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

Planting zone for 68634 — Duncan, NE

ZIP code 68634 (Duncan, Platte County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 21 and the first fall frost October 15.

Where ZIP 68634 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostApr 21
First frostOct 15
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Duncan, NE…

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 Duncan, NE

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 21median — 50% chance of a later frost
Safe for tender plantsMay 5only 10% chance of frost after
First fall frostOctober 15median — 10% chance by Sep 30
Growing season174 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 24.

From the NOAA station Columbus 3 Ne, NE — 11 miles away, elevation 1,450 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 68634

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 10 – Mar 24
SpinachSow outdoors · Mar 10 – Mar 31
Broccoli, cabbageStart indoors · Feb 10 – Feb 24
Broccoli, cabbageTransplant · Mar 31 – Apr 14
Onion setsPlant outdoors · Mar 24 – Apr 7
PotatoesPlant outdoors · Mar 31 – Apr 14
LettuceSow outdoors · Mar 24 – Apr 7
Carrots, beetsSow outdoors · Mar 31 – Apr 14
TomatoesStart indoors · Feb 24 – Mar 10
TomatoesTransplant · Apr 28 – May 12
Peppers, eggplantStart indoors · Feb 10 – Feb 24
Peppers, eggplantTransplant · May 5 – May 19
BeansSow outdoors · Apr 28 – May 12
Sweet cornSow outdoors · Apr 28 – May 12
Cucumbers, squashSow outdoors · Apr 28 – May 12
Fall lettuce, spinachSow outdoors · Aug 20 – Sep 3
GarlicPlant cloves · Oct 1 – Nov 5
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 21) and first fall frost (Oct 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 68634 came on Mar 11 — 22 days earlier than the 1991–2020 average (Apr 2).

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 5b in Nebraska

420 plants native to the lower 48 states, recorded in Nebraska, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 31

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Fbitternut hickory75 ft · blooms mid spring · high shade tolerance · to −47 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack oak80 ft · blooms early spring · medium shade tolerance · to −30 °F

Shrubs 55

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 190

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 130

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbasin wildrye5 ft · blooms early spring · high shade tolerance · to −43 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °F

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 Duncan, NE.

Soil in Duncan, NE

The soil mapped at the center of ZIP 68634 is Thurman — loamy fine sand, somewhat excessively drained.

TextureLoamy fine sanddrains and warms fast; dries out and needs more feeding
pH6.5neutral; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Thurman loamy fine sand, 2 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 68634; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Duncan, NE

Summer high87 °Faverage high, July
Winter low14 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights141nights a year at 32 °F or less
Growing degree days3,433base 50 °F — the season’s usable heat
Longest day15 h 10 mindaylight on June 21
Shortest day9 h 11 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation27.9 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 32 °F, low 14 °F 32°14° JanFebruary: average high 37 °F, low 18 °F 37°18° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 62 °F, low 39 °F 62°39° AprMay: average high 73 °F, low 51 °F 73°51° MayJune: average high 83 °F, low 62 °F 83°62° JunJuly: average high 87 °F, low 66 °F 87°66° JulAugust: average high 84 °F, low 64 °F 84°64° AugSeptember: average high 77 °F, low 55 °F 77°55° SepOctober: average high 63 °F, low 41 °F 63°41° OctNovember: average high 48 °F, low 28 °F 48°28° NovDecember: average high 36 °F, low 18 °F 36°18° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.54 in precipitation 0.5 JanFebruary: 0.47 in precipitation 0.5 FebMarch: 1.49 in precipitation 1.5 MarApril: 2.80 in precipitation 2.8 AprMay: 4.62 in precipitation 4.6 MayJune: 4.36 in precipitation 4.4 JunJuly: 3.34 in precipitation 3.3 JulAugust: 3.43 in precipitation 3.4 AugSeptember: 2.59 in precipitation 2.6 SepOctober: 2.28 in precipitation 2.3 OctNovember: 1.31 in precipitation 1.3 NovDecember: 0.65 in precipitation 0.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Columbus 3 Ne, NE (11 mi away); precipitation: Columbus 4.3 Sw, NE (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

686015b
Columbus, NE · 7 mi
686025b
Columbus, NE · 8 mi
686475b
Monroe, NE · 11 mi
686635b
Silver Creek, NE · 11 mi
686515b
Osceola, NE · 12 mi
686535b
Platte Center, NE · 12 mi
686625b
Shelby, NE · 13 mi
686405b
Genoa, NE · 14 mi

Nebraska planting zones →

Questions about 68634

What planting zone is ZIP code 68634?

ZIP code 68634 (Duncan, NE) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Duncan, NE?

The median last spring frost (32 °F) near 68634 is April 21; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Columbus 3 Ne station.

When is the first frost in Duncan, NE?

The median first fall frost near 68634 is October 15, giving a median frost-free growing season of 174 days.

When should I plant tomatoes in 68634?

Start tomato seeds indoors around Feb 24 – Mar 10 and set transplants outside around Apr 28 – May 12, one to three weeks after the median last frost.

How much rain and snow does 68634 get?

About 27.9 inches of precipitation a year (NOAA 1991–2020 normals, Columbus 4.3 Sw station).

How hot do summers get in Duncan, NE?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 68634 have?

The USDA soil survey maps Thurman at the center of ZIP 68634: loamy fine sand, somewhat excessively drained, pH about 6.5 (neutral).

Did spring come early in Duncan, NE in 2026?

Spring leaf-out near 68634 came on Mar 11 in 2026, 22 days earlier than the 1991–2020 average (Apr 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Duncan, NE?

Long-day onions: the longest day near 68634 is 15 h 10 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).