While earlier maps were created, the USDA hardiness zone map was first published in 1960. The hardiness zone is based on the average coldest temperature of a given region over the previous 30 years.

The USDA Plant Hardiness Zone Map uses weather data to map average annual extreme minimum temperatures (winter lows) over a recent 20-year period. The most recent release covers weather data from 1991 ...

The Plant Hardiness Zone Map is based on the average annual extreme minimum winter temperature, displayed as 10-degree F zones ranging from zone 1 (coldest) to zone 13 (warmest), the USDA notes ...

Compared to the 2012 map, the 2023 version shows that roughly half of the country shifted to the next warmer half zone, and the other half of U.S. remained in the same half zone.. According to the ...

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 ...

In 2023, the USDA released a map based on 30-year averages of the lowest annual winter temperatures at the specific locations, split into 10-degree and 5-degree zones, and integrates data from ...

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.

For the first time since 2012, a new Plant Hardiness Zone Map has been released by the U.S. Department of Agriculture. The map, released Nov. 15, 2023, is a tool used by gardeners and growers ...

The map reflects the “average lowest winter temperature” over a 30-year period at specific locations in each of the zones, according to the USDA. Overall, that average for the country was 2.5 ...

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 ...