The USDA plans to release a revised “Plant Hardiness Map” any day now, based on more recent climate data. A horticulturalist on the advisory committee for this project posted this article about the history of that map, with some previews of the new one. You can read it here:http://www.plantdelights.com/Tony/hardiness.html
He mentions the map is likely to reflect that some parts of the country have warmed up to 7 degrees since its last iteration, in 1990. That doesn’t necessarily mean Minnesota is becoming a tropical, palm-lined hothouse. But it does mean that what might not have thrived in some regions before will do just fine now.
Meanwhile, Project Budburst enters its second year, inviting observers and backyard naturalists from all over the country to report when more than 30 plant species bud and flower. The data they collect will tell scientists how these plants are responding to climate change – and early results are that many of them are budding earlier.