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

Planting zone for Boise, ID

Boise, ID is in USDA zones 6b to 7a across its 26 ZIP codes. The median last spring frost is April 24 and the first fall frost October 21.

Boise on the zone map

Outlined: its 10 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.

Zones6b–7a−5 to 5 °F
ZIP codes26
Last frostApr 24
First frostOct 21
Growing season179 days

6b 1 ZIP   7a 25 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Boise, ID…

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 Boise, ID

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 24median — 50% chance of a later frost
Safe for tender plantsMay 9only 10% chance of frost after
First fall frostOctober 21median — 10% chance by Oct 5
Growing season179 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 2 and returns around October 31.

From the NOAA station Boise Air Terminal, ID, elevation 2,815 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 Boise

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 13 – Mar 27
SpinachSow outdoors · Mar 13 – Apr 3
Broccoli, cabbageStart indoors · Feb 13 – Feb 27
Broccoli, cabbageTransplant · Apr 3 – Apr 17
Onion setsPlant outdoors · Mar 27 – Apr 10
PotatoesPlant outdoors · Apr 3 – Apr 17
LettuceSow outdoors · Mar 27 – Apr 10
Carrots, beetsSow outdoors · Apr 3 – Apr 17
TomatoesStart indoors · Feb 27 – Mar 13
TomatoesTransplant · May 1 – May 15
Peppers, eggplantStart indoors · Feb 13 – Feb 27
Peppers, eggplantTransplant · May 8 – May 22
BeansSow outdoors · May 1 – May 15
Sweet cornSow outdoors · May 1 – May 15
Cucumbers, squashSow outdoors · May 1 – May 15
Fall lettuce, spinachSow outdoors · Aug 26 – Sep 9
GarlicPlant cloves · Oct 7 – Nov 11
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 24) and first fall frost (Oct 21) 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 83705 came on Mar 4 — 17 days earlier than the 1991–2020 average (Mar 21).

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 6b in Idaho

570 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 98

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 276

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 154

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 Boise, ID.

Soil in Boise, ID

The soil mapped at the center of ZIP 83705 is Elijah — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Elijah silt loam, 2 to 4 percent slopes.

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 83705; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Boise, ID

Summer high93 °Faverage high, July
Winter low25 °Faverage low, December
Hot days55days a year at 90 °F or more
Freezing nights108nights a year at 32 °F or less
Growing degree days3,290base 50 °F — the season’s usable heat
Longest day15 h 26 mindaylight on June 21
Shortest day8 h 56 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation11.5 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 39 °F, low 26 °F 39°26° JanFebruary: average high 46 °F, low 29 °F 46°29° FebMarch: average high 56 °F, low 35 °F 56°35° MarApril: average high 62 °F, low 40 °F 62°40° AprMay: average high 72 °F, low 48 °F 72°48° MayJune: average high 81 °F, low 54 °F 81°54° JunJuly: average high 93 °F, low 62 °F 93°62° JulAugust: average high 91 °F, low 61 °F 91°61° AugSeptember: average high 80 °F, low 53 °F 80°53° SepOctober: average high 65 °F, low 42 °F 65°42° OctNovember: average high 49 °F, low 32 °F 49°32° NovDecember: average high 39 °F, low 25 °F 39°25° Dec

Precipitation by month inches

0″1″2″January: 1.41 in precipitation 1.4 JanFebruary: 1.00 in precipitation 1.0 FebMarch: 1.33 in precipitation 1.3 MarApril: 1.25 in precipitation 1.3 AprMay: 1.45 in precipitation 1.4 MayJune: 0.75 in precipitation 0.8 JunJuly: 0.21 in precipitation 0.2 JulAugust: 0.17 in precipitation 0.2 AugSeptember: 0.43 in precipitation 0.4 SepOctober: 0.81 in precipitation 0.8 OctNovember: 1.18 in precipitation 1.2 NovDecember: 1.53 in precipitation 1.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Boise Air Terminal, ID (within 1 mile); precipitation: Boise NWS WFO, ID (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Boise

837017a
0 to 5 °F
837027a
0 to 5 °F
837037a
0 to 5 °F
837047a
0 to 5 °F
837057a
0 to 5 °F
837067a
0 to 5 °F
837077a
0 to 5 °F
837087a
0 to 5 °F
837097a
0 to 5 °F
837117a
0 to 5 °F
837127a
0 to 5 °F
837137a
0 to 5 °F
837157a
0 to 5 °F
837166b
−5 to 0 °F
837177a
0 to 5 °F
837197a
0 to 5 °F
837207a
0 to 5 °F
837227a
0 to 5 °F
837247a
0 to 5 °F
837267a
0 to 5 °F
837287a
0 to 5 °F
837297a
0 to 5 °F
837327a
0 to 5 °F
837357a
0 to 5 °F
837567a
0 to 5 °F
837997a
0 to 5 °F

Idaho planting zones →

Questions about Boise

What planting zone is Boise, ID?

Boise, ID is in USDA hardiness zones 6b to 7a on the 2023 map (6b: −5 to 0 °F; 7a: 0 to 5 °F).

When is the last frost in Boise, ID?

The median last spring frost is April 24 and the median first fall frost is October 21 (NOAA 1991–2020 normals, Boise Air Terminal station).

When can I plant a garden in Boise, ID?

Cool-season crops like peas and spinach go in around Mar 13 – Apr 3; tomatoes, peppers, beans and squash after about May 1, once frost risk has passed.

What kind of onions grow in Boise, ID?

Long-day onions: the longest day is 15 h 26 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Boise, ID get?

About 11.5 inches of precipitation a year (NOAA 1991–2020 normals).