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.

Research

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.

Roots

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 Rose. Northern Accents™ Lena 2008 Pink and white Hardy shrub with frilly five-petal flowers 3-4'
Northern Accents Ole Rose. Northern Accents™ Ole 2008 Ivory to pale pink Hardy shrub rose with double petals 3-4'
Northern Accents Sven Rose. Northern Accents™ Sven 2008 Pink to pale violet Hardy shrub rose with fragrant double flowers 3-4'
Northern Accents Sigrid Rose. Northern Accent™ Sigrid 2012 Deep pink to red Hardy shrub rose with fragrant flowers 3-4'
'Summer Waltz' Rose. Summer Waltz 2012 Medium pink Double cupped frilly 3.5 inch blooms with light fragrance 4-4.5'
'Prairie Fire' Rose. Prairie Fire 1959 Bright red Shrub, single blooms 4-6'
'Viking Queen' Rose. 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.

Know to Grow

Northern Accents™ polyanthas (meaning "many flowered") die back to the crown in winter, and by June will have regrown to two feet tall, with a profusion of buds and blossoms. They bloom all season, and need no special winter care. No special pruning is required. Deadwood should be removed in early spring. Cultivated roses perform best when fertilized with a balanced formulation in early spring after thaw, one at the end of the first spring bloom, and a final fertilization in mid-late July.