Southern plants find fertile ground farther north as climate changes in the U.S.

By Janice Lloyd, USA TODAY
26 January 2012 Southern magnolias, lovers of sultry weather, braving the chillier Northeast? Camellias, a New Orleans trademark, staking out in North Carolina and higher latitudes? It’s true, gardening experts say, and expect similar oddities to represent the new norm. It is now safe to plant new species in many parts of the nation, according to a new government map released Wednesday showing new growing guidelines for the first time in decades. A gradual northward warming trend makes it possible to plant trees and other perennials that would have perished in colder zones. The “hardiness” zones, the gospel to the nation’s 82 million gardeners that are printed on the back of seed packs and catalogs, are based on average minimum temperatures. “It is a good thing the government has updated the map,” says Woodrow Nelson, director of marketing communications for the Arbor Day Foundation. “Our members have been noticing these climate changes for years and have been successfully growing new kinds of trees in places they wouldn’t grow before.” For example, Pennsylvania’s growing zone was considered risky for southern magnolias, according to the old government map dating to 1990. But the new map, based on updated weather statistics from 1996 to 2005, puts Pennsylvania, like much of the Northeast, in a warmer growing zone. Catherine Woteki, an undersecretary of the Department of Agriculture, which issued the new guidelines, cautioned against reading too much into the changes. “We do not think the plant hardiness zone methodology is appropriate for making comments on climate change,” she says. Might gardeners be going out on a limb? Steve Carroll, director of public programs at the State Arboretum in Virginia, advises gardeners to check with their local nurseries or a university extension program for advice. “There’s definitely a changing climate,” says Charlie Nardozzi, a gardening consultant in northern Vermont. “But that doesn’t mean we won’t have a harsh winter again that could kill all their plants.”