Rest a While in Descanso Rosarium

Gardens are luxury items. To properly care for a garden, you need either leisure time or the means to hire someone to look after it for you. Some people see their garden as nothing more than work and water bills, paving over lawns and flower beds, utilizing the space for a shuffleboard court or sundeck.
In an era of shrinking budgets and vanished luxuries, the construction of an international rosarium at the Descanso Gardens in La Canada Flintridge is that much more remarkable. More than $1 million was spent to create a rose garden that, once it has grown to maturity, will be a horticultural marvel. Already it is a learning experience second to none.
“We wanted the rosarium to be user friendly, a place where people could spend a day learning about roses,” explained Steve Cohan, Descanso Gardens director. “In a typical arboretum, plants are put on display without context. Visitors learn little more about them than their names and habitats. We had 400 botanical garden professionals here not long ago who acknowledged the uniqueness of our effort.”
The Descanso rosarium is a model of what a public garden should be. It’s a place you can appreciate on a number of levels, whether your interest is botany, history, ecology, backyard gardening, a place to take the kids or, per chance, contemplation of beauty for its own sake.
Many of the planted areas are devoted to roses native to or hybridized in particular countries. I learned that floribunda roses – the kind favored by landscapers because of their heavy blooming and disease resistance – were originally hybridized in Denmark, the result of a breeding program for cold tolerance. Hybrid teas, still the most popular garden roses, first appeared in France 130 years ago. Yellow and orange roses can be traced back to Persia.
California takes credit for developing two major categories of roses: grandifloras, hybridized by Walter Lammerts, designer of the original Descanso rose garden in the 1950s, and miniatures, brought to pre-eminence by Ralph Moore, a rose breeder in Visalia. Miniature roses are ideal for small spaces or for sidewalk edging. As potted plants, they are suitable for balconies and even sunny indoor locations. The variety “Si” has flowers the size of matchheads.
Within the rosarium, there are more than a dozen themed garden areas, including butterfly, herb, Victorian and California Mission gardens. There is a children’s maze composed of African boxwood and a white-flower garden. Yet another garden contains several hundred varieties of irises. Roses will form the centerpiece or adorn the pergolas crossing the paths of each themed garden.
Wherever you look, ground covers and perennials have been planted as companions to the roses. Among these, I found Prunella and Veronica species especially intriguing. Anyone looking for landscaping ideas will benfit from a study of the plant combinations on display.
Mary Brosius, rosarium curator, recommends Rosa Mutabillis, a low- growing, lightly thorned plant with pink and yellow roses, for landscaping. She also is partial to “Dapple Dawn,” a David Austin variety.
Both Cohan and Brosius believe that growing roses successfully is no big deal. The most important condition for growth is full sun from every direction. Roses are not finicky about soil and do not demand an overabundance of fertilizer. Species roses require fertilization twice a year, and hybrids three times – April, June and September.
I asked Cohan about planting with peat moss, since I had long heard this practice recommended for roses. He shook his head. “When planting, all you need to use is compost,” he said, “but don’t let it exceed one-third of the backfill if you want your plants to adapt to your garden soil. Clay soils are not a problem – it just means you don’t have to water that much – and neither is moderate alkalinity. The soil pH here is 7.5, and we see no signs of mineral deficiency in our roses.”
The phenomenal growth of the Descanso roses, since they were planted in late March, is a testimonial to drip irrigation. The root zone of each plant is kept steadily moist with the help of a single emitter.

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