Gardening Articles: Flowers :: Roses
The Rugged Roses (page 3 of 3)
by Thomas Christopher
Laissez-Faire Rose Culture
My own experience suggests that a moderate dressing of aged manure in late autumn is all the feeding rugosa roses need. Verrier prefers horse manure. As their adaptation to the Maine coast suggests, rugosas prefer sandy, well-drained soils, though I have grown them most successfully in the compacted rubble at the edge of a parking lot. I dug big planting holes, though, and mixed large amounts of compost into the backfill. Verrier notes that even a heavy clay soil won't seriously harm rugosas. It only slows the development of their full beauty.
Rugosa roses are troubled by few insects than Japanese beetles, and beetle damage, though temporarily disfiguring, isn't serious. Rose stem girdler beetles and mossy rose gall wasps occasionally attack rugosas -- the symptom is a sudden wilting of a healthy cane. The treatment is simple: prune affected branches back to below the insect's point of attack, and destroy the prunings. A healthy shrub will recover quickly. Don't spray rugosas with pesticides. Most will burn the leaves, causing more damage than the pest.
Wild rugosas and some of the more primitive cultivars such as rubra have a tendency to sucker, and the gardener must remove these new shoots or neighboring plantings will be overrun. Other than that, the only pruning required is the removal of winter-damaged canes (and these are few, as these roses are cold-hardy to -40 degrees F.) and perhaps a minor thinning and shaping in early spring to encourage compact growth. These are roses that can take care of themselves -- so step back and enjoy.
Where They'll Grow
Rugosas give new meaning to the word hardiness. Wild specimens overwinter successfully in zone 2. And rugosas tolerate not only extreme cold but also heat, drought and intense sunlight. Rugosas are exceptional in this respect, and so are suited to many regions where traditional garden roses do not flourish.
A study of shrub roses conducted by Edward R. Hasselkus and Jeffrey Epping from 1987 through 1988 in botanical gardens and arboreta throughout the upper Midwest (Wisconsin, Minnesota, Illinois and Ohio) found the rugosas to be clearly the best adapted to that climate. Not all rugosas proved equal: Sir Thomas Lipton, for example, died back to the snow line in winter and got black spot in the summer. But many cultivars like 'Fru Dagmar Hastrup', 'Belle Poitevine' and 'Blanc Double de Coubert' came through with high marks.
Rugosas are a good bet throughout the Rocky Mountain states and the prairie provinces of Canada, though they do require irrigation in dry climates. Unfortunately, however, they are not for every region. Clair Martin, rosarian at The Huntington Library and Botanical Gardens, San Marino, California, notes that rugosas are outstandingly disease resistant in his garden, but are not as vigorous as in the North. A rose that reaches six to seven feet in Toronto might make 18 inches in Los Angeles. However many hybrids are more tolerant, though Martin adds that all prefer afternoon shade, especially in hotter, inland valleys.
For southern Californians, the best of the rugosas are two hybrids created by Ralph Moore in Visalia, California. These are: 'Linda Campbell' (bears bright crimson blossoms in large clusters) and 'Topaz Jewel' (a semi-double, pale yellow rose that does not perform well in northern regions).
In the East, the southern limit of the rugosa roses range is normally zone 7, though they grow reasonably well at the higher elevations of zone 8. William Welch, a horticultural extension specialist at Texas A&M University and a leading authority on roses for the South, warns that rugosas do not perform well in truly hot and humid areas such as the Gulf Coast. On the plain immediately inland, rugosas may grow for a while but are generally short-lived. Welch notes that alkaline soils cause chlorosis in rugosas, yellowing their normally deep green foliage. There are limits, apparently, to even rugosa hardiness.