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.
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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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: USDA PLANTS Database / Growable Ground plant catalog. 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.
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 (USDA PLANTS 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: USDA PLANTS Database. 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 and drainage requirements from USDA PLANTS Database. Ohio soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Black Seed in Ohio — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 5-10 (USDA PLANTS Database)
- State Zones: 5b-7a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 5 - Apr 13 to Oct 31 - Nov 6 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 100 days
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.
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):
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). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Black Seed mature before first frost in Ohio?
Yes — Black Seed matures in 100 days (USDA PLANTS 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:
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