Generally — Most Areas
crocosmia (zones 6-9) suits most of Ohio (5b-7a) — zones 6-7 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Ohio spans zones 5b-7a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score crocosmia against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Crocosmia Needs
- USDA Zones: 6-9
- Sun: Full Sun
- Mature size: 2.5 ft tall
- Picking window: ~30 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 6-9)
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 Crocosmia 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.
Winter standing
Ohio runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for crocosmia, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether crocosmia is a permanent planting or a replant-every-spring crop for you turns on your own zone within Ohio; check its hardiness range against that before treating it as long-lived ground.
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.
Soil + Drainage Fit
Crocosmia likes near-neutral soil (pH 6-7). That's the common-ground band across Ohio's glacial till and clay loam — a soil test confirms it for your site. 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.
Crocosmia in Ohio — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 6-9 (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)
What Else to Consider for Crocosmia 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 crocosmia — is covered on the Ohio growing guide.
Where in Ohio Crocosmia Is Zone-Hardy
Crocosmia is rated for USDA zones 6–9. Every one of Ohio’s 88 counties sits inside that band — from Allen County at zone 6a to Scioto County at zone 7a — so winter cold is not what decides this plant anywhere in the state. What is left to vary is your own parcel: slope, shelter and cold-air drainage routinely move a site half a zone either way from the county figure.
Across those 88 counties Ohio’s winter-low ladder runs from zone 6a in Allen County to zone 7a in Scioto County — 1 USDA zone of spread, which is 10°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Geauga County holds its last hard freeze (28°F) until about Apr 22, while Cuyahoga County is clear by Mar 30 — 23 days apart. Set crocosmia out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Crocosmia’s zone 6–9 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
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 crocosmia (USDA PHZM 2023):
Pollinator + Wildlife Value
Crocosmia draws hummingbirds and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, crocosmia 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 crocosmia, the canonical source is Ohio State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Crocosmia native to Ohio?
No — the USDA PLANTS Database lists Crocosmia 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 Crocosmia in Ohio
When can I plant Crocosmia 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). No sourced winter-hardiness floor is on record for Crocosmia, so this page does not state whether it overwinters in Ohio and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Crocosmia grown in across Ohio?
Ohio spans USDA hardiness zones 5b-7a (USDA ARS PHZM 2023). Crocosmia carries a range of zones 6-9, 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). Crocosmia should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Crocosmia native to Ohio?
No — the USDA PLANTS Database lists Crocosmia 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 Crocosmia in Ohio?
Crocosmia prefers pH 6-7 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 Crocosmia actually grow on my specific land in Ohio?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores crocosmia 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 crocosmia against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Ohio crocosmia averages can't show:
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