Delaware Plant Hardiness Zones
Delaware’s towns run from zone 7a to zone 8a: the average coldest winter night is 11.3°F at Rehoboth Beach and 4.3°F at North Star.
Hardiness zones in Delaware
In USDA’s colors, neighboring states washed out. Zones follow elevation, coasts and cities down to half a mile. Drawn by WeatherOverTime from the USDA-ARS and Oregon State University PRISM Climate Group 2023 GIS data; this is not the official USDA Plant Hardiness Zone Map.
- 7a
- 7b
- 8a
Towns by zone
Each town’s 1991-2020 average annual extreme minimum at its center, read from the map’s 800 m grid. Warmest zone first.
8a Zone 8a, 10 to 15°F 4 towns
7b Zone 7b, 5 to 10°F 50 towns
- Bear6.7°F
- Bellefonte7.6°F
- Blades6.5°F
- Bridgeville6.6°F
- Brookside6.3°F
- Camden7.1°F
- Cheswold6.6°F
- Claymont8.7°F
- Clayton6.9°F
- Dagsboro6.9°F
- Delaware City7.9°F
- Delmar7.2°F
- Dover7.7°F
- Dover Base Housing8.3°F
- Edgemoor9°F
- Elsmere6.9°F
- Felton6.7°F
- Frankford6.8°F
- Frederica7.6°F
- Georgetown6.8°F
- Glasgow6.1°F
- Greenville5.9°F
- Greenwood6.5°F
- Harrington6.2°F
- Highland Acres7.8°F
- Kent Acres7.6°F
- Laurel6.1°F
- Long Neck9.3°F
- Middletown6.4°F
- Milford6.9°F
- Millsboro6.7°F
- Millville9.3°F
- Milton7.1°F
- Nassau9.6°F
- New Castle7.3°F
- Newark5.8°F
- Newport6.9°F
- Pike Creek5.4°F
- Pike Creek Valley5.4°F
- Rising Sun-Lebanon7.6°F
- Riverview7°F
- Rodney Village7.5°F
- Seaford6.6°F
- Selbyville7°F
- Smyrna7°F
- Townsend6.7°F
- Wilmington8°F
- Wilmington Manor7.2°F
- Woodside East7.2°F
- Wyoming7°F
7a Zone 7a, 0 to 5°F 2 towns
Counties
At the county’s center; a county with hills or a coast spans several zones.
| County | Zone at the center | Average coldest night |
|---|---|---|
| Kent County | 7b | 7.6°F |
| New Castle County | 7b | 6.9°F |
| Sussex County | 7b | 6.9°F |
The zones
A plant hardiness zone is set by the average of each winter’s single coldest temperature, 1991 to 2020: zones are 10°F apart and each half zone, a and b, 5°F. It says how cold a winter night usually gets, not the coldest it has ever been, and nothing about summer heat, rain or soil. Plant labels give the coldest zone a perennial survives in.
| Zone | Average coldest night | In Celsius |
|---|---|---|
| 7a | 0 to 5°F | -17.8 to -15.0°C |
| 7b | 5 to 10°F | -15.0 to -12.2°C |
| 8a | 10 to 15°F | -12.2 to -9.4°C |
Sources
Hardiness zones: USDA Plant Hardiness Zone Map, 2023, Agricultural Research Service, U.S. Department of Agriculture, from the GIS data of the PRISM Climate Group, Oregon State University, which may be freely reproduced and redistributed. Drawn by WeatherOverTime from the USDA-ARS and Oregon State University PRISM Climate Group 2023 GIS data; this is not the official USDA Plant Hardiness Zone Map.