One of the most important considerations to be made in choosing plants for any garden is hardiness zones. The U.S. Department of Agriculture developed and maintains a USDA Plant Hardiness Zone Map that assigns a numerical value and color to every area of the United States. In our catalogs and on our website, we're careful to specify hardiness zones for each plant. But customers have asked us to do more to help them choose the right plants for their zones. On this page we list our bulbs by zone.