Southern staples like magnolia trees and camellias may now be able to grow without frost damage in once-frigid Boston.
The U.S. Department of Agriculture’s ” plant hardiness zone map ” was updated Wednesday for the first time in a decade, and it shows the impact that climate change will have on gardens and yards across the country.
Climate shifts aren’t even—the Midwest warmed more than the Southeast, for example. But the map will give new guidance to growers about which flowers, vegetables and shrubs are most likely to thrive in a particular region.
One key figure on the map is the lowest likely winter temperature in a given region, which is important for determining which plants may survive the season. It’s calculated by averaging the lowest winter temperatures of the past 30 years.
Across the lower 48 states, the lowest likely winter temperature overall is 2.5 degrees (1.4 degrees Celsius) warmer than when the last map was published in 2012, according to Chris Daly, a researcher at Oregon State University’s PRISM Climate Group, which collaborates with the USDA’s Agricultural Research Service to produce the map.
Boston University plant ecologist Richard Primack, who was not involved in the map project, said, “Half the U.S. has shifted to a slightly warmer climatic zone than it was 10 years ago.” He called that “a very striking finding.”
Primack said he has noticed changes in his own garden: The fig trees are now surviving without extensive steps to protect them from winter cold. He has also spotted camellias in a Boston botanical garden and southern magnolia trees surviving the past few winters without frost damage. These species are all generally associated with warmer, more southern climates.
I have had a vegetable garden in the same spot northwest of Boston for 36 years. On average I can plant 1.5-2 weeks earlier and harvest 1.5-2 weeks later now compared to 1987. Last year was a anomaly and picked my last vegetables on Nov 13th.
Might as well take advantage of this heating and try fig trees again. If it wasn’t the cold that got them it was all mouse hotels that I created protecting the base and roots from the cold.
Along with the average warming advantages, the increase in periods of extreme heat hammer the hell out of vegetation. Have observed this on a worrying number of occasions in Oz this century. Am wondering about crops like Canadian winter wheat ( and in the USA?? ). This is a food crop, of Global Significance, that suffers in warm winters. Laypersons understanding.
World is warming and will cook. By how much depends.