What Growing Zone Is Idaho In?
USDA hardiness zones
4a to 7b
2023 USDA Plant Hardiness Zone Map
Idaho spans USDA hardiness zone 4a to 7b across its major population centers, according to the 2023 USDA Plant Hardiness Zone Map. That's a real range, not a single number: where you fall in it depends on where in the state you actually are.
Hardiness zone for ZIP 83702 (Boise)
Your USDA hardiness zone
Zone 7a
Avg. annual minimum (°F)
0°F to 5°F
Avg. annual minimum (°C)
-18°C to -15°C
Nearest reference point: Boise, ID
This is a regional estimate based on the nearest of 826 reference points, each matched to the official 2023 USDA zone map. It’s accurate to within about a half-zone across most of the country, but elevation shifts zones over short distances, so if you’re in mountainous terrain, check the official USDA map for your exact address (see Sources below).
Idaho's USDA Hardiness Zones
Here's how the zone shifts across Idaho's major cities:
For your exact zone by ZIP code, use the Hardiness Zone Finder, and for what a zone number actually measures (and doesn't), see how zones actually work.
Frost Dates in Idaho
Frost dates track zone, so they shift across Idaho the same way the zone number does:
- Sawtooth Valley (Stanley) (zone 4): average last frost Apr 23 - May 7, average first frost Sep 23 - Oct 7.
- Boise and Coeur d'Alene (zone 7): average last frost Mar 18 - Apr 1, average first frost Oct 29 - Nov 12.
These are averages, not guarantees. For your specific frost window, use the Frost Date Calculator. For a full vegetable-by-vegetable planting calendar already calculated from Idaho's frost dates, see the Idaho Planting Calendar.
Idaho's zones are dominated by elevation: Stanley, at 6,260 feet in the Sawtooth Valley, averages only about 15 frost-free days a year, while lower-elevation areas around Boise and the Wood River Valley run through zones 2-4 depending on local terrain, per University of Idaho Extension.
What Grows Well in Idaho's Zones
A few real, zone-appropriate picks recommended by University of Idaho Extension for Idaho landscapes: not an exhaustive list, but a genuine starting point.
- Camas lily (Camassia quamash)
- Blanket flower (Gaillardia aristata)
- Columbine (Aquilegia spp.)
- Coral bells (Heuchera spp.)
- Butterfly weed (Asclepias tuberosa)
- Blue false indigo (Baptisia australis)
Ready to find your exact zone? Use the Hardiness Zone Finder: enter your ZIP code for a precise match against the 2023 USDA map.
Idaho Growing Zone FAQ
What growing zone is Idaho in?
Idaho spans USDA hardiness zones 4a to 7b on the 2023 USDA Plant Hardiness Zone Map. Stanley is zone 4a and Idaho Falls is zone 5b; enter your ZIP code in the Hardiness Zone Finder for your exact zone.
What growing zone is Boise, ID?
Boise is in USDA hardiness zone 7a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Stanley, ID?
Stanley is in USDA hardiness zone 4a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Idaho Falls, ID?
Idaho Falls is in USDA hardiness zone 5b on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Coeur d'Alene, ID?
Coeur d'Alene is in USDA hardiness zone 7b on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
Free book · 23 pages, PDF
The Spacing & Planting Cheat Sheet
When to start, when to plant, how far apart.
Sources & further reading
Zone and city data checked against the official USDA Plant Hardiness Zone Map. Plant recommendations sourced from University of Idaho Extension. Climate note sourced from University of Idaho Extension, Bulletin 857. For more on how we build and verify reference data across this site, see our methodology page.
Growing zones in nearby states
Gardening near a state line? Zones don't stop at the border:
- Washington growing zones
- Oregon growing zones
- Utah growing zones
- Nevada growing zones
- Montana growing zones
- Wyoming growing zones
Or browse all 51 state growing-zone guides.