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

Planting zone for 45390 — Union City, OH

ZIP code 45390 (Union City, Darke County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 20 and the first fall frost October 21.

Where ZIP 45390 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostApr 20

First frostOct 21

2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Union City, OH…

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 City, OH

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 20median — 50% chance of a later frost

Safe for tender plantsMay 5only 10% chance of frost after

First fall frostOctober 21median — 10% chance by Oct 7

Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around November 1.

From the NOAA station Winchester Airport 3 E, IN — 9 miles away, elevation 1,109 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 45390

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 9 – Mar 23

SpinachSow outdoors · Mar 9 – Mar 30

Broccoli, cabbageStart indoors · Feb 9 – Feb 23

Broccoli, cabbageTransplant · Mar 30 – Apr 13

Onion setsPlant outdoors · Mar 23 – Apr 6

PotatoesPlant outdoors · Mar 30 – Apr 13

LettuceSow outdoors · Mar 23 – Apr 6

Carrots, beetsSow outdoors · Mar 30 – Apr 13

TomatoesStart indoors · Feb 23 – Mar 9

TomatoesTransplant · Apr 27 – May 11

Peppers, eggplantStart indoors · Feb 9 – Feb 23

Peppers, eggplantTransplant · May 4 – May 18

BeansSow outdoors · Apr 27 – May 11

Sweet cornSow outdoors · Apr 27 – May 11

Cucumbers, squashSow outdoors · Apr 27 – May 11

Fall lettuce, spinachSow outdoors · Aug 26 – Sep 9

GarlicPlant cloves · Oct 7 – Nov 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 20) and first fall frost (Oct 21) 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 45390 came on Mar 10 — 21 days earlier than the 1991–2020 average (Mar 31).

average
Mar 312026
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 6a in Ohio

565 plants native to the lower 48 states, recorded in Ohio, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 City, OH.

Soil in Union City, OH

The soil mapped at the center of ZIP 45390 is Pewamo — silty clay loam, very poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH6.4slightly acidic; most vegetables like 6.0–7.0

DrainageVery poorly drainedconsider raised beds

Organic matter4%moderate

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classPrime farmland if drainedUSDA classification

Map unit: Pewamo silty clay loam, 0 to 1 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 45390; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Union City, OH

Summer high83 °Faverage high, July

Winter low18 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights124nights a year at 32 °F or less

Growing degree days3,183base 50 °F — the season’s usable heat

Longest day15 h 02 mindaylight on June 21

Shortest day9 h 18 mindaylight on December 21

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

Precipitation40.1 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: Winchester Airport 3 E, IN (9 mi away); precipitation: Winchester Airport 3 E, IN (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

473906a

Union City, IN · 5 mi

New Weston, OH · 10 mi

453316a

Greenville, OH · 10 mi

453526a

Palestine, OH · 11 mi

473946a

Winchester, IN · 12 mi

453506a

North Star, OH · 12 mi

Ohio planting zones →

Questions about 45390

What planting zone is ZIP code 45390?

ZIP code 45390 (Union City, OH) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Union City, OH?

The median last spring frost (32 °F) near 45390 is April 20; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Winchester Airport 3 E station.

When is the first frost in Union City, OH?

The median first fall frost near 45390 is October 21, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 45390?

Start tomato seeds indoors around Feb 23 – Mar 9 and set transplants outside around Apr 27 – May 11, one to three weeks after the median last frost.

How much rain and snow does 45390 get?

About 40.1 inches of precipitation a year (NOAA 1991–2020 normals, Winchester Airport 3 E station).

How hot do summers get in Union City, OH?

The average high peaks at 83 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 45390 have?

The USDA soil survey maps Pewamo at the center of ZIP 45390: silty clay loam, very poorly drained, pH about 6.4 (slightly acidic).

Did spring come early in Union City, OH in 2026?

Spring leaf-out near 45390 came on Mar 10 in 2026, 21 days earlier than the 1991–2020 average (Mar 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Union City, OH?

Long-day onions: the longest day near 45390 is 15 h 02 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 45390 change?

Yes. The 2012 USDA map put 45390 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.