b band and its 110-day season. Your yard writes its own version of Ketchum'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 Ketchum’s own scale
6 of the readings below were taken at Ketchum's own scale — its own ~110-day season between 28°F freezes, the 2,052 acres it covers and 251 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Ketchum's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Ketchum's own 28°F hard-freeze dates, about Jun 5 and Sep 23 and the ~110-day span between themNOAA 1991–2020 Climate Normals
- 251 documented contamination sites on the federal record near Ketchum, the closest Nitrate record under a tenth of a mile out from the town centreFederal environmental registers
- Ketchum's boundary and the 2,052 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~110-day seasonGrowable Ground crop-matching engine
- The ecoregion at Ketchum's own centroid, the Idaho BatholithUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Ketchum's 2,052 acres read through its county's SSURGO summaryfrom Blaine County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Blaine 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 Blaine County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Ketchum's 2,052 acreswhy one lot differs from the next →
- Which side of Ketchum you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,052 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 Ketchum-wide figureread your own land →