Dr. Michael A. Dirr’s influence in horticulture is far reaching. He is a prolific author, exceptional hybridizer and acclaimed educator and researcher. Know alternately as the “modern father of woody plants” and the “hydrangea guru”, his contributions to the world of horticulture are unparalleled.
During his time at the University of Georgia, Dirr’s Plant Introduction program has contributed more than 100 new plants to the industry, with 13 patents. The most notable being a series of re-blooming hydrangeas developed in partnership with Bailey Nurseries. Aptly named “Endless Summer®”, they were the first hydrangeas to bloom on both new and old wood allowing for a summer of beautiful flowers.
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. Often referred to as “the bible” by industry professionals, his book, Manual of Woody Landscape Plants, is one of the most widely adopted reference texts in horticulture and landscape architecture education. It has sold over 500,000 copies.
Dirr has received more than 20 awards, among them the highest honors from the American Horticultural Society, Garden Clubs of America, American Nursery & Landscape Association, and the American Society for Horticultural Science. A professorship in his name has been established in at the University of Georgia in recognition of his accomplishments.
To have advance look at the full digital version of Dirr’s Encyclopedia of Trees and Shrubs, send your request to Danielle Marshall - dmarshall@timberpress.com.
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Timber Press is a Portland, Oregon, publisher of books on gardening, ornamental and edible horticulture, garden design, sustainability, natural history and the Pacific Northwest.




