The showy ‘Summer Waltz’ rose, released in 2012, is covered with double-cupped frilly pink flowers, blooming through- out the season until frost. The lightly fragrant flowers fade to light pink as they age. As with most repeat blooming roses, there is partial die back of the crown to winter injury. It is tolerant of black spot fungus—plants may get a little, but it doesn’t impact plant appearance or performance. ‘Summer Waltz’ is available only at the Minnesota Landscape Arboretum Auxilary Plant Sale each May.
Four super-hardy shrub roses—known as Northern Accents™ ‘Sven,’ ‘Ole,’ ‘Lena,’ and ‘Sigrid’—grow to more than three feet tall, covered in a profusion of clustered blooms all season. In Grand Rapids they survived a winter with a low temperature of -47°F. With consistent snow cover, they need no special winter care. They are resilient and environmentally gentle as well. At trials near Dallas, Texas, the U of M polyanthas grow to eight-foot shrubs with no special inputs other than water and mulch at planting.
Black spot fungus has challenged rose gardeners for centuries. Using black spot isolates collected from across eastern North America, University scientists can characterize the molecular diversity of the fungus. Rose genotypes are inoculated with black spot isolates to determine the race diversity of the isolates. Breeders then identify black spot resistance genes in rose germplasm and begin the process of incorporating those genes into cold-hardy shrub roses.
Roses were some of the earliest woody landscape plant cultivars released from the University, as a sideline of the chrysanthemum breeding project in the 1940s. The first directed breeding work on woody landscape plants can be dated to 1942 when Dr. Louis E. Longley, who started the chrysanthemum breeding project, began making some crabapple and rose crosses.
Longley is credited with releasing four roses, ‘Pink Rocket,’ ‘Red Rocket,’ ‘L.E. Longley,’ and ‘White Dawn,’ in 1949, and with developing the ‘Radiant’ crabapple. His assistant, Robert A. Phillips, continued to make rose hybridizations after Longley’s retirement in 1949. Two additional rose cultivars, ‘Prairie Fire’ and ‘Viking Queen,’ are attributed to Phillips and are still available.
U of M Rose (Rosa) Varieties
|Image||Variety||Year||Flower Color||Features||Plant Size|
|Northern Accents™ Lena||2008||Pink and white||Hardy shrub with frilly five-petal flowers||3-4'|
|Northern Accents™ Ole||2008||Ivory to pale pink||Hardy shrub rose with double petals||3-4'|
|Northern Accents™ Sven||2008||Pink to pale violet||Hardy shrub rose with fragrant double flowers||3-4'|
|Northern Accent™ Sigrid||2012||Deep pink to red||Hardy shrub rose with fragrant flowers||3-4'|
|Summer Waltz||2012||Medium pink||Double cupped frilly 3.5 inch blooms with light fragrance||4-4.5'|
|Prairie Fire||1959||Bright red||Shrub, single blooms||4-6'|
|Viking Queen||1963||Pink||Large, fragrant climber with double blossoms and glossy foliage||8-10'|
Northern Accents™ is a trademark of the University of Minnesota.