Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for Idaho Falls, ID

Idaho Falls, ID is in USDA zone 5b across its 7 ZIP codes. The median last spring frost is May 9 and the first fall frost October 1.

Idaho Falls on the zone map

Outlined: its 4 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone5b−15 to −10 °F
ZIP codes7
Last frostMay 9
First frostOct 1
Growing season142 days

5b 7 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Idaho Falls, ID

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 9median — 50% chance of a later frost
Safe for tender plantsJune 2only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 17
Growing season142 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 28 and returns around October 13.

From the NOAA station Idaho Falls - Kifi, ID, elevation 4,741 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Idaho Falls

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 28 – Apr 11
SpinachSow outdoors · Mar 28 – Apr 18
Broccoli, cabbageStart indoors · Feb 28 – Mar 14
Broccoli, cabbageTransplant · Apr 18 – May 2
Onion setsPlant outdoors · Apr 11 – Apr 25
PotatoesPlant outdoors · Apr 18 – May 2
LettuceSow outdoors · Apr 11 – Apr 25
Carrots, beetsSow outdoors · Apr 18 – May 2
TomatoesStart indoors · Mar 14 – Mar 28
TomatoesTransplant · May 16 – May 30
Peppers, eggplantStart indoors · Feb 28 – Mar 14
Peppers, eggplantTransplant · May 23 – Jun 6
BeansSow outdoors · May 16 – May 30
Sweet cornSow outdoors · May 16 – May 30
Cucumbers, squashSow outdoors · May 16 – May 30
Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20
GarlicPlant cloves · Sep 17 – Oct 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 9) and first fall frost (Oct 1) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 83403 came on Mar 21 — 24 days earlier than the 1991–2020 average (Apr 14).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 5b in Idaho

553 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 30

balsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FDouglas-fir200 ft · blooms mid spring · medium shade tolerance · to −33 °FEngelmann spruce120 ft · blooms late spring · low shade tolerance · to −50 °F

Shrubs 94

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FBarclay's willow15 ft · high shade tolerance · to −43 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °F

Wildflowers & perennials 267

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °F

Grasses 151

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 1

western white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Idaho Falls, ID.

Soil in Idaho Falls, ID

The soil mapped at the center of ZIP 83403 is Bannock — loam, well drained.

TextureLoama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Bannock loam.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 83403; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Idaho Falls, ID

Summer high86 °Faverage high, July
Winter low16 °Faverage low, January
Hot days28days a year at 90 °F or more
Freezing nights166nights a year at 32 °F or less
Growing degree days2,241base 50 °F — the season’s usable heat
Longest day15 h 25 mindaylight on June 21
Shortest day8 h 57 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation13.5 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 30 °F, low 16 °F 30°16° JanFebruary: average high 36 °F, low 20 °F 36°20° FebMarch: average high 48 °F, low 29 °F 48°29° MarApril: average high 58 °F, low 34 °F 58°34° AprMay: average high 67 °F, low 42 °F 67°42° MayJune: average high 77 °F, low 49 °F 77°49° JunJuly: average high 86 °F, low 55 °F 86°55° JulAugust: average high 86 °F, low 54 °F 86°54° AugSeptember: average high 75 °F, low 45 °F 75°45° SepOctober: average high 59 °F, low 35 °F 59°35° OctNovember: average high 43 °F, low 25 °F 43°25° NovDecember: average high 31 °F, low 17 °F 31°17° Dec

Precipitation by month inches

0″1″2″January: 1.06 in precipitation 1.1 JanFebruary: 0.95 in precipitation 0.9 FebMarch: 1.26 in precipitation 1.3 MarApril: 1.43 in precipitation 1.4 AprMay: 1.93 in precipitation 1.9 MayJune: 1.25 in precipitation 1.3 JunJuly: 0.51 in precipitation 0.5 JulAugust: 0.65 in precipitation 0.7 AugSeptember: 1.13 in precipitation 1.1 SepOctober: 1.23 in precipitation 1.2 OctNovember: 0.95 in precipitation 0.9 NovDecember: 1.14 in precipitation 1.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Idaho Falls - Kifi, ID (4 mi away); precipitation: Idaho Falls - Kifi, ID (4 mi away). Daylight is calculated from latitude.

ZIP codes in Idaho Falls

834015b
−15 to −10 °F
834025b
−15 to −10 °F
834035b
−15 to −10 °F
834045b
−15 to −10 °F
834055b
−15 to −10 °F
834065b
−15 to −10 °F
834155b
−15 to −10 °F

Idaho planting zones →

Questions about Idaho Falls

What planting zone is Idaho Falls, ID?

Idaho Falls, ID is in USDA hardiness zone 5b on the 2023 map (5b: −15 to −10 °F).

When is the last frost in Idaho Falls, ID?

The median last spring frost is May 9 and the median first fall frost is October 1 (NOAA 1991–2020 normals, Idaho Falls - Kifi station).

When can I plant a garden in Idaho Falls, ID?

Cool-season crops like peas and spinach go in around Mar 28 – Apr 18; tomatoes, peppers, beans and squash after about May 16, once frost risk has passed.

What kind of onions grow in Idaho Falls, ID?

Long-day onions: the longest day is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Idaho Falls, ID get?

About 13.5 inches of precipitation a year (NOAA 1991–2020 normals).