The new map, created by USDA's Agricultural Research Service and Oregon State University, is based on 30 years of data from 13,412 weather stations, almost twice as many as the old map.

The USDA map has been updated four times since 1960. A version released in 1990 introduced a new warmer zone, zone 11. But that map was based on only 13 years of weather data (1974–1986), and it just ...

There are 13 full zones ... The USDA draws the map using a color-coded key for easier reference. Though it was last updated in 2012, the previous map used weather data from 1974 to 1986.

For example, Seattle, Washington, and the city of Austin, Texas, are both in the USDA hardiness zone 9a because the map is a measure of the coldest temperature a plant can handle.

One of the major changes in this year’s edition of the hardiness map is the zone boundaries. The USDA states that the new zones are generally about one-quarter-zone warmer than reported in 2012 ...

What the new USDA plant hardiness map means for your garden Published November 21, 2023 at 4:00 AM EST ... It's a full hour of gardening plus your phone calls. Guests: ...

Each full zone is also divided into half zones. The USDA draws the map using a color-coded key for easier reference. Though it was last updated in 2012, ...

The map and its zone system are designed to help gardeners and farmers understand a plant’s ability to survive the winter and thrive where they live. 1 weather alerts 1 closings/delays.