Gardeners aren't surprised as USDA updates key map Boggs notes you can toggle between the 2012 and 2023 maps on the USDA's website. "There are dramatic changes," he says.

According to the USDA, the map is also based on 30-year averages of the lowest annual winter temperatures at the specific locations, and split into 10-degree and 5-degree zones and integrates data ...

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.

USDA spokeswoman Kim Kaplan, who was part of the map team, repeatedly tried to distance the new zones in the map from global warming issues. She said even though much of the country is in warmer ...