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

Planting zone for 68455 — Union, NE

ZIP code 68455 (Union, Cass County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 18 and the first fall frost October 19.

Where ZIP 68455 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 18

First frostOct 19

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 Union, 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 Union, NE

JanFebMarAprMayJunJulAugSepOctNovDec

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

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

Safe for tender plantsMay 1only 10% chance of frost after

First fall frostOctober 19median — 10% chance by Oct 3

Growing season182 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around October 28.

From the NOAA station Nebraska City 2nw, NE — 8 miles away, elevation 1,056 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 68455

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 7 – Mar 21

SpinachSow outdoors · Mar 7 – Mar 28

Broccoli, cabbageStart indoors · Feb 7 – Feb 21

Broccoli, cabbageTransplant · Mar 28 – Apr 11

Onion setsPlant outdoors · Mar 21 – Apr 4

PotatoesPlant outdoors · Mar 28 – Apr 11

LettuceSow outdoors · Mar 21 – Apr 4

Carrots, beetsSow outdoors · Mar 28 – Apr 11

TomatoesStart indoors · Feb 21 – Mar 7

TomatoesTransplant · Apr 25 – May 9

Peppers, eggplantStart indoors · Feb 7 – Feb 21

Peppers, eggplantTransplant · May 2 – May 16

BeansSow outdoors · Apr 25 – May 9

Sweet cornSow outdoors · Apr 25 – May 9

Cucumbers, squashSow outdoors · Apr 25 – May 9

Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7

GarlicPlant cloves · Oct 5 – Nov 9

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 19) 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 68455 came on Mar 10 — 18 days earlier than the 1991–2020 average (Mar 28).

average
Mar 282026
Mar 10

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.

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 Union, NE.

Soil in Union, NE

The soil mapped at the center of ZIP 68455 is Monona — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.1slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.7%moderate

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Monona silt loam, 6 to 11 percent slopes, eroded.

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 68455; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Union, NE

Summer high87 °Faverage high, July

Winter low14 °Faverage low, January

Hot days30days a year at 90 °F or more

Freezing nights136nights a year at 32 °F or less

Growing degree days3,512base 50 °F — the season’s usable heat

Longest day15 h 06 mindaylight on June 21

Shortest day9 h 14 mindaylight on December 21

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

Precipitation34.1 inper year, rain and melted snow

Snowfall24 inper year; 36 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: Nebraska City 2nw, NE (8 mi away); precipitation: Nebraska City 2nw, NE (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Plattsmouth, NE · 12 mi

Weeping Water, NE · 13 mi

Nebraska planting zones →

Questions about 68455

What planting zone is ZIP code 68455?

ZIP code 68455 (Union, 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 Union, NE?

The median last spring frost (32 °F) near 68455 is April 18; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Nebraska City 2nw station.

When is the first frost in Union, NE?

The median first fall frost near 68455 is October 19, giving a median frost-free growing season of 182 days.

When should I plant tomatoes in 68455?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 68455 get?

About 34.1 inches of precipitation a year and 24 inches of snowfall (NOAA 1991–2020 normals, Nebraska City 2nw station).

How hot do summers get in Union, NE?

The average high peaks at 87 °F in July, with about 30 days a year at 90 °F or more.

What kind of soil does 68455 have?

The USDA soil survey maps Monona at the center of ZIP 68455: silt loam, well drained, pH about 6.1 (slightly acidic).

Did spring come early in Union, NE in 2026?

Spring leaf-out near 68455 came on Mar 10 in 2026, 18 days earlier than the 1991–2020 average (Mar 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Union, NE?

Long-day onions: the longest day near 68455 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).