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

Planting zone for 58655 — South Heart, ND

ZIP code 58655 (South Heart, Stark County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 18 and the first fall frost September 25.

Where ZIP 58655 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 18

First frostSep 25

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 South Heart, ND…

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 South Heart, ND

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 18median — 50% chance of a later frost

Safe for tender plantsMay 31only 10% chance of frost after

First fall frostSeptember 25median — 10% chance by Sep 12

Growing season129 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 3.

From the NOAA station Theodore Roosevelt Airport, ND — 11 miles away, elevation 2,579 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 58655

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 6 – Apr 20

SpinachSow outdoors · Apr 6 – Apr 27

Broccoli, cabbageStart indoors · Mar 9 – Mar 23

Broccoli, cabbageTransplant · Apr 27 – May 11

Onion setsPlant outdoors · Apr 20 – May 4

PotatoesPlant outdoors · Apr 27 – May 11

LettuceSow outdoors · Apr 20 – May 4

Carrots, beetsSow outdoors · Apr 27 – May 11

TomatoesStart indoors · Mar 23 – Apr 6

TomatoesTransplant · May 25 – Jun 8

Peppers, eggplantStart indoors · Mar 9 – Mar 23

Peppers, eggplantTransplant · Jun 1 – Jun 15

BeansSow outdoors · May 25 – Jun 8

Sweet cornSow outdoors · May 25 – Jun 8

Cucumbers, squashSow outdoors · May 25 – Jun 8

Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14

GarlicPlant cloves · Sep 11 – Oct 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 18) and first fall frost (Sep 25) 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 58655 came on Apr 8 — 10 days earlier than the 1991–2020 average (Apr 18).

average
Apr 182026
Apr 8

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 North Dakota

372 plants native to the lower 48 states, recorded in North Dakota, 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 South Heart, ND.

Soil in South Heart, ND

The soil mapped at the center of ZIP 58655 is Daglum — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables

pH6.6neutral; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter3%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Daglum-Rhoades complex, 0 to 6 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 58655; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in South Heart, ND

Summer high84 °Faverage high, July

Winter low6 °Faverage low, January

Hot days20days a year at 90 °F or more

Freezing nights189nights a year at 32 °F or less

Growing degree days2,094base 50 °F — the season’s usable heat

Longest day15 h 52 mindaylight on June 21

Shortest day8 h 32 mindaylight on December 21

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

Precipitation15.6 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: Theodore Roosevelt Airport, ND (11 mi away); precipitation: Theodore Roosevelt Airport, ND (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.

586224b

Belfield, ND · 13 mi

586014b

Dickinson, ND · 14 mi

586024a

Dickinson, ND · 14 mi

586474b

New England, ND · 18 mi

586204b

Amidon, ND · 23 mi

586304a

Gladstone, ND · 24 mi

North Dakota planting zones →

Questions about 58655

What planting zone is ZIP code 58655?

ZIP code 58655 (South Heart, ND) 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 South Heart, ND?

The median last spring frost (32 °F) near 58655 is May 18; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Theodore Roosevelt Airport station.

When is the first frost in South Heart, ND?

The median first fall frost near 58655 is September 25, giving a median frost-free growing season of 129 days.

When should I plant tomatoes in 58655?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 58655 get?

About 15.6 inches of precipitation a year (NOAA 1991–2020 normals, Theodore Roosevelt Airport station).

How hot do summers get in South Heart, ND?

The average high peaks at 84 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 58655 have?

The USDA soil survey maps Daglum at the center of ZIP 58655: silt loam, moderately well drained, pH about 6.6 (neutral).

Did spring come early in South Heart, ND in 2026?

Spring leaf-out near 58655 came on Apr 8 in 2026, 10 days earlier than the 1991–2020 average (Apr 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in South Heart, ND?

Long-day onions: the longest day near 58655 is 15 h 52 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 58655 change?

Yes. The 2012 USDA map put 58655 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.