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

Planting zone for 59012 — Birney, MT

ZIP code 59012 (Birney, Rosebud County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 23 and the first fall frost September 15.

Where ZIP 59012 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.

Zone4b−25 to −20 °F

Coldest night−31.7 to −28.9 °C

Last frostMay 23

First frostSep 15

2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Birney, MT…

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 Birney, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 23median — 50% chance of a later frost

Safe for tender plantsJune 7only 10% chance of frost after

First fall frostSeptember 15median — 10% chance by Sep 1

Growing season113 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 11 and returns around September 27.

From the NOAA station Busby, MT — 22 miles away, elevation 3,432 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 59012

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 11 – Apr 25

SpinachSow outdoors · Apr 11 – May 2

Broccoli, cabbageStart indoors · Mar 14 – Mar 28

Broccoli, cabbageTransplant · May 2 – May 16

Onion setsPlant outdoors · Apr 25 – May 9

PotatoesPlant outdoors · May 2 – May 16

LettuceSow outdoors · Apr 25 – May 9

Carrots, beetsSow outdoors · May 2 – May 16

TomatoesStart indoors · Mar 28 – Apr 11

TomatoesTransplant · May 30 – Jun 13

Peppers, eggplantStart indoors · Mar 14 – Mar 28

Peppers, eggplantTransplant · Jun 6 – Jun 20

BeansSow outdoors · May 30 – Jun 13

Sweet cornSow outdoors · May 30 – Jun 13

Cucumbers, squashSow outdoors · May 30 – Jun 13

Fall lettuce, spinachSow outdoors · Jul 21 – Aug 4

GarlicPlant cloves · Sep 1 – Oct 6

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 23) and first fall frost (Sep 15) 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 59012 came on Mar 16 — 22 days earlier than the 1991–2020 average (Apr 7).

average
Apr 72026
Mar 16

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 4b in Montana

506 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. 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 Birney, MT.

Soil in Birney, MT

The soil mapped at the center of ZIP 59012 is Armells — channery loam, well drained.

TextureChannery loama good balance for most vegetables

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Armells-Kirby complex, 25 to 70 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 59012; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Birney, MT

Summer high88 °Faverage high, July

Winter low9 °Faverage low, January

Hot days38days a year at 90 °F or more

Freezing nights193nights a year at 32 °F or less

Growing degree days2,154base 50 °F — the season’s usable heat

Longest day15 h 40 mindaylight on June 21

Shortest day8 h 43 mindaylight on December 21

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

Precipitation15.7 inper year, rain and melted snow

Snowfall52 inper year; 90 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Busby, MT (22 mi away); precipitation: Busby, MT (22 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

590435a

Lame Deer, MT · 16 mi

Ranchester, WY · 37 mi

Montana planting zones →

Questions about 59012

What planting zone is ZIP code 59012?

ZIP code 59012 (Birney, MT) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Birney, MT?

The median last spring frost (32 °F) near 59012 is May 23; after June 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Busby station.

When is the first frost in Birney, MT?

The median first fall frost near 59012 is September 15, giving a median frost-free growing season of 113 days.

When should I plant tomatoes in 59012?

Start tomato seeds indoors around Mar 28 – Apr 11 and set transplants outside around May 30 – Jun 13, one to three weeks after the median last frost.

How much rain and snow does 59012 get?

About 15.7 inches of precipitation a year and 52 inches of snowfall (NOAA 1991–2020 normals, Busby station).

How hot do summers get in Birney, MT?

The average high peaks at 88 °F in July, with about 38 days a year at 90 °F or more.

What kind of soil does 59012 have?

The USDA soil survey maps Armells at the center of ZIP 59012: channery loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Birney, MT in 2026?

Spring leaf-out near 59012 came on Mar 16 in 2026, 22 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Birney, MT?

Long-day onions: the longest day near 59012 is 15 h 40 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59012 change?

Yes. The 2012 USDA map put 59012 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.