Christina Pfeiffer is a horticulture consultant, instructor, and garden writer with over 30 years experience in landscape management and arboriculture. Sustainable and efficient landscape techniques are a special area of her interest and expertise. In addition to being a frequent horticultural speaker, Pfeiffer has taught courses in pruning, arboriculture, and landscape management at Edmonds and South Seattle Community Colleges, and at the University of Washington. She is a contributing writer and member of the Washington Park Arboretum Bulletin editorial board. Christina holds degrees in horticulture from Michigan State and the University of Washington and is an ISA Certified Arborist. She is co-author with Mary Robson of Month-by-Month Gardening in Washington & Oregon.

Mary Robson was a cooperative extension agent with Washington State University in Renton, Washington. She wrote The Practical Gardener column in The Seattle Times. Her weekly WSU Cooperative Extension garden column was featured in other local newspapers including the Tacoma News Tribune and the Everett Herald. Robson provided gardening information on the "Voice of the South Sound" KHHO, 850 AM in Tacoma. She is the co-author of Washington & Oregon Gardener's Guide and Month-by-Month Gardening in Washington & Oregon.