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

Planting zone for 59724 — Dell, MT

ZIP code 59724 (Dell, Beaverhead County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is June 11 and the first fall frost September 10.

Where ZIP 59724 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.

Zone5a−20 to −15 °F

Coldest night−28.9 to −26.1 °C

Last frostJun 11

First frostSep 10

2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Dell, 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 Dell, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 11median — 50% chance of a later frost

Safe for tender plantsJune 30only 10% chance of frost after

First fall frostSeptember 10median — 10% chance by Aug 27

Growing season89 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 21 and returns around September 23.

From the NOAA station Lima, MT — 11 miles away, elevation 6,280 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 59724

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 30 – May 14

SpinachSow outdoors · Apr 30 – May 21

Broccoli, cabbageStart indoors · Apr 2 – Apr 16

Broccoli, cabbageTransplant · May 21 – Jun 4

Onion setsPlant outdoors · May 14 – May 28

PotatoesPlant outdoors · May 21 – Jun 4

LettuceSow outdoors · May 14 – May 28

Carrots, beetsSow outdoors · May 21 – Jun 4

TomatoesStart indoors · Apr 16 – Apr 30

TomatoesTransplant · Jun 18 – Jul 2

Peppers, eggplantStart indoors · Apr 2 – Apr 16

Peppers, eggplantTransplant · Jun 25 – Jul 9

BeansSow outdoors · Jun 18 – Jul 2

Sweet cornSow outdoors · Jun 18 – Jul 2

Cucumbers, squashSow outdoors · Jun 18 – Jul 2

Fall lettuce, spinachSow outdoors · Jul 16 – Jul 30

GarlicPlant cloves · Aug 27 – Oct 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 11) and first fall frost (Sep 10) 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 59724 came on Apr 23 — 17 days earlier than the 1991–2020 average (May 10).

average
May 102026
Apr 23

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 5a in Montana

548 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. 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 Dell, MT.

Soil in Dell, MT

The soil mapped at the center of ZIP 59724 is Nikat — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter5%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Nikat gravelly loam, 15 to 50 percent slopes, very 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 59724; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dell, MT

Summer high83 °Faverage high, July

Winter low11 °Faverage low, January

Hot days5days a year at 90 °F or more

Freezing nights226nights a year at 32 °F or less

Growing degree days1,426base 50 °F — the season’s usable heat

Longest day15 h 34 mindaylight on June 21

Shortest day8 h 48 mindaylight on December 21

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

Precipitation10.3 inper year, rain and melted snow

Snowfall53 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Lima, MT (11 mi away); precipitation: Lima, MT (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Montana planting zones →

Questions about 59724

What planting zone is ZIP code 59724?

ZIP code 59724 (Dell, MT) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Dell, MT?

The median last spring frost (32 °F) near 59724 is June 11; after June 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Lima station.

When is the first frost in Dell, MT?

The median first fall frost near 59724 is September 10, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 59724?

Start tomato seeds indoors around Apr 16 – Apr 30 and set transplants outside around Jun 18 – Jul 2, one to three weeks after the median last frost.

How much rain and snow does 59724 get?

About 10.3 inches of precipitation a year and 53 inches of snowfall (NOAA 1991–2020 normals, Lima station).

How hot do summers get in Dell, MT?

The average high peaks at 83 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 59724 have?

The USDA soil survey maps Nikat at the center of ZIP 59724: gravelly loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Dell, MT in 2026?

Spring leaf-out near 59724 came on Apr 23 in 2026, 17 days earlier than the 1991–2020 average (May 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dell, MT?

Long-day onions: the longest day near 59724 is 15 h 34 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59724 change?

Yes. The 2012 USDA map put 59724 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.