Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 30, 2026

Planting zone for 83858 — Rathdrum, ID

ZIP code 83858 (Rathdrum, Kootenai County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 22 and the first fall frost October 18.

Where ZIP 83858 is

Outlined: the ZIP code area · 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 frostApr 22

First frostOct 18

2012 zone6b

Same zone as on the 2012 map. 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 Rathdrum, 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 Rathdrum, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 22median — 50% chance of a later frost

Safe for tender plantsMay 6only 10% chance of frost after

First fall frostOctober 18median — 10% chance by Oct 4

Growing season179 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 1.

From the NOAA station Coeur D'Alene, ID — 13 miles away, elevation 2,133 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 83858

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 11 – Mar 25

SpinachSow outdoors · Mar 11 – Apr 1

Broccoli, cabbageStart indoors · Feb 11 – Feb 25

Broccoli, cabbageTransplant · Apr 1 – Apr 15

Onion setsPlant outdoors · Mar 25 – Apr 8

PotatoesPlant outdoors · Apr 1 – Apr 15

LettuceSow outdoors · Mar 25 – Apr 8

Carrots, beetsSow outdoors · Apr 1 – Apr 15

TomatoesStart indoors · Feb 25 – Mar 11

TomatoesTransplant · Apr 29 – May 13

Peppers, eggplantStart indoors · Feb 11 – Feb 25

Peppers, eggplantTransplant · May 6 – May 20

BeansSow outdoors · Apr 29 – May 13

Sweet cornSow outdoors · Apr 29 – May 13

Cucumbers, squashSow outdoors · Apr 29 – May 13

Fall lettuce, spinachSow outdoors · Aug 23 – Sep 6

GarlicPlant cloves · Oct 4 – Nov 8

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 22) and first fall frost (Oct 18) 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 83858 came on Apr 11 — 3 days earlier than the 1991–2020 average (Apr 14).

average
Apr 142026
Apr 11

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 Rathdrum, ID.

Soil in Rathdrum, ID

The soil mapped at the center of ZIP 83858 is Vassar — 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: Vassar ashy silt loam, 5 to 30 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 83858; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rathdrum, ID

Summer high83 °Faverage high, July

Winter low26 °Faverage low, January

Hot days18days a year at 90 °F or more

Freezing nights120nights a year at 32 °F or less

Growing degree days2,202base 50 °F — the season’s usable heat

Longest day16 h 01 mindaylight on June 21

Shortest day8 h 23 mindaylight on December 21

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

Precipitation45.2 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: Coeur D'Alene, ID (13 mi away); precipitation: Ragged Mountain, ID (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

838696b

Spirit Lake, ID · 9 mi

990256b

Newman Lake, WA · 9 mi

838546b

Post Falls, ID · 10 mi

838776b

Post Falls, ID · 10 mi

838156b

Coeur d'Alene, ID · 10 mi

Blanchard, ID · 13 mi

Idaho planting zones →

Questions about 83858

What planting zone is ZIP code 83858?

ZIP code 83858 (Rathdrum, 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 Rathdrum, ID?

The median last spring frost (32 °F) near 83858 is April 22; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Coeur D'Alene station.

When is the first frost in Rathdrum, ID?

The median first fall frost near 83858 is October 18, giving a median frost-free growing season of 179 days.

When should I plant tomatoes in 83858?

Start tomato seeds indoors around Feb 25 – Mar 11 and set transplants outside around Apr 29 – May 13, one to three weeks after the median last frost.

How much rain and snow does 83858 get?

About 45.2 inches of precipitation a year (NOAA 1991–2020 normals, Ragged Mountain station).

How hot do summers get in Rathdrum, ID?

The average high peaks at 83 °F in July, with about 18 days a year at 90 °F or more.

What kind of soil does 83858 have?

The USDA soil survey maps Vassar at the center of ZIP 83858: slightly decomposed plant material, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Rathdrum, ID in 2026?

Spring leaf-out near 83858 came on Apr 11 in 2026, 3 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Rathdrum, ID?

Long-day onions: the longest day near 83858 is 16 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).