What is the difference between USDA & Sunset climate zones?
In the 1960's the US Department of Agriculture began compiling information about weather records throughout the U.S. in order to show the average coldest temperatures for each region. They transformed these records into various zones of plant hardiness, and created a map showing each zone. In 1990, the USDA map was updated to create 11 USDA plant hardiness zones.
Sunset Magazine created their own 24-zone climate system over 40 years ago.
Sunset zones are more precise than USDA zones because they consider many other factors besides a region's average cold temperature, including: summer highs, elevations, proximity to mountains or coasts, rainfall, humidity, aridity, and growing seasons. These zones are specifically for the western region of the U.S.
Here at the Front Yard Nursery we label all of our plants according to the Sunset climate zones.
Placerville is in Sunset Zone 7. To find out what Sunset zone your region is click here.
Note that Sunset Climate Zones are used as guidelines for determining which plants may thrive in a given area. Other factors such as microclimates and plant location must also be considered.