Idaho spans USDA hardiness zones 3b-7a, with a growing season of about 150 frost-free days — a season that fits spring and fall plantings of cool-weather crops around a solid warm-season core.
In practice the season is written by 8-35 inches of annual rainfall, a median of roughly 2,700 growing-degree days (base 50°F), and about 1,650 winter chill hours for tree fruit. The ground itself runs to volcanic ash, silt loam, sandy loam, and basalt-derived; drainage character, more than fertility, is usually what sorts the thrivers from the strugglers. Idaho splits into distinct growing country: Columbia Basin, Snake River Plain, and The Palouse, each keeping its own frost calendar. A short list that earns its place here — potato, apple, hop, and cherry — with any one site's soil, sun, and drainage making the final cut.
Grounded inUSDA PHZM 2023•NOAA Climate Normals•USDA NRCS SSURGO•GDD aggregate (Cornell CALS)•Chill-hour aggregate (MSU Extension)•USDA hardiness sub-region map•EPA FRS•USDA PLANTS•Growable Ground suitability scoring
Idaho spans zones 3b-7a, but your yard sits in exactly one — and slope, tree cover, and low spots nudge it further. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Distinct growing regions within Idaho — each has its own zones, soils, and signature crops.
USDA Zones
3b-7a
USDA PHZM 2023
Last Frost
Apr 15 - Jun 15
NOAA 30-yr Normals
First Frost
Sep 1 - Oct 15
NOAA 30-yr Normals
Annual Rainfall
8-35 inches
NOAA Climate Normals
Zone maps are averages across Idaho. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
The soil types that dominate Idaho — how each drains decides more about crop success than almost anything else. Tap any soil to learn what it is and how to work with it.
Drainage
Excellent and unusual: ash soils drain freely yet hold remarkable amounts of plant-available water in their porous structure — the best of both habits.
What thrives
Volcanic regions grow celebrated crops the world over: orchards, berries, vegetables, coffee, and wine grapes all prosper on ash-derived soils.
Drainage
Moderate. Silt holds water well and releases it steadily, though the fine particles can crust after hard rain and compact under traffic.
What thrives
The full vegetable garden does well here, and small grains, corn, and leafy greens are classic silt-loam crops. Its steady moisture suits shallow-rooted plants that dislike drought stress.
Drainage
Fast. The sand fraction opens the soil up, so water moves through the root zone quickly and the surface rarely stays soggy. The trade is that nutrients ride out with the water.
What thrives
Root crops love it — carrots, potatoes, radishes, and onions size up cleanly in ground they can push through. Melons, sweet potatoes, asparagus, and most herbs appreciate the warmth and the drainage.
Drainage
Generally good; basalt soils range from stony and fast-draining on young flows to deeper clay loams on old ones.
What thrives
Wine grapes, orchard fruit, and vegetables all do famously well on basalt-derived soils — volcanic mineral wealth shows up in the harvest.
Soil data: USDA NRCS SSURGO · Soil types explained
Plants well-suited to Idaho's climate, soils, and growing season — each links to its full growing profile.
Rarely: the season closes in stages, not all at once, and each stage has its crops. Across Idaho, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 21, with the middle half of counties between Apr 12 and May 1 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Oct 15 and Oct 30 — 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.
The plants Idaho put its name on — cultural emblems, not growing recommendations.
Syringa (mock orange)
Philadelphus lewisii
Designated 1931.
Western white pine
Pinus monticola
Designated 1935.
Designated 2000. In our plant library — see its full growing profile.
Plants the USDA PLANTS Database documents as native and present in Idaho — a real per-state range, not just a zone match. Presence is statewide, so a plant may still be uncommon in your specific county; your state’s Cooperative Extension or a native-plant society is the local authority.
US-native plants whose hardiness range overlaps Idaho’s USDA zones 3b-7a but which USDA PLANTS doesn’t map to a single state range here. Zone overlap is a starting filter, not a range map.
What an experienced grower plans around here — each one has a move.
Short growing season at higher elevations
At elevation, fast varieties plus a cold frame or low tunnel reliably buy back the weeks the calendar withholds.
Arid conditions require irrigation in most of the state
Drip irrigation and deep mulch are the arid-country baseline — set the water system before the plants.
Cold winter snaps can reach -30F in mountain valleys
Plant perennials for your real zone, not an optimistic one — a -30°F night finds every zone-pushed plant.
For cultivar selection, pest pressure, and planting-time guidance specific to Idaho, the University of Idaho Extension is the authoritative local source.
Safe to Grow Here?What the federal record shows across Idaho — and how to grow with it.
We checked the federal record across Idaho — 21,100 documented sites across 8 of the 9 source types we track.
The most significant on record: 215 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Idaho carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across Idaho
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Idaho, two things run higher than the national average — Mining (3,980 sites) and Nitrate (9,840 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
State averages sketch the shape. Your soil, sun exposure, drainage, and microclimate decide what actually takes. Pull a site-specific report for your exact parcel.
Enter your address. We read your soil, sun, drainage, and frost dates, then score 1,112 plants against the real conditions on your land.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Idaho spans USDA hardiness zones 3b-7a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Rarely: the season closes in stages, not all at once, and each stage has its crops. Across Idaho, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 21, with the middle half of counties between Apr 12 and May 1 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Oct 15 and Oct 30 — 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.
Across Idaho, the middle half of counties see their last hard freeze (28°F) between about Apr 12 and May 1, with a county median near Apr 21 (NOAA 1991–2020 climate normals). That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
Measured between 28°F hard freezes, growing seasons across Idaho's counties mostly run about 169 to 203 days, with a county median near 184 (NOAA 1991–2020 climate normals). Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
Idaho's zones 3b-7a support a wide range — strong performers include Potato, Apple, Hop, Cherry, and Lentil. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Officially, Idaho spans USDA zones 3b-7a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
The federal record across Idaho runs heavier than most — 21,100 documented sites — 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.
Start with three facts. Idaho spans USDA zones 3b-7a, which sets what survives winter; last hard freezes range from about Apr 12 to May 1 across its counties (NOAA 1991–2020 climate normals); and 21,100 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Idaho average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Explore growing conditions by county — each has its own zone range and land area.
Explore growing conditions by city or town in Idaho.
