What it does
The USDA Plant Hardiness Zone Map helps gardeners research average annual extreme minimum winter temperatures. It offers an interactive map, ZIP-code search and downloadable regional maps.
Use this map to establish one part of a perennial-plant shortlist: the winter-temperature zone for the planting location. Enter a ZIP code or select a place on the interactive map, then record the zone before comparing plant references.
The zones use average annual extreme minimum winter temperature, with half-zone divisions. That is a specific measure, so it should not stand in for the full growing environment. The site also offers printable national, regional and state maps when a download is more convenient than the interactive view. Broadband is recommended for the GIS map, making the printable route useful for slower connections.
Strengths
- ZIP-code lookup and map selection provide two location routes
- Printable maps offer an alternative to the interactive view
Watch out for
- Winter minimum temperature describes only one aspect of a growing site
Best for
- Researching US winter hardiness before selecting perennials