An updated Hardiness Zone Map for Dallas-Fort Worth, Texas is available.

Dallas-area gardeners have known for a long time that the region is warmer than USDA Zone 7.The updated Plant Hardiness Zone Map was released by the government on January 25.

For more than a decade, central Dallas was considered Zone 8a by local garden experts.Zone 8a is the area north of the Red River.

An update of the official guide for 80 million gardeners shows that the day that is the most cold in the year isn't as cold as it used to be.

The average annual extreme minimum temperature in Zone 8a is between 10 and 15 degrees.The map doesn't measure how hot it gets, which is relevant to a plant's survival in Texas.

Kim Kaplan, who was part of the map team, tried to distance the new zones from global warming issues.She said that the map is not a good instrument to demonstrate climate change because it is based on just the hottest days of the year.