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March 2012

Dr. Michael Dirr, Biography

Michael A. Dirr, Ph.D

World Renowned Plant Breeder
Hybridizer of Endless Summer® Collection Hydrangeas

Dr. Michael A. Dirrʼs influence in horticulture is far reaching. From landscape and nursery industry professionals to the home gardener, his teaching and research have impacted the way we interact with woody landscape plants.

Landscape Management magazine recognized Dr. Dirr as the number one academic contributor to the landscape industry. Dirr has published more than 300 scientific and popular publications and has authored 12 books. His book, Manual of Woody Landscape Plants: Their Identification, Ornamental Characteristics, Culture and Propagation and Uses is one of the most widely adopted reference text in Horticulture and Landscape Architecture education. It has sold over 500,000 copies. From 1981 to 2007 Dr. Dirr fostered the University of Georgia Plant Introduction program, a program widely emulated by other universities. His program has contributed more than 100 new plants to the industry, with 13 patents.

From the very beginning, Dr. Dirr has been instrumental to the success of the Endless Summer® Collection. In September of 1998, he was visiting Bailey Nurseries in St. Paul, MN. While walking through the test facility Dr. Dirr saw a unique H. macrophylla, a variety he would later learn could flower on both old and new growth. Bailey Nurseries patented the plant and trademarked a name scribbled in Dr. Dirrʼs notes – ʻEndless Summer.ʼ At the end of the 2007 growing season, more than 7 million Endless Summer® The Original were sold. The plant is now available in Canada, Europe, Australia and Asia.

In 2005, Bailey Nurseries introduced Endless Summer® Blushing Bride, a pure white, reblooming H. macrophylla bred by Dr. Dirrʼs program. In 2009, Endless Summer® Twist-n-Shout™, a reblooming lacecap H. macrophylla from Dirrʼs breeding program hit the market. For 2011, Dirr's first pink Annabelle hydrangea in, Endless Summer® Bella Anna™ Collection will became available for hydrangea lovers everywhere.

As a tribute to his many contributions to the plant world, the Department of Horticulture at the University of Georgia established the Michael A. Dirr Endowed Professorship for Woody Plant Instruction and Introduction. The endowment will insure that future faculty members will embody the commitment to teaching, research and woody plant introduction exemplified by Dr. Dirr.

Dirr earned his Bachelor of Science and Masters of Science degrees in Horticulture from The Ohio State University and a Ph.D in Plant Physiology from the University of Massachusetts. Upon graduation from the University of Massachusetts, Dirr was an Associate Professor of Ornamental Horticulture at the University of Illinois, Urbana, where he continued to work until 1978. He then became a Mercer Fellow at the Arnold Arboretum of Harvard University through 1979. In 1979, he became the Director of the University of Georgia Botanical Garden. In 1981, he returned to teaching and research at the University of Georgia and was promoted to Professor in 1984.

In October of 2003 Dr. Dirr officially retired from the University of Georgia, but not from research and plant development. He is a founding partner of Plant Introductions, Inc. PII breeds, evaluates and introduces new woody and herbaceous plants for the nursery industry. The company’s new breeding, propagation, production and testing facilities are located in Watkinsville, GA.

Bailey Nurseries is proud to be working with Dr. Dirr in his quest to bring only the most outstanding plants to market. Continue to look for future introductions brought to you by this collaboration of efforts.

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