Ontario, Ohio, sits in USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — cabbage, hazelnut, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Ontario, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Ontario lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Ontario — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Ontario — the short answer
Ontario, Ohio: USDA zone 6a, about 203 days between hard freezes, across 7K acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 7K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 6a is Ontario's average, not your lot's — a low corner or a tree line moves it. Against Ontario's 203-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Ontario
Each reading below is measured for Ontario itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOntario runs about 203 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredOntario sits in USDA hardiness zone 6a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Ontario is in
Ontario sits in the Erie Drift Plain — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Ontario's own centroid rather than borrowed from Richland County.
What Grows in Ontario
Every plant below cleared Ontario's own zone 6a and its 203-day season. Each card opens that plant's Ohio profile. How we score.
Is it too late to plant in Ontario?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 4 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Ontario
Survey cells within 31 miles of Ontario checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 47 miles off. What to watch for.
What's on the federal record near Ontario
Closest first, within ~10 miles of Ontario. Listing isn't leaking, and distance isn't exposure.
- INVENSYS ENERGY COM TROL DIVToxics Release Inventory · 1700 ft
- BURNER SYSTEMS INTERNATIONALToxics Release Inventory · 2100 ft
- YELLOW FREIGHT SYSTEM INCBrownfields · 0.5 mi
- UNIVERSAL ENTERPRISES, INC.Underground Storage Tanks · 0.5 mi
- TRACTOR SUPPLY COMPANY #675Brownfields · 0.6 mi
- MARATHON ASHLAND PIPE LINE LLCBrownfields · 0.6 mi
- MANSFIELD FABRICATING PLANTUnderground Storage Tanks · 0.6 mi
- RACER TRUSTToxics Release Inventory · 0.6 mi
- MUSICK S SERVICE STATION MAINTBrownfields · 0.7 mi
- MID OHIO COLLISION CENTERBrownfields · 0.7 mi
- EMERSON ACTUATION TECHNOLOGIESBrownfields · 0.8 mi
- MANSFIELD MEMORIAL PARKUnderground Storage Tanks · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Ontario's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Ontario.
Total Sites
668
within ~10 miles of Ontario
Risk Level
Elevated
Highest-severity
10 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Ontario
Severity Distribution
within ~10 miles of Ontario
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Ontario, two things run higher than the national average within ~10 miles of Ontario — Toxics Release Inventory (71 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.
Toxics 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 Ontario
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Ontario average
Your land is one point inside Ontario
Everything above resolves to Ontario as a whole — one PHZM band and one 28°F frost record, read across 7K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at city scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Ontario Average
Ontario Average
- ●USDA Zones 6a, averaged across Ontario
- ●One soil character for all of Ontario
- ●Frost dates read at Ontario's scale: Apr 15 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Ontario's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Ontario
Pull a site-specific report for your exact address in Ontario, Ohio — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Ontario averages can't show:
We read public map data around Ontario — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ontario average
How we know this about Ontario
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Ontario’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Ontario
When does frost risk typically end in Ontario?
The last hard freeze (28°F) in Ontario typically lands around Apr 15, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 6.
When is the first frost in Ontario?
The first hard freeze (28°F) in Ontario typically arrives around Nov 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 21, so the watching starts about Oct 5 — about 203 days after the spring freeze cleared.
How long is the growing season in Ontario?
Measured between 28°F hard freezes, Ontario sees about 203 frost-free days — roughly Apr 15 through Nov 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 21, about 168 days.
Is the soil safe to grow vegetables in Ontario?
The federal record around Ontario is a meaningful one — 668 documented sites, mostly Underground Storage Tanks entries (308), the nearest Toxics Release Inventory record about 0.3 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Ontario?
From about Oct 5 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 4 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Ontario's scale — its 6a band and its 203-day season. Your yard writes its own version of Ontario's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Ontario’s own scale
7 of the readings below were taken at Ontario's own scale — its own ~203-day season between 28°F freezes, the 7,094 acres it covers and 668 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Ontario's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Ontario's own 28°F hard-freeze dates, about Apr 15 and Nov 4 and the ~203-day span between themNOAA 1991–2020 Climate Normals
- 668 documented contamination sites on the federal record near Ontario, the closest Toxics Release Inventory record about 0.3 miles out from the town centreFederal environmental registers
- Ontario's boundary and the 7,094 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~203-day seasonGrowable Ground crop-matching engine
- The ecoregion at Ontario's own centroid, the Erie Drift PlainUS EPA Level III Ecoregions
- Lanternfly survey cells around Ontario checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Ontario's 7,094 acres read through its county's SSURGO summaryfrom Richland County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Richland County
- The growing challenges every Ohio grower plans around — written at state scale, so they stay on the state guidefrom Ohio
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Richland County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Ontario's 7,094 acreswhy one lot differs from the next →
- Which side of Ontario you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 7,094 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory record about 0.3 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Ontario-wide figureread your own land →
More in Ohio
Wider growing context
What grows across OhioOntario sits outside our named growing regions, so Ohio as a whole is its closest context here.
Nearby growing guides