Michael A. Dirr, Ph. D., is a horticulturist and a professor of horticulture at the University of Georgia. He has published over 300 scientific and popular publications and has written seven books. Dirr earned his Bachelor of Science and Master of Science in Plant Physiology from Ohio State University. He received his Ph. D in Plant Physiology from the University of Massachusetts Amherst, in 1972. After his doctorate, Dirr was an assistant professor of Ornamental Horticulture at the University of Illinois, Urbana, until 1978. He then became a Mercer Fellow at the Arnold Arboretum of Harvard University. In 1979, he became the director of the University of Georgia Botanical Garden. He returned to teach at the school in 1981 and became a professor in 1984. He retired in 2023 and now focuses on research and new plant development.