There is nothing ordinary about Michael Dirr or his classes – This statement by Faith Peppers of Georgia Extension Service says everything about Dr. Michael Dirr.

Michael A. Dirr is a legendary horticulturist and was a professor of horticulture at the University of Georgia. His lifelong passion for horticulture has positively influenced a generation of students, gardeners, nursery-men, and professional horticulturists. He is the author of over ten books on Woody Landcape Plants and Trees and has published more than 300 scientific and popular publications.

Dr. Dirr is also popularly known as the Hydrangea Guru for his exceptionally great research on Hydrangeas.

Michael Dirr’s Contributions

Dirr’s Plant Introduction Program has contributed over 50 new plant introductions to the Green Industry. He developed Lady in Red, a variety of Hydrangea macrophylla. It is the first patented release from the University of Georgia’s "Continued Adventures in Plant Improvement in the Department of Horticulture and Center for Applied Nursery Research" program, headed by Dr. Dirr.

Dr. Dirr wrote a number of books on Horticulture with special focus on woody landcape plants and trees. Some of the most popular works of Dirr are as follows-

• Hardy Trees and Shrubs: An Illustrated Encyclopedia: According to Library Journal, this book is a first-class source on the very best garden trees and shrubs. Excellent color photos accompany the well-written plant descriptions, which point out both the positive and negative attributes of each plant, including physical features, hardiness, disease resistance, and growth preferences. A multitude of cross-referenced indexes will help readers find the right plant for each location and desired effect.
• Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture, Propagation and Uses: This classic manual offers thorough information on the woody trees and shrubs used in landscaping. Aside from each plant’s physical description, there’s also an elaboration of hardiness, growth rate, culture, diseases and insects, landscape value, cultivars, and propagation.
• Hydrangeas for American Gardens: Publishers Weekly says, "his passion for hydrangeas "knows no bounds" is clear from this enthusiastic combination of rigorous science, concise description and seasoned advice. The first chapter, "Characteristics, Taxonomy and Nomenclature," is the most academically oriented but brief and readable enough for the home gardener. Ten well-organized and liberally illustrated chapters follow, each devoted to a single species and its subspecies, ranging from the familiar and hugely popular H.macrophylla and H. paniculata, to relative rarities boasting flower buds that remind Dirr of "purple-brown cauliflowers" and are sometimes "quite large and Martian." Chapters on care and culture, propagation, pests and diseases, potpourri, and breeding offer a wealth of practical insights equally valuable to the casual green thumb and the professional horticulturist".
• Trees and Shrubs for Warm Climates: An Illustrated Encyclopedia: With more than 1400 beautiful photographs, personal observations of over 400 species, and hundreds more cultivars and varieties of trees, shrubs, and vines that grow in the temperate zones of the Southeast. Intended as a companion volume to Dirr’s Hardy Trees and Shrubs: An Illustrated Encyclopedia, this new book will be useful to landscapers, garden designers, horticulturalists, and home gardeners located in the South, as well as the West Coast through British Columbia. Dirr also includes a section on cold-hardy palms that will survive in growing zones 7-11. What sets this book apart from many other botanical encyclopedias is the author’s personal writing style, which breathes life into the text. Each plant is described in detail, showing flower, fruit, bark, fall color, and any other distinguishing characteristics.
• Trees and Shrubs for Warm Climates: An Illustrated Encyclopedia: With more than 1400 beautiful photographs, personal observations of over 400 species, and hundreds more cultivars and varieties of trees, shrubs, and vines that grow in the temperate zones of the Southeast. Intended as a companion volume to Dirr’s Hardy Trees and Shrubs: An Illustrated Encyclopedia, this new book will be useful to landscapers, garden designers, horticulturalists, and home gardeners located in the South, as well as the West Coast through British Columbia. Dirr also includes a section on cold-hardy palms that will survive in growing zones 7-11. What sets this book apart from many other botanical encyclopedias is the author’s personal writing style, which breathes life into the text. Each plant is described in detail, showing flower, fruit, bark, fall color, and any other distinguishing characteristics.
• Great Flowering Landscape Shrubs: With stunning color photos throughout, this gardening guide describes more than 50 types of the best flowering shrubs and details their use in home landscaping. Shrubs are arranged by genus, separated into deciduous flowering and notable evergreen shrubs, and listed with the common name; size and shape; foliage color, shape, and texture; flower and fruit (if any); soil, nutrient, and light needs; pruning needs for maximum growth and/or flower; and USDA Hardiness Zones. Details of specific species, cultivars, and varieties that lead to exceptional size, color, flower, hardiness, and durability are also included.
• The Reference Manual of Woody Plant Propagation: From Seed to Tissue Culture: According to John Szabo, a reader, "Dirr has done all the research and you reap all the rewards. His conclusions are backed up by many scientific studies by various individuals and groups."

Achievements and Awards won by Michael Dirr

Michael Dirr has received more than 20 awards for highest teaching and research from the University of Georgia, American Society of Horticultural Science, American Horticultural Society, American Nursery & Landscape Association, Massachusetts Horticultural Society, Southern Nursery Association, and Garden Club of America. Dr. Dirr has been recognized for his outstanding contributions to horticulture, both in and out of the classroom.

• American Horticultural Society’s Teaching Award
• Arthur Hoyt Scott Garden and Horticultural Award
• ASHS Undergraduate Educator Award
• Medal of Honor from the Garden Clubs of America
• Southern Nurseryman’s Association (SNA) Slater Wight Memorial Award
• Jackson Dawson Medal for Outstanding Contribution to Plant Propagation.
• Medal of Honor from The Garden Club of America.