The map is based on 30-year averages of the coldest winter temperatures at specific locations, and divides the continental U.S. and Canada into 10 zones, which are further divided into half-zones.

The new version of the map includes 13 zones, with the addition for the first time of zones 12 (50-60 degrees F) and 13 (60-70 degrees F). U.S. Department of Agriculture hide caption ...

Natural Resources Canada is hoping to release an updated version of Canada's plant hardiness zones map in 2024. The last time it was updated was in 2014. Skip to Main Content ...

It's a frost date interactive map by zip code throughout the United States and Canada. Knowing the last frost date is a game-changer because if you plant before the last frost hits, you can risk ...

The USDA 2012 Plant Hardiness Zone Map. USDA The USDA Plant Hardiness Zone Map divides the United States and Canada into 13 zones, based on the average annual minimum winter temperature.

The new one offers an interactive format and looks at 30 years of weather patterns, showing that in some cases - Ohio, Nebraska and Texas - nearly entire states have been updated to warmer zones.

For example, the coldest hardiness zone in the lower 48 states on the new map, 3a, covers small pockets in the northernmost parts of Minnesota and has winter extreme temperatures of -40 F to -35 F.

The USDA is updating an important map for gardeners and growers picking plants and flowers. The new map shows the contiguous U.S. is about 2.5 degrees Fahrenheit warmer than the last map 11 years ago.

In the 2012 map, many zone boundaries have shifted significantly. Some of the shifting zone boundaries, they said, were the result of more sophisticated mapping.