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Counties with the Widest Hardiness Range

Published May 2, 2026

Some counties span surprisingly wide hardiness ranges due to elevation changes, microclimates, and topographic variation. A single county might contain valley bottoms suitable for zone 8 plants and mountain ridges where only zone 5 species survive. This diversity creates both challenges and opportunities for gardeners.

We identified the counties with the widest hardiness zone ranges, where elevation and geography create multiple growing climates within a single county boundary.

Counties with the Widest Hardiness Range

Autauga County, AL spans a 0°F hardiness range (8b), meaning a single county can contain growing conditions equivalent to multiple hardiness zones.

RankCountyStateZoneRangeSpread (°F)
1Autauga CountyAL8b8b0
2Baldwin CountyAL9a8b-9a0
3Barbour CountyAL8b8b0
4Bibb CountyAL8a8a-8b0
5Blount CountyAL8a8a0
6Bullock CountyAL8b8b0
7Butler CountyAL8b8b0
8Calhoun CountyAL8a8a0
9Chambers CountyAL8a8a-8b0
10Cherokee CountyAL8a8a0
11Chilton CountyAL8b8a-8b0
12Choctaw CountyAL8b8b0
13Clarke CountyAL8b8b0
14Clay CountyAL8a8a0
15Cleburne CountyAL8a8a0
16Coffee CountyAL8b8b0
17Colbert CountyAL8a7b-8a0
18Conecuh CountyAL8b8b0
19Coosa CountyAL8a8a0
20Covington CountyAL8b8b-9a0
21Crenshaw CountyAL8b8b0
22Cullman CountyAL8a7b-8a0
23Dale CountyAL8b8b-9a0
24Dallas CountyAL8b8b0
25DeKalb CountyAL8a7b-8a0

Note

When a county has a wide hardiness range, always check your specific elevation and microclimate. A valley garden may be two full zones warmer than a ridge-top property just a few miles away.

Methodology

Counties ranked by the temperature spread within their USDA hardiness zone range. Data from USDA PHZM 2023.

Data sourced from USDA Plant Hardiness Zone Map (2023) and USDA SSURGO Soil Survey. Hardiness zone data represents average annual extreme minimum temperatures and should be used as a general guide. Local microclimates may vary significantly from county averages.

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