Michael Dirr at the National Arboretum

by Marsha Goldberg, Fairfax Master Gardener
Staff members and volunteers at the National Arboretum had the chance to hear Michael Dirr speak about his current research and breeding programs when he visited recently.

Michael Dirr

Michael Dirr

In 2007, Dirr started a company, Plant Introductions, Inc., which develops breeding programs to address consumer needs and improve the performance of ornamental garden plants. Dirr explained that, at the company’s onset, he did not have the marketing expertise to make the project financially viable so he collaborated with Bailey Nurseries in Minnesota, a wholesale grower, to bring his products to market. PII is now a subsidiary of Bailey and serves as their in-house breeding division. Dirr was exploring the possibility of a further collaboration with the Arboretum.

Dirr pointed out that the shrubs people purchase the most frequently are boxwood, viburnum, and hydrangeas, so much of his work is focused on those. He discussed his efforts to develop new cultivars of distylium, “…the most beautiful plant you never heard of.” Distylium are underused in American gardens but are an extremely attractive alternative to plants such a cherry laurel, junipers, hollies, and boxwood, which are subject to ruinous diseases, such as boxwood blight. Members of the witch hazel family, Hamamelis, dystylium are compact, evergreen, disease- and insect-resistant shrubs for full sun t