This session will cover how the United States Department of Agriculture (USDA) Plant Hardiness Zones came to be, what they mean to gardeners and why they are still in use almost a hundred years after the first hardiness maps were developed. The presentation will include a review of early colorful, hand-drawn maps from the archives of the Arnold Arboretum at Harvard University in Massachusetts, the latest computer-generated maps from the USDA and commentary on the recent zone revisions.

Tom Packer is an Extension Master Gardener volunteer from Wake County, North Carolina and Chair of its management team and community gardening helpline. He serves on the North Carolina Cooperative Extension Agricultural Programs Foundation Board. Tom also is President of the 84-year-old Gardeners of Wake County club, has authored many articles on gardening and horticultural topics, and is a long-time backyard farmer in northern California and North Carolina. He earned his undergraduate and law degrees from the University of California.