Ohio Planting Zones and Frost Dates by County

Every Ohio ZIP code on the USDA map is in hardiness zone 6a, 6b or 7a. 45 counties are mostly zone 6b, 42 counties are mostly zone 6a and Lawrence County is mostly zone 7a, and parts of 9 more reach 7a (Clermont, Cuyahoga, Erie, Gallia, Jefferson, Lake, Lorain, Ottawa and Scioto). The average last spring freeze runs from April 9 in Hamilton County to May 5 in Trumbull County.

Ohio planting zone map by county

Zone 6a Zone 6b Zone 7a (each county by its most common ZIP-code zone)

USDA Plant Hardiness Zone Map (2023), by ZIP code, from the PRISM Climate Group, Oregon State University, accessed Nov. 8, 2026; rolled up to counties by Dayton Report. A zone is the average coldest winter night, 1991–2020.

Last frost date in Ohio, by county

Average last spring and first fall freeze (32°F) dates, 1991–2020, and the growing season between them. These are county-wide estimates: each day’s low temperature averaged across the county, then the last spring and first fall day at or below freezing in each year, averaged over 30 years. A single spot, especially a low one, can freeze later in spring or earlier in fall.

Last freeze: average last spring day at or below 32°F; first freeze: average first fall one; days: the growing season between them. Freeze dates: PRISM daily minimum temperature, averaged over each county, through NOAA’s Regional Climate Centers (RCC-ACIS), 1991-2020.

When to plant tomatoes in Ohio

Ohio State University Extension advises setting tomatoes out after the danger of frost has passed, and gives about May 20 as central Ohio’s last frost for planting purposes; with frost protection, gardeners can plant about a week earlier. That’s later than the average last freeze in the table above on purpose: an average date still brings a freeze afterward in many years, and tomatoes are damaged by cold nights well above freezing. (Ohio State University Extension, Growing Tomatoes in the Home Garden (HYG-1624))

Peppers and cabbage

Peppers: start seeds indoors 8 to 10 weeks before transplanting (counted back from central Ohio’s May 20, that’s March 11 to March 25), and set plants out after frost danger, once nights stay above 55°F; peppers aren’t seeded directly in the garden in Ohio. (Ohio State University Extension, Growing Peppers in the Home Garden (HYG-1618)) Cabbage: start seeds indoors 6 to 8 weeks before the frost-free date. (Ohio State University Extension, Growing Cabbage in the Home Garden (HYG-1611))

For the Dayton area’s rainfall, records and frost dates from each county’s weather station, see the Miami Valley Weather Almanac.