USDA Agricultural Research website "What's New | USDA Plant Hardiness Zone Map" USDA's website USDA says USDA's website knowing your Zone planthardiness.ars.usda.gov knowing your Zone knowing your Zone "What's New | USDA Plant Hardiness Zone Map" knowing your Zone specifically asks people not to use these maps specifically asks people not to use these maps USDA’s website several significant changes "What's New | USDA Plant Hardiness Zone Map" USDA Agricultural Research website knowing your Zone USDA: Hardiness Zone Maps USDA website