Overall, the map generally shows warmer winter low temperatures than the 1990 map. "It reflects a new reality: The coldest day of the year isn't as cold as it used to be, so some plants and trees can now survive farther north," AP reports.
An updated map that will likely be familiar to anyone who has planted a packet of seeds was presented last week by the U.S. Department of Agriculture (USDA). This is the first new version of the Plant Hardiness Zone Map since 1990.
The government is "catching up with what the plants themselves have known for years now: The globe is warming and it is greatly influencing plants," Stanford University biology professor Terry Root told the Associated Press.
The map has "greater accuracy and detail" according to a USDA press release, thanks in part to 30-years of temperature data. The map also shows America's climate is changing.
Compared to the 1990 version, zone boundaries in this edition of the map have shifted in many areas. The new map is generally one 5-degree Fahrenheit half-zone warmer than the previous map throughout much of the United States.