Rhododendrons for Foliage Effect
Kallista, Victoria, Australia
Reprinted from Australian Rhododendron Society Journal
One of the most fascinating phases of the rhododendron season comes after the blooms have finished and when the glorious new growth unfurls, provided, of course, we have chosen our plants carefully.
The genus rhododendron covers an enormous variety of plants from tiny prostrate shrublets to majestic trees which on the whole are slow growing and long lived, and the genus contains many species with superb foliage. When one considers that the flowering season of any individual rhododendron (excluding vireyas) is generally restricted to a few weeks in the year, it always seems puzzling that more consideration is not given to the general appearance of the rhododendrons we grow in our gardens from the point of view of the plants as foliage plants, as after all we look at the foliage throughout the whole year. The average gardener seems only to acquire rhododendrons as flowering plants, and gives no thought whatsoever to the foliage of the plants which he, or she, must look at for all the year around, and this is reflected in so many nurseries stocking rhododendrons which look deadly dull when the plants are not in flower - hence the scarcity of the much more attractive species which in so many instances are just as attractive out of flower as in flower. Some are such beautiful foliage plants that the flowers must be of secondary consideration, and although some species take many years to bloom, this is of little consequence as the plants can be enjoyed the whole year around. There are some species, of course, with delightful foliage which will also flower at a comparatively early age. I can recall, with much pleasure, the fascination which plant nurseries held for me when we moved up to the Dandenongs some seventeen years ago. In those days there was a large range of captivating foliaged species available, but unfortunately today the situation is much changed. Surely the lack of publicity must bear some of the blame, after all nurseries will stock what the public will purchase, but so many gardeners seem quite unaware of the treasures that they could grow, both in the suburban and hills areas.
Photo by Dr. Herbert Spady
Everyone who has suitable conditions should grow some of the big-leafed species with beautiful indumentum, in the Grandia and Falconera subsections - little does it matter that they take many years to flower. In many of the species in these subsections the new foliage stands up like cockades of white kid enhanced by red bracts and look as lovely as the flowers they will ultimately bear. Of course these species thrive best in woodland conditions in the cooler areas where they can reach their full potential. In my own rather new garden, as I do not have any good shade trees yet, I have to grow these large leafed beauties in a shade house, and even during last summer's devastating drought they continued to thrive and give much pleasure - just to feel the thick tawny indumentum on R. falconeri and its ssp. eximium is a delight. Some of the large leafed species will flower at less than ten years old including R. grande, rex, rex ssp. fictolacteum and magnificum, and also that wonderful hybrid R. 'Elsae'. All these have large trusses with thick fleshy bells. It is a pity really, that in the new Cullen and Chamberlain classification of rhododendrons many former species have only been given subspecies status, or worse still sunk into synonymity. But I suppose that one should keep abreast of the world scene.
Photo by Dr. Herbert Spady
However, for those without ideal conditions for the Grandia and Falconera species, look at species in the Arborea and Pontica subsections. Many of these plants have beautiful plastered silver or woolly tawny to white indumentum on the undersides of the leaves which look lovely when ruffled by the wind, and lovelier when the new growth unfurls. As most of these are quite sun hardy, they should be more widely grown, and they do grow well in suburban areas, if suitably sited and cared for.
Everyone knows R. yakushimanum, and this plant with lovely thick indumentum is widely grown, so why not some of its relatives? Another wonderful species also in the Pontica subsection is R. smirnowii, with its woolly white indumentum, and lovely pink flowers. Then there is the species which used to go under the name of R. metternichii, but now unfortunately it has been classified as R. japonicum var. japonicum, and another interesting one is the narrow leafed former R. makinoi, now R. yakushimanum ssp. makinoi (but so different to R. yakushimanum. Don't forget the arboreums, they come with all sorts of indumentum, silver, and varying shades of bright tan and brown, and the beautiful flowers too come in a great variety of colours from pure white to shades of pink, rose red to the deepest red, whilst its close relative R. niveum is a most unusual shade of violet. Most arboreums begin their flowering careers before too many years pass and want a fairly open position to show off their best. They too can make fine lawn specimens.
One of the most striking of all rhododendrons, from a foliage point of view, is the charming R. campanulatum ssp. aeruginosum, the new foliage being a bright metallic blue, which always stops visitors in their stride when they come around a corner in my garden, and in addition to this almost incredible colour the leaves are also blessed with lovely indumentum. This is a very slow growing plant, my plant is about sixteen years old, and is only about twenty inches high and twenty inches across, but this is not a small leafed variety. As it is difficult to propagate which is done by grafting, it has never been plentiful, and it is a pity that some experienced growers do not take up the challenge and make efforts to widen its distribution. This species rarely flowers, but apparently this is not a disadvantage as the flowers are said to be "nasty!" Another very lovely species that used to be included in the Campanulatum series, but is now in the Subsection Lanata, is R. tsariense. This is one of my favourite species, fairly small leafed, with beautiful cinnamon indumentum, and elegant new growth. I imported this about five years ago, and unfortunately I lost the imported plant, but had propagated it. I have not seen it in flower, but it is supposed to be lovely in bloom. It is a most distinctive and desirable plant.
Photo by Dr. Herbert Spady
Species in the Neriiflora, Fulva and Taliensia subsections also have beautiful foliage with attractive indumentum and some also have most interesting leaf shapes, such as R. roxieanum, particularly in the form oreonastes, which has been likened to a porcupine (a slight exaggeration, I feel). Some of the most widely acclaimed of all foliage plants are found in these three subsections. One need only look at species such as R. mallotum, bureavii and elegantulum to appreciate the fascination of these plants, and there are many others, but they, perhaps, do not quite rival these.
Photo by Felice Blake
Then there is the well known R. griersonianum which has passed on some of its good characteristics to its children such as R. 'May Day' and R. 'Tally Ho' - plants for everyone, and retaining the parental indumentum.
Other rhododendrons have delightful glaucous foliage and rounded leaves as seen in R. orbiculare in the Fortunea subsection and the well known and widely grown R. williamsianum in the Williamsiana subsection, the latter also sporting bronzy new foliage. R. williamsianum has, in particular, passed on many of its better attributes to its many and varied progeny, a number of which have found their places in our gardens, and a collection of these hybrids can make a varied and interesting spectacle.
For those who like graceful willowy looking plants, many of those species found in the Triflora subsection are attractive plants all the year around, apart from their airy-fairy flowers in a variety of colours. R. lutescens is one of my favourites with its entrancing primrose flowers early in the season, followed by its graceful bronzy new leaves, and who could overlook the superlative R. augustinii in its better blue forms - an augustinii walk can be an enticing addition to any garden, even with just six or eight plants and a little imagination with well chosen companion planting.
Photo by Dr. Herbert Spady
Then there are the elegant cinnabarinums, enchantingly different in flower, both species and hybrids, mostly followed by glaucous new foliage, intensely blue in some such as the L. & S. Copper form of R. concatenans (which we must now call R. cinnabarinum ssp. xanthocodon Concatenans Group), and the hybrid R. 'Oreocinn'. Even a small group of Cinnabarinums would add a touch of style and grace to the garden.
Among the more recent introductions is R. pachysanthum from Taiwan, formerly in the Barbatum series but now classified into subsection Maculifera. This is an outstanding foliage plant, the new growth is covered with a white fur which persists for quite a long time, and makes a striking contrast to its companions.
To turn to some of the smaller species which are notable for foliage, the most outstanding must be R. lepidostylum in subsection Lepidostyla. This species is much more renowned for its foliage than for its flowers, with its new blue leaves fringed with hairs, and these do stay blue for quite some time; others in this subsection also have bluish growth, but not nearly so intense in colour. When one comes to the dwarfer rhododendrons the variety is really tremendous, from the tiny-leafed R. telmateium and blue leafed R. fastigiatum in the Lapponica subsection to the glaucous backed leaves in the species in the Campylogyna and Glauca subsections. Quite a number of the little species, particularly in subsection Lapponica, turn very bronzy in winter, more so if you are in an area subject to frosts. I find that I get a lot more winter colour in my present garden at Kallista which is a very open garden, than in my former garden at Mt. Dandenong which had a superabundant collection of Eucalyptus regnans (mountain ash). I also find in my open garden, which is at a much lower level (only about 1300 ft. as against 1850 ft.) that many rhododendrons flower at a smaller size and stay more compact in growth.
One must not overlook deciduous azaleas, both species and hybrids as marvelous additions to the autumn colour in our gardens. Apart from the various Ghent, Mollis, Knap Hill, IIam and Exbury hybrids, don't forget some of the many deciduous species. One particularly good one, is the recently introduced R. kiyosumense from Mt. Kiyosumi in Japan, one of those architecturally interesting plants which has brilliant autumn foliage lasting for many weeks.
Of course, I have not mentioned all those rhododendrons that one could consider as foliage plants, there are many more, so it is up to the interested reader to seek out sources of supply, whether it be from nurseries, private collections, or from seed distributions, or if he is really keen he could always try his hand at importing his heart's desire!