Species In Our
This dwarf to semidwarf species is commonly known as the Alpine Rose. It is native to the Swiss Alps and the Pyrenees and has been in cultivation in Britain since 1740. It is hardy to -15°F and is rated by Greer at 3/4/3, for flowers, plant & foliage, and performance. The leaves are well described by its name, which means rust-colored. This is a very neat, dense, and compact plant with healthy, deep green leaves, the tops of which are glossy green with dense, rusty brown scales on their undersides and which in some varieties have wavy edges.
This is a very attractive addition to our species gardens, since it is one of the latest dwarf plants to bloom. The flowers are red crimson to pink and appear in July. These flowers, three quarters of an inch long, are tubular, with spreading lobes and are held in trusses of six to eight. These plants will take sun but need perfect drainage. This species is desirable because late spring frosts will not affect its flowers. There are also white forms of R. ferrugineum which supposedly are harder to grow than the pinks, but should be worth trying, according to Cox's Guide to Choosing Rhododendrons.
One problem is that in the eastern United States we may have excessive summer heat for R. ferrugineum to survive. Possibly, areas close to water might be cool enough to sustain this plant. It has been suggested that hybrids between this species and R. hirsutum often occur where they meet in their natural European habitat. Supposedly, these hybrids are easier to grow. Both species grow also on calcareous soil and are considered slow growing.
Bulgin's book on hybrids, Rhododendron Hybrids: A Compendium by Parent, lists no commercial hybrid with R. ferrugineum as a parent. However, the old hybrid 'Laetevirens' (also known as 'Wilsoni') is commonly listed as a hybrid of minus x ferrugineum. There is evidence that the actual parentage may be concinnum x ferrugineum. Couldn't we use this desirable species with beautiful leaves, a late bloomer, as a parent of a new hybrid?
Frank Brako, Acton MA