Cultivar development of shrub roses at the University of Minnesota horticultural Research Center

A shrub rose hybridization program with the objective of developing USDA Zone 4 hardy, black spot tolerant, attractive, repeat blooming cultivars was initiated in 1990. Parental germplasm was selected from several taxa, including species roses, Old Garden roses, Shrub roses, Miniature roses, and Polyantha roses. Species roses and hardy cultivars among the Albas and Gallicas are sources of black spot tolerance. Shrub roses, especially those developed by the Agriculture and Agri-Food Canada program and those developed at Iowa State University, combine repeat bloom and cold hardiness. Miniature and Polyantha roses provide a combination of repeat bloom and small stature. Recurrent selection is used and superior individuals from each generation are evaluated for potential as cultivars and/or as parents for subsequent hybridization. Currently, 220 adVanced selection hybrids are being used in the breeding program. Eleven Shrub rose selections and four Polyantha selections are in regional and national trials. Three Polyantha cultivars will be released in 2007.