The Treasure Valley spans USDA hardiness zones 6a-7a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Idaho's Boise-anchored growing corridor: the warm valley floor around Ada and Canyon counties reaches roughly 200 frost-free days at USDA zone 7a, while the Boise and Owyhee foothills that ring it run up to a full zone colder on a markedly shorter season. The conditions favor potato, lentil, apple, and hop, among others — though every individual site edits that list with its own soil, sun, and drainage.
The Treasure Valley spans Idaho.
Your yard isn't all of the Treasure Valley.
The Treasure Valley spans USDA zones 6a-7a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Treasure Valley — soil, climate, flood, and parcel records. How we handle your address.
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The Treasure Valley — the short answer
The Treasure Valley: USDA zones 6a-7a, 125–205 frost-free days depending where in it you stand, in Idaho.
- USDA zones
- 6a-7a
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 125 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Boise County
- Counties
- 5
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 5 member counties, not a state or national average.
Hardiness Zone Range
The Treasure Valley is not one growing season
One answer for the Treasure Valley averages 5 counties whose growing seasons are 80 days apart — from 125 frost-free days in Boise County to 205 in Canyon County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 5 counties runs 137–205 days, with a median of 174 days — a 80-day span end to end.
Measured across 5 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
What Grows in the Treasure Valley
All 1 of the plants below that publish a season requirement clear even Boise County’s 125 frost-free days — so on season alone, this grid works at both ends of the region. The 80-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the Treasure Valley's USDA zones 6a-7a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Treasure Valley
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Treasure Valley’s USDA zones 6a-7a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Treasure Valley
The USDA soil survey maps this ground county by county. These are those records weighted by land area across five member counties — this region’s own profile, not a state figure.
The ground is predominantly Aridisols, at 43% of mapped acres, followed by Mollisols (36%), Alfisols (9%) and Entisols (9%). Eight soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Purdam, Wickahoney, and Arbidge.
80% of those acres are well drained, and another 10% somewhat excessively drained, 3% excessively drained. Topsoil pH runs 5.9–7.9 between the lowest and the highest county on record.
Soil order
Aridisols
Drainage
Well drained
Topsoil pH
5.9–7.9
Hydric soils
1%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Owyhee County holds the most wetland ground here, at 1% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Treasure Valley
The soil survey reads this ground county by county, and the readings above are those records summed across the Treasure Valley. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records80% of the mapped acres across the Treasure Valley are well drained — ground that drains quickly. That is area-weighted across all five of its mapped counties.
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
From county recordsTopsoil across the Treasure Valley runs pH 5.9–7.9 — near neutral in four of its five counties.
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
Safe to Grow Here?
What the federal record shows across the Treasure Valley — and how to grow with it.
Across the Treasure Valley's 5 counties the federal record holds 5,387 documented sites, mostly Nitrate (3,106), Underground Storage Tanks (1,265) and Brownfields (481). The heaviest single county is Ada County, with 2,791.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Treasure Valley to see which records sit where you actually grow.
Sources Checked
Summed across the 5 counties in the Treasure Valley
A note from Gnorman
What an experienced grower watches for around here
In and around the Treasure Valley, two things run higher than the national average across the 5 counties in the Treasure Valley — Nitrate (3,106 sites) and CAFO (55 sites). That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Treasure Valley
Everything above resolves to the Treasure Valley as a whole — a footprint whose own counties record seasons 80 days apart, and hardiness across zones 6a-7a. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Treasure Valley Average
Treasure Valley Average
- ●USDA Zones 6a-7a, averaged across Treasure Valley
- ●One soil character for all of Treasure Valley
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Treasure Valley's 6a-7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Treasure Valley
Pull a site-specific report for your exact address in the Treasure Valley — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Treasure Valley averages can't show:
We read public map data around The Treasure Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Treasure Valley average
How we know this about the Treasure Valley
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Treasure Valley
What hardiness zone is the Treasure Valley?
The Treasure Valley spans USDA hardiness zones 6a-7a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Treasure Valley?
Measured between 28°F hard freezes, the Treasure Valley's counties mostly run 137 to 205 frost-free days, median 174 (NOAA Regional Climate Centers ACIS, 1991–2020, over 5 member counties). That 68-day spread is the honest read — no single season describes 5 counties, and each county guide below carries its own.
When does frost risk end in the Treasure Valley?
Across the Treasure Valley, the middle half of member counties see their last 28°F hard freeze between Apr 9 and May 20 (median Apr 30), and their first fall freeze between Oct 4 and Oct 27. Those are hard freezes, not the last light frost: tender transplants wait for about May 21, and elevation decides which end of a 41-day spread you garden in.
What grows well in the Treasure Valley?
The Treasure Valley's conditions suit plants such as Potato, Lentil, Apple, Hop, Cherry. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Treasure Valley defined?
The Treasure Valley is defined here as a curated cluster of 5 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Treasure Valley cover?
The Treasure Valley spans Idaho. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Columbia Basin, Snake River Plain, Eastern Idaho (Upper Snake River Valley), Magic Valley, Idaho Panhandle (North Idaho), and Central Idaho Mountains share at least one state with the Treasure Valley. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Treasure Valley’s own scale
6 of the readings below were taken at the Treasure Valley's own scale — the zone 6a-7a band across its footprint, a median 174-day season across its 5 counties and 5,387 documented federal contamination records across its 5 counties, 2,791 of them in Ada County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 6a-7a aggregated across all 5 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 5 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 5 counties run 137 to 205 frost-free days, median 174NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 5,387 documented federal contamination records across its 5 counties, 2,791 of them in Ada County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 43% Aridisols, topsoil pH 5.9–7.9, area-weighted across its 5 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 6a-7afrom Idaho
What this page can’t tell you
- Which end of the 68-day range your ground sits at — 137 days at one extreme, 205 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Treasure Valley
State growing guides
Counties in this region
Other growing regions across Idaho
A dry basalt plateau of loess soils in the inland Northwest where irrigation turns arid ground into apple, cherry, hop, and wine-grape country.
A broad volcanic plain of deep ash-rich soils and long summer days, irrigated from the Snake River — the classic Idaho potato, hop, and sugar-beet country.
Eastern Idaho's Upper Snake River Valley is the cold, high-elevation head of the same volcanic plain that gives Boise its 7a warmth — but here the growing reality inverts. At roughly 4,500–6,000 ft, Idaho Falls, Pocatello, and Rexburg sit in USDA zones 5a–5b with about 130–165 frost-free days at the population centers (shorter still in the outlying mountain valleys like Bear Lake and Caribou), running 1.5–2 zones colder and 40–70 days shorter than the Treasure Valley downstream. Routine late-May frosts make this short-season, cold-hardy, high-desert growing — the mirror image of the plain's warm western end that the broad Snake River Plain page averages away.
The irrigated heart of south-central Idaho, where Snake River canal water — the "magic" that turned high desert into cropland after the 1905 Milner Dam and the Carey Act land tracts — feeds a tight 6a–6b band on volcanic-ash soils at roughly 3,700 feet. Cooler and far more uniform than the wider Snake River Plain that runs from balmy Boise (7a) to the frosty eastern plain (5b), this is Idaho's dairy, sugar-beet, dry-edible-bean, and malting-barley heartland, with the Snake River Canyon and Shoshone Falls cutting straight through it.
Forested, lake-and-mountain far-north Idaho — nothing like the arid Snake River Plain or the treeless Palouse wheat prairie to the south. Big glacial lakes (Pend Oreille, Coeur d'Alene) buffer both spring frost and summer heat across a humid-continental, higher-precipitation belt of cedar-and-hemlock forest soils. Expect USDA zones 6a–6b and a cool, wet-spring season of roughly 148–187 frost-free days (verified county climate data), with last frosts into mid-May in the northern valleys — a short, moist window the southern-Idaho and Palouse pages can't describe.
Idaho's shortest growing season: the central Rockies high country runs just 94 frost-free days at Valley County (McCall), 104 at Custer (Stanley/Challis), and 110–117 across Idaho and Lemhi (Salmon) — a full 30–50 days shorter than the Wood River Valley one range south (Blaine, 143 days), with cold-air pooling that can drop frost into any summer month. At 4,000–6,500 ft in USDA 5a–6a, growers here lean on season extension, short-season and short-day varieties, and careful frost-pocket siting rather than fighting the calendar.