Thomas Ogren holds a Master of Science in Agriculture, with an emphasis on plant flowering systems and the connections between landscape plant materials and allergy. Tom started researching allergy-free gardening because his wife, his mother and his sisters all suffered from hay fever and asthma. He is the creator of the Ogren Plant Allergy Scale (OPALS^TM), the first plant-allergy ranking system in existence, which is being used by the USDA to develop allergy rankings for all major U.S. urban areas. For twelve years, Tom taught landscape gardening in a California Youth Authority maximum-security prison, and he has also worked with the University of California Youth Cooperative Extension to establish community gardens in the Los Angeles inner city. He has been the co-owner of a family nursery in the Midwest, where he hosted the popular radio call-in gardening show, "Tom Ogren's Wild World of Plants." He writes for Garden Design, California Landscaping, The New Scientist, Alternative Medicine, American Rose, Conscious Choice, Awareness, Environmental Building News and Pacific Coast Nurseryman. He lives with his family in San Luis Obispo, California.