ASHS 2015 Annual Conference

More than 1,000 species have been described in the genus Rhododendron, Ericaceae (heath family). While the genus has rendered some of the most beautiful flowering shrubs available for use in the landscape, relatively few species from the genus are winter hardy in USDA Zone 4 landscapes (average annual minimum temperature -30 to -20°F). The deciduous azaleas (Rhododendron subg. Hymenanthes sec. Pentanthera), with 15 species native to North America, are the most cold hardy of the Rhododendron species. Since 1957, the University of Minnesota Woody Landscape Plant Breeding and Genetics program has been actively engaged in a deciduous azalea breeding effort, utilizing cold-hardy species and cultivars to develop reliably cold hardy cultivars with a wide range of flower colors.  Over the years, the program has released 15 cultivars in the Lights Series of deciduous azaleas. Herein we describe the two newest Lights Series deciduous azalea cultivars to be released by the project; ‘UMNAZ 493’ PPAF First Editions® Electric Lights™ Double Pink Azalea and ‘UMNAZ 502’ PPAF First Editions® Electric Lights™ Red Azalea. ‘UMNAZ 493’, selected in 1994, is a hose-in-hose double-flowered type with light pink flowers. ‘UMNAZ 502’, selected in 1995, is the first red-flowered cultivar released by the program. Based on field observations and laboratory cold-hardiness tests, ‘UMNAZ 493’ and ‘UMNAZ 502’ are rated winter hardy to USDA Zone 4a (-25 to -30°F).