Yes — Strong Match
black seed (zones 5-10) covers every zone Ohio contains (5b-7a), so hardiness is not what limits it anywhere in the state.
Black Seed in Ohio — the short answer
Black Seed in Ohio: hardy in zones 5–10, full sun, against a state median of ~208 frost-free days.
- Plant zones
- 5-10
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Ohio zones
- 5b-7a
- USDA PHZM 2023
- Frost window
- Apr 5 - Apr 13 – Oct 31 - Nov 6
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 182 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 100 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Black Seed is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Ohio site runs ~208 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score black seed against your land's actual frost dates, sun, and soil.
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Ohio is not one climate
A single Ohio answer averages 88 counties whose growing seasons are 57 days apart — from 182 frost-free days in Columbiana County to 239 in Cuyahoga County. Which end of that your land sits nearer changes what black seed can finish before the first hard freeze.
The middle half of 88 counties runs 201–214 days, with a median of 208 days — a 57-day span end to end.
Measured across 88 Ohio counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Ohio Fits Best
Even within Ohio's zones 5b-7a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for black seed (USDA PHZM 2023):
Zone Comparison
Black Seed Needs
- USDA Zones: 5-10
- Frost-Free Days: 90+
- Sun: Full Sun
- Mature size: 1.3 ft tall
- Picking window: ~21 days of harvest
- Drought tolerance: Medium
Ohio Has
- USDA Zones: 5b-7a
- Last Hard Freeze (28°F): Apr 5 - Apr 13
- First Hard Freeze (28°F): Oct 31 - Nov 6
- Annual Rainfall: 34-42 inches
- Common Soils: Glacial till, Clay loam, Silt loam
Plant Zone Range (zones 5-10)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Black Seed in Ohio
The frost window
Across Ohio, the last spring hard freeze (28°F) clears between Apr 5 and Apr 13, and the first fall hard freeze lands between Oct 31 and Nov 6 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 201-day window you can count on — up to 215 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Frost hardiness
Black Seed takes cold down to about 28°F before a freeze kills it (FAO ECOCROP), so you can plant on the early side of Ohio's window — even a few weeks before the final hard freeze. That is the point where cold damages growing tissue, not a winter-survival floor — an established perennial comes through far colder while dormant, which is what its hardiness zone tells you.
When to start the seed
Black Seed is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Ohio's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 100 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 101 days to spare even in Ohio's tightest freeze scenario — room for a later start or a second sowing.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says black seed survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Black Seed wants 90+ frost-free days; a typical Ohio site sees ~208 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Black Seed needs ~1500 GDD (base 50°F) to ripen. The state median runs ~2921 GDD (from PRISM 1991-2020 climate normals), so Ohio's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Black Seed likes near-neutral soil (pH 5.5-8). That's the common-ground band across Ohio's glacial till and clay loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7.5 — worth knowing before you decide whether a Ohio soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Ohio site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Ohio soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant black seed for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before black seed goes in. What follows is Ohio’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Ohio — and how to grow with it.
We checked the federal record across Ohio — 49,306 documented sites across 8 of the 9 source types we track.
The most significant on record: 669 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Ohio 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 Checked
across Ohio
Severity Distribution
across Ohio
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Ohio, two things run higher than the national average across Ohio — Toxics Release Inventory (4,234 sites) and Superfund (669 sites). That's not a problem with your land — it's information about 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Black Seed in Ohio
Zone compatibility tells you about winter cold survival — but Ohio growers also need to think about:
Heavy clay soils across much of northern Ohio require amendment for drainage
Variable spring weather with late frost risk through mid-May
Japanese beetles and tomato hornworms are common garden pests
Wet springs can delay planting and promote root rot
What to actually do about these — and the constraints that apply to every Ohio grower, not just black seed — is covered on the Ohio growing guide.
Timing shifts within Ohio
Black Seed needs about 90 days of frost-free season to complete its cycle. Even Columbiana County — Ohio’s shortest season at 182 frost-free days — clears that by 92 days, so season length isn’t the constraint anywhere in Ohio. What varies is your own parcel.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Black Seed's 90-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Black Seed draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, black seed can only work that bloom inside Ohio's frost window — roughly 208 days, opening after the last 28°F freeze (Apr 5 - Apr 13) and closing at the first (Oct 31 - Nov 6), per NOAA Regional Climate Centers ACIS, 1991-2020.
Ohio Cooperative Extension
For Ohio-specific cultivar recommendations, planting calendars, and pest pressure for black seed, the canonical source is Ohio State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Seed native to Ohio?
No — the USDA PLANTS Database lists Black Seed as introduced rather than native in the Lower 48, so it is not part of Ohio's native flora. It grows here as a garden plant; pairing it with a few Ohio natives keeps local pollinators fed too.
Looking for plants that belong here? The Ohio growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Black Seed in Ohio
When can I plant Black Seed in Ohio?
Ohio's last spring hard freeze (28°F) clears between Apr 5 and Apr 13, and the first fall hard freeze lands between Oct 31 and Nov 6 (NOAA Regional Climate Centers ACIS, 1991-2020). Black Seed takes cold to about 28°F before a freeze kills it (FAO ECOCROP — the point where cold damages growing tissue, not a winter-survival floor), so plant on the early side of that window — even ahead of the final hard freeze.
Can Black Seed mature before first frost in Ohio?
Yes — Black Seed matures in 100 days (Growable Ground Plant Database), and Ohio's dependable hard-freeze-free window runs 201 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 101 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Black Seed grown in across Ohio?
Ohio spans USDA hardiness zones 5b-7a (USDA ARS PHZM 2023). Black Seed carries a range of zones 5-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Ohio site have?
A typical Ohio site sees ~208 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Black Seed needs 90+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Black Seed native to Ohio?
No — the USDA PLANTS Database lists Black Seed as introduced rather than native in the Lower 48, so it is not part of Ohio's native flora. It grows here as a garden plant; pairing it with a few Ohio natives keeps local pollinators fed too.
How should I amend the soil for Black Seed in Ohio?
Black Seed prefers pH 5.5-8 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Ohio soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Black Seed actually grow on my specific land in Ohio?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black seed against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Ohio
State-level data is a sketch. Your Growable Ground report scores black seed against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Ohio black seed averages can't show:
We read public map data around Ohio — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ohio black seed average
Explore More
Growing guides for black seed
Explore Ohio county by county
Ohio carries 88 counties with their own USDA zone — a sample of the growing pages for black seed there:
Where else black seed grows
Black Seed's zone band crosses state lines — these are the states closest to Ohio in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Ohio
Ohio has a growing page for 893 plants — a rotating sample of the rest of the shelf.
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