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

Planting zone for 45817 — Bluffton, OH

ZIP code 45817 (Bluffton, Allen County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 23 and the first fall frost October 22.

Where ZIP 45817 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 23

First frostOct 22

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Bluffton, 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 Bluffton, OH

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 23median — 50% chance of a later frost

Safe for tender plantsMay 9only 10% chance of frost after

First fall frostOctober 22median — 10% chance by Oct 6

Growing season180 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around November 2.

From the NOAA station Pandora, OH — 6 miles away, elevation 771 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 45817

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 12 – Mar 26

SpinachSow outdoors · Mar 12 – Apr 2

Broccoli, cabbageStart indoors · Feb 12 – Feb 26

Broccoli, cabbageTransplant · Apr 2 – Apr 16

Onion setsPlant outdoors · Mar 26 – Apr 9

PotatoesPlant outdoors · Apr 2 – Apr 16

LettuceSow outdoors · Mar 26 – Apr 9

Carrots, beetsSow outdoors · Apr 2 – Apr 16

TomatoesStart indoors · Feb 26 – Mar 12

TomatoesTransplant · Apr 30 – May 14

Peppers, eggplantStart indoors · Feb 12 – Feb 26

Peppers, eggplantTransplant · May 7 – May 21

BeansSow outdoors · Apr 30 – May 14

Sweet cornSow outdoors · Apr 30 – May 14

Cucumbers, squashSow outdoors · Apr 30 – May 14

Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10

GarlicPlant cloves · Oct 8 – Nov 12

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 22) 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 45817 came on Mar 12 — 21 days earlier than the 1991–2020 average (Apr 2).

average
Apr 22026
Mar 12

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 Bluffton, OH.

Soil in Bluffton, OH

The soil mapped at the center of ZIP 45817 is Glynwood — clay loam, moderately well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH6.2slightly acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Glynwood clay loam, ground moraine, 6 to 12 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 45817; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bluffton, OH

Summer high84 °Faverage high, July

Winter low19 °Faverage low, January

Hot days14days a year at 90 °F or more

Freezing nights124nights a year at 32 °F or less

Growing degree days3,272base 50 °F — the season’s usable heat

Longest day15 h 07 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)

Precipitation38.7 inper year, rain and melted snow

Snowfall33 inper year; 40 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: Pandora, OH (6 mi away); precipitation: Pandora, OH (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

Mount Cory, OH · 7 mi

Benton Ridge, OH · 10 mi

Ohio planting zones →

Questions about 45817

What planting zone is ZIP code 45817?

ZIP code 45817 (Bluffton, 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 Bluffton, OH?

The median last spring frost (32 °F) near 45817 is April 23; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pandora station.

When is the first frost in Bluffton, OH?

The median first fall frost near 45817 is October 22, giving a median frost-free growing season of 180 days.

When should I plant tomatoes in 45817?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 45817 get?

About 38.7 inches of precipitation a year and 33 inches of snowfall (NOAA 1991–2020 normals, Pandora station).

How hot do summers get in Bluffton, OH?

The average high peaks at 84 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 45817 have?

The USDA soil survey maps Glynwood at the center of ZIP 45817: clay loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Bluffton, OH in 2026?

Spring leaf-out near 45817 came on Mar 12 in 2026, 21 days earlier than the 1991–2020 average (Apr 2), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Bluffton, OH?

Long-day onions: the longest day near 45817 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).