The U.S. Department of Agriculture’s updated Plant Hardiness Zone Map that reflects an increase of about 2.5 degrees in the conterminous U.S. won’t affect nurseries as it would home gardeners.
“This could mean that those areas that shifted could potentially grow plants that are slightly less cold hardy than they previously thought,” said John Keller, vice president of production planning at Monrovia.
“We recommend consumers consult the updated map and consider their new zone (if it changed) when selecting plants,” Keller said.
“One of the best responses I’ve heard to date is that climate change doesn’t change in a day, but policy does. I think this is the right frame of mind. It doesn’t change what we grow or how we grow it. At Bailey, we evaluate the best plant on the best ground because the overarching goal for the end-user is quality and performance,” said Alec Charais, chief marketing officer at Bailey Nurseries.
“From a marketing standpoint, the new zoning might create confusion at a consumer level. New or inexperienced gardeners might attempt to grow a plant rated for their zone that is actually a marginal plant. On the other hand, plants don’t read plant tags; people do. So, if anything, this should make breeders think about how they establish the proper zone rating for their plant. I think it is too soon to say whether there will be any large changes in this area. But if it does, this updated map will have helped the industry do its best to zone plants appropriately.”
“Additionally, there are so many factors that go into the survivability of a plant in any area: water availability, temperature extremes, exposure, and placement in the landscape are just as critical to success as what zone the plant is rated for.” Charais said. “Our job as an industry is to continue to educate consumers about this and not let zone ratings be the deciding factor on whether they want to try something in their yards and enjoy the experience of gardening!”
“Overall, the 2023 map is about 2.5 degrees warmer than the 2012 map across the conterminous United States,” said the map’s lead researcher, Christopher Daly, founding director of Oregon State University’s PRISM Climate Group. “This translated into about half of the country shifting to a warmer 5-degree half zone, and half remaining in the same half zone. The central plains and Midwest generally warmed the most, with the southwestern U.S. warming very little.”
In addition to the map updates, the Plant Hardiness Zone Map website was expanded in 2023 to include a “Tips for Growers” section, which provides information about USDA ARS research programs of interest to gardeners and others who grow and breed plants. The website can be reached by going to PlantHardiness.ARS.USDA.gov. To download the updated Oregon Plant Hardiness Zone map, click here. To download the updated national map, click here.
