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

Planting zone for 45373 — Troy, OH

ZIP code 45373 (Troy, Miami County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 18 and the first fall frost October 23.

Where ZIP 45373 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 18

First frostOct 23

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 Troy, 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 Troy, OH

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 5only 10% chance of frost after

First fall frostOctober 23median — 10% chance by Oct 9

Growing season186 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 5 and returns around November 3.

From the NOAA station Piqua Wwtp, OH — 7 miles away, elevation 853 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 45373

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 28 – Sep 11

GarlicPlant cloves · Oct 9 – Nov 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 23) 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 45373 came on Mar 10 — 16 days earlier than the 1991–2020 average (Mar 26).

average
Mar 262026
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 Troy, OH.

Soil in Troy, OH

The soil mapped at the center of ZIP 45373 is Eldean — loam, well drained.

TextureLoama good balance for most vegetables

pH6.5neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Eldean, loam surface-Urban land complex, 0 to 2 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 45373; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Troy, OH

Summer high84 °Faverage high, July

Winter low21 °Faverage low, January

Hot days17days a year at 90 °F or more

Freezing nights111nights a year at 32 °F or less

Growing degree days3,450base 50 °F — the season’s usable heat

Longest day15 h 01 mindaylight on June 21

Shortest day9 h 19 mindaylight on December 21

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

Precipitation41.5 inper year, rain and melted snow

Snowfall12 inper year; 19 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: Piqua Wwtp, OH (7 mi away); precipitation: Tipp City, OH (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Ludlow Falls, OH · 8 mi

453596a

Pleasant Hill, OH · 8 mi

453836a

West Milton, OH · 9 mi

All 2 ZIP codes in Troy → · Ohio planting zones →

Questions about 45373

What planting zone is ZIP code 45373?

ZIP code 45373 (Troy, 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 Troy, OH?

The median last spring frost (32 °F) near 45373 is April 18; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Piqua Wwtp station.

When is the first frost in Troy, OH?

The median first fall frost near 45373 is October 23, giving a median frost-free growing season of 186 days.

When should I plant tomatoes in 45373?

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 45373 get?

About 41.5 inches of precipitation a year and 12 inches of snowfall (NOAA 1991–2020 normals, Tipp City station).

How hot do summers get in Troy, OH?

The average high peaks at 84 °F in July, with about 17 days a year at 90 °F or more.

What kind of soil does 45373 have?

The USDA soil survey maps Eldean at the center of ZIP 45373: loam, well drained, pH about 6.5 (neutral).

Did spring come early in Troy, OH in 2026?

Spring leaf-out near 45373 came on Mar 10 in 2026, 16 days earlier than the 1991–2020 average (Mar 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Troy, OH?

Long-day onions: the longest day near 45373 is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).