Michael Dirr, Ph.D. is a horticulturist and a currently retired, professor emeritus of horticulture at the University of Georgia. He is an expert on woody plants. Dr. Dirr has introduced over 200 plants to cultivation, with 29 being patented while at the University. He has written countless articles, along with 8 books – the best known being his Manual of Woody Landscape Plants, which is the most widely used text and reference book in the United States. He has also started, not one, but two breeding companies with his partners, Jeff Beasley and Mark Griffin. The first was sold to Bailey Nursery, MN in 2015. The second is his lastest venture.

Mark Griffith started Griffith Propagation Nursery over 40 years past when he enrolled in Horticulture classes at UGA. Mark always believed that new introductions, backed by credible research data, would allow a head start on the competition. This allowed him to be among the first to offer the newest of the new. Mark's enthusiasm for improved plants led to Plant Introductions, Inc, a plant breeding company.

Jeff Beasley is a second-generation nurseryman and plant breeder. He learned the trade from his father, George Beasley in their small family nursery. In 1980, Jeff and his wife, Lisa took over the small family business and grew and operated Transplant Nursery for 34 years, when they successfully transitioned the business to their daughter and son-in-law, Camilla and Gatlin Correia.

Mark Griffeth, Jeff Beasley, and Mike Dirr, the first iteration of PII developed over 60 patented plants, including the Endless Summer collection, the most recent being Pop Star(r). After selling the company in 2015 to Bailey with a five-year non-compete, Mark, Jeff, and Mike opted to start anew in 2020. To date, the new PII (Premier Introductions, Inc.) has secured seven patents, with more in the pipeline.