A new plant hardiness map indicates much of northern Ohio is getting warmer.

The U.S. Department of Agriculture today unveiled an updated version of its plant hardiness zone map that puts most of the state in Zone 6A, meaning the average minimum temperature is 5 to 10 degrees below zero. Previously much of northern Ohio was in the slightly colder Zone 5B, while the southern half of the state was mostly in Zone 6A.

Bottom line for gardeners: Plants that once struggled or died during the winter have a better chance of surviving.

USDA spokeswoman Kim Kaplan, however, cautioned that the new map cannot be considered evidence of climate change. It’s based on only 30 years’ worth of weather data, which isn’t enough time to prove a trend, she said. What’s more, she noted that only a half-degree difference in average minimum temperature could be enough to push an area into a new zone.

Developers of the new map were able to use more sophisticated technology, so the map is far more detailed and accurate than previous versions, Kaplan said. They started with weather data collected from points across the United States and then applied an algorithm that considered such factors as slope, elevation, prevailing winds and nearness to large bodies of water. As a result, they were able to determine minimum temperatures between the data-collection points and produce a map that pinpoints differences on a much finer scale.

The map is interactive. Type in a ZIP code to find out what zone most of your  postal area falls in, or click on the interactive map to zoom in more closely to your neighborhood.