The USDA has recently released the updated 2023 Plant Hardiness Zone Map, which provides valuable information for gardeners and growers. The map indicates the average minimum low temperature that an area can experience on a yearly basis. This update is the first in over a decade and shows that the contiguous US is about 2.5 degrees Fahrenheit warmer than the previous map from 2012.

The changes in the map are not only due to a warming climate but also include more temperature data points, finer grid spacing, and an updated 30-year average temperature range. For example, the zone classification for Chicago through Sheboygan has changed from 5b to 6a, and a majority of southeast Wisconsin is now classified as 5b instead of 5a.

These changes have implications for gardeners and growers as different plants have different temperature preferences. Tropical or less hardy species are more likely to survive in higher zone classifications, while native species have a higher likelihood of survival regardless of temperature. Additionally, the map changes provide a more realistic representation of the microclimates along Lake Michigan, where water temperatures can significantly affect the local climate.

While the milder winters may allow for the survival and spread of invasive species, gardeners and growers now have the opportunity to explore new plant options that were previously unsuitable for their region. However, the excitement of discovering new possibilities is tempered by concerns about human-caused climate change and its impact on the natural world.