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

Planting zone for 45321 — Eldorado, OH

ZIP code 45321 (Eldorado, Preble County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 25 and the first fall frost October 20.

Where ZIP 45321 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 25
First frostOct 20
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 Eldorado, 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 Eldorado, OH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 10only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 6
Growing season176 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around October 30.

From the NOAA station Eaton, OH — 9 miles away, elevation 1,001 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 45321

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 25 – Sep 8
GarlicPlant cloves · Oct 6 – Nov 10
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 20) 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 45321 came on Mar 10 — 20 days earlier than the 1991–2020 average (Mar 30).

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.

Trees 70

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 109

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 202

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °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 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °F

Grasses 164

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 8

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 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Eldorado, OH.

Soil in Eldorado, OH

The soil mapped at the center of ZIP 45321 is Crosby — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2.5%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classPrime farmland if drainedUSDA classification

Map unit: Crosby-Celina silt loams, 2 to 4 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 45321; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Eldorado, OH

Summer high85 °Faverage high, July
Winter low17 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,205base 50 °F — the season’s usable heat
Longest day15 h 00 mindaylight on June 21
Shortest day9 h 20 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation42.1 inper year, rain and melted snow
Snowfall12 inper year; 15 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 35 °F, low 17 °F 35°17° JanFebruary: average high 40 °F, low 19 °F 40°19° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 63 °F, low 38 °F 63°38° AprMay: average high 73 °F, low 49 °F 73°49° MayJune: average high 82 °F, low 59 °F 82°59° JunJuly: average high 85 °F, low 62 °F 85°62° JulAugust: average high 84 °F, low 60 °F 84°60° AugSeptember: average high 79 °F, low 53 °F 79°53° SepOctober: average high 66 °F, low 41 °F 66°41° OctNovember: average high 52 °F, low 31 °F 52°31° NovDecember: average high 41 °F, low 23 °F 41°23° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.28 in precipitation, 6 in snowfall 3.3❄6 JanFebruary: 2.35 in precipitation, 1.8 in snowfall 2.4❄2 FebMarch: 3.41 in precipitation, 2.4 in snowfall 3.4❄2 MarApril: 4.24 in precipitation, 0.2 in snowfall 4.2 AprMay: 4.45 in precipitation 4.5 MayJune: 4.74 in precipitation 4.7 JunJuly: 3.97 in precipitation 4.0 JulAugust: 3.24 in precipitation 3.2 AugSeptember: 3.17 in precipitation 3.2 SepOctober: 3.10 in precipitation, 0.1 in snowfall 3.1 OctNovember: 3.13 in precipitation, 0.3 in snowfall 3.1 NovDecember: 3.03 in precipitation, 1.6 in snowfall 3.0❄2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Eaton, OH (9 mi away); precipitation: W Manchester 3 Wsw, OH (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

453476a
New Paris, OH · 4 mi
453826a
West Manchester, OH · 5 mi
453386a
Lewisburg, OH · 8 mi
453206a
Eaton, OH · 8 mi
453466a
New Madison, OH · 8 mi
453326a
Hollansburg, OH · 10 mi
453786a
Verona, OH · 11 mi
473746a
Richmond, IN · 11 mi

Ohio planting zones →

Questions about 45321

What planting zone is ZIP code 45321?

ZIP code 45321 (Eldorado, 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 Eldorado, OH?

The median last spring frost (32 °F) near 45321 is April 25; after May 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eaton station.

When is the first frost in Eldorado, OH?

The median first fall frost near 45321 is October 20, giving a median frost-free growing season of 176 days.

When should I plant tomatoes in 45321?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 45321 get?

About 42.1 inches of precipitation a year and 12 inches of snowfall (NOAA 1991–2020 normals, W Manchester 3 Wsw station).

How hot do summers get in Eldorado, OH?

The average high peaks at 85 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 45321 have?

The USDA soil survey maps Crosby at the center of ZIP 45321: silt loam, somewhat poorly drained, pH about 6.2 (slightly acidic).

Did spring come early in Eldorado, OH in 2026?

Spring leaf-out near 45321 came on Mar 10 in 2026, 20 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Eldorado, OH?

Long-day onions: the longest day near 45321 is 15 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 45321 change?

Yes. The 2012 USDA map put 45321 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.