Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 83865 — Colburn, ID

ZIP code 83865 (Colburn, Bonner County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 8 and the first fall frost September 28.

Where ZIP 83865 is

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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostMay 8

First frostSep 28

2012 zone6a

Was 6a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Colburn, 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 Colburn, ID

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 8median — 50% chance of a later frost

Safe for tender plantsMay 25only 10% chance of frost after

First fall frostSeptember 28median — 10% chance by Sep 11

Growing season141 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 21 and returns around October 10.

From the NOAA station Sandpoint Exp Stn, ID — 6 miles away, elevation 2,126 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 83865

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 27 – Apr 10

SpinachSow outdoors · Mar 27 – Apr 17

Broccoli, cabbageStart indoors · Feb 27 – Mar 13

Broccoli, cabbageTransplant · Apr 17 – May 1

Onion setsPlant outdoors · Apr 10 – Apr 24

PotatoesPlant outdoors · Apr 17 – May 1

LettuceSow outdoors · Apr 10 – Apr 24

Carrots, beetsSow outdoors · Apr 17 – May 1

TomatoesStart indoors · Mar 13 – Mar 27

TomatoesTransplant · May 15 – May 29

Peppers, eggplantStart indoors · Feb 27 – Mar 13

Peppers, eggplantTransplant · May 22 – Jun 5

BeansSow outdoors · May 15 – May 29

Sweet cornSow outdoors · May 15 – May 29

Cucumbers, squashSow outdoors · May 15 – May 29

Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17

GarlicPlant cloves · Sep 14 – Oct 19

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 8) and first fall frost (Sep 28) 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 83865 came on Apr 30 — 8 days earlier than the 1991–2020 average (May 8).

average
May 82026
Apr 30

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.

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 Colburn, ID.

Soil in Colburn, ID

The soil mapped at the center of ZIP 83865 is Jeru — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer

pH5.0strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter75%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Jeru gravelly loam, 35 to 65 percent slopes, extremely stony.

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 83865; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Colburn, ID

Summer high82 °Faverage high, July

Winter low23 °Faverage low, January

Hot days14days a year at 90 °F or more

Freezing nights156nights a year at 32 °F or less

Growing degree days1,745base 50 °F — the season’s usable heat

Longest day16 h 06 mindaylight on June 21

Shortest day8 h 19 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation54.6 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Sandpoint Exp Stn, ID (6 mi away); precipitation: Schweitzer Basin, ID (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

Priest River, ID · 13 mi

Idaho planting zones →

Questions about 83865

What planting zone is ZIP code 83865?

ZIP code 83865 (Colburn, ID) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Colburn, ID?

The median last spring frost (32 °F) near 83865 is May 8; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sandpoint Exp Stn station.

When is the first frost in Colburn, ID?

The median first fall frost near 83865 is September 28, giving a median frost-free growing season of 141 days.

When should I plant tomatoes in 83865?

Start tomato seeds indoors around Mar 13 – Mar 27 and set transplants outside around May 15 – May 29, one to three weeks after the median last frost.

How much rain and snow does 83865 get?

About 54.6 inches of precipitation a year (NOAA 1991–2020 normals, Schweitzer Basin station).

How hot do summers get in Colburn, ID?

The average high peaks at 82 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 83865 have?

The USDA soil survey maps Jeru at the center of ZIP 83865: slightly decomposed plant material, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Colburn, ID in 2026?

Spring leaf-out near 83865 came on Apr 30 in 2026, 8 days earlier than the 1991–2020 average (May 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Colburn, ID?

Long-day onions: the longest day near 83865 is 16 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 83865 change?

Yes. The 2012 USDA map put 83865 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.