New Hardiness Zone Map Reflects Warmer Climate

Nebraska City, Neb. (December 20, 2006)- Much of the United States has been warmer in recent years, and that affects which trees are right for planting. Based on the latest comprehensive weather station data, The National Arbor Day Foundation has just released a new 2006 Hardiness Zone Map that separates the country into ten different temperature zones to help people select the right trees to plant where they live.


The new map reflects that many areas have become warmer since 1990 when the last USDA hardiness zone map was published. Significant portions of many states have shifted at least one full hardiness zone. Much of Illinois, Indiana, and Ohio, for example, have shifted from Zone 5 to a warmer Zone 6. Some areas around the country have even warmed two full zones.

In response to requests for up-to-date information, the Arbor Day Foundation developed the new zones based on the most recent 15 years’ data available from the National Oceanic and Atmospheric Administration’s 5,000 National Climatic Data Center cooperative stations across the United States. Hardiness zones are based on average annual low temperatures using 10 degree increments. For example, the average low temperature in zone 3 is -40 to -30 degrees Fahrenheit, while the average low temperature in zone 10 is +30 to +40 degrees Fahrenheit.
“The Arbor Day Foundation supports tree planting throughout America,” says Foundation President John Rosenow. “Providing the hardiness zone for individual zip codes at arborday.org is an important part of that goal, by giving tree planters the most up-to-date and useable data available.”
“Of course existing trees should continue to be cared for,” said Woody Nelson from the Arbor Day Foundation. “Certain species may be more vulnerable to stress with the current warmer climate, but they will continue to provide environmental and economic benefits as they grow. It’s just a good idea to consider more tree species diversity for the future.”
To see suggested trees for your region and find out more information, visit the National Arbor Day Foundation.
Related Resources:
Hardiness Zone Map (zip)
Washington Warming to Southern Plants– Washington Post