Rugosa roses are a class of nineteenth-century origin. But the potential of using Rosa rugosa as a parent in breeding programs only surfaced a few decades ago. This produced a wealth of plant material that has resulted in one of the larger and more important classes within the shrub rose group.
The result is a rose with exceptional cold tolerance and disease resistance, handsomely wrinkled foliage of the rugosa parents, but with a wider variety of flower form and color and a plant habit that ranges from compact shrubs to vigorous climbers. Rugosas make perhaps the ideal low-maintenance landscape rose. In fact, applying fungicides often results in very severe leaf injury and loss. Rugosa roses can tolerate drier conditions without much reduction in bloom and can be grown in light shade. Add to this their ability to produce an exceptional display of hips in the fall and attractive fall color and you have a rose that most home gardeners welcome.
Two outstanding strains of hybrid rugosa roses are the 'Canadian Explorer' series and the 'Parkland' series. Both of these are products of Canadian rose breeding programs. The 'Explorer' roses were bred in Ottawa, Ontario and named after famous Canadian explorers. The 'Parkland' roses came from Morden Station in Morden, Manitoba, Canada. 'Parkland' roses differ somewhat from 'Explorer' roses in that the 'Parklands' may freeze to the snow line or to the ground. If they are on their own root, they will regrow and flower very well. This freezing back tends to make 'Parklands' a smaller-statured plant perfect for the perennial garden or smaller urban garden. There are a number of 'Explorers' that make excellent climbers for northern gardens.
Some key points with 'Explorer' and 'Parkland' roses are: (1) they tend to do better when not fertilized to excess; heavy fertilization prompts lush, soft growth. (2) Because the 'Explorers' have rugosa heritage, they do not like fungicide applications; treatment with fungicides for blackspot will make leaves deteriorate faster. (3) Many of the hybrid rugosas perform better in cooler climates. In areas where it gets very hot, performance tends to decline. There are however a number of varieties that are more heat tolerant. Many rugosas are also tolerant of salt spray, which makes them good candidates for planting in areas where road salt spray is a problem.