Miami County, in Ohio, sits in USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with tomato, sweet corn, apple, and pawpaw — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Miami County holds more than one microclimate.
Soils and elevations shift across Miami County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
6a
Last Hard Freeze (28°F)
Mar 19
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 22
County normal — light frosts arrive a few weeks earlier
County Area
260K acres
Hardiness Zone Range
Zone maps are averages across Miami County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Miami County
Across Miami County, the ground is predominantly Alfisols, where Crosby, Miamian, and Celina are the most extensive named soil series. The soil is generally somewhat poorly drained with a silt loam surface. Topsoil pH runs about 6.2–6.5, slightly acidic. Rainfall drains through hydrologic group C/D soils.
Soil order
Alfisols
Drainage
Somewhat poorly drained
Prime farmland
34%
Hydric soils
17%
Soil still varies lot by lot — soil types explained.
What Grows in Miami County
Plants matched to Miami County's USDA zones 6a — each links to its full growing profile.
Is it too late to plant in Miami County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 22 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Growing Challenges in Ohio
What an experienced grower plans around here — each one has a move.
Heavy clay soils across much of northern Ohio require amendment for drainage
A raised bed fixes the drainage in one weekend — and amended clay repays the effort as some of the richest soil there is.
Variable spring weather with late frost risk through mid-May
Watch your local last-frost normal, not the region's — holding tender plants two extra weeks beats replanting a bed.
Japanese beetles and tomato hornworms are common garden pests
Hand-pick early, row-cover young plants, and skip broad sprays — extension IPM guides keep the beneficial insects on your side.
Wet springs can delay planting and promote root rot
Raised or mounded rows shed spring water and warm earlier — where puddles linger, drainage is the first project worth doing.
For cultivar selection, pest pressure, and planting-time guidance specific to Ohio, the Ohio State University Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Miami County — and how to grow with it.
We checked the federal record across Miami County — 491 documented sites across 6 of the 9 source types we track.
The most significant on record: 10 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Miami County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Miami County
Severity Distribution
across Miami County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Miami County, two things run higher than the national average — Toxic Release Inventory (52 sites) and Superfund (10 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxic Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Miami County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Miami County Average
- ●USDA Zones 6a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Miami County
Pull a site-specific report for your exact address in Miami County, Ohio — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Miami County, Ohio
- USDA Hardiness Zones: 6a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Mar 19 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 22 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~248 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 260K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Miami County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Miami County, Ohio?
Miami County sits in USDA hardiness zone 6a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Miami County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 22 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
When does frost risk typically end in Miami County?
The last hard freeze (28°F) in Miami County typically lands around Mar 19, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Miami County?
Measured between 28°F hard freezes, Miami County sees about 248 frost-free days — roughly Mar 19 through Nov 22, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Miami County?
Miami County's zone 6a supports a wide range — strong performers include Tomato, Sweet Corn, Apple, Pawpaw, and Buckeye. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Miami County, really?
Officially, Miami County sits in USDA zone 6a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Miami County?
The federal record around Miami County runs heavier than most — 491 documented sites — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Just moved to Miami County — what should I know before planting?
Start with three facts. Miami County sits in USDA zone 6a, which sets what survives winter; the last 28°F hard freeze typically clears around Mar 19, with about 248 frost-free days to work with (NOAA 1991–2020 climate normals); and 491 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Miami County average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Ohio's frost window, season length, and soil profile against the plant's real requirements.