Radiant rhododendron show

Press, 30 October 1981, Page 11

Radiant rhododendron show

Gardener’s' ©diary

Derrick Rooney

The rhododendron is the queen of flowering shrubs, as all gardeners know and, no doubt, will reaffirm when they visit the first Christchurch rhododendron show in the Horticultural Hall this week-end; there is probably no other genus of cultivated plants with the range of floral beauty, size, and shape found in the 600odd species of rhododendron. But when I visit the rhododendron show I will be looking for more than flowers; I will be looking at foliage, too.

'The flowers are only part of the story with rhododendrons: they are there for only a' few weeks of the year, whereas the leaves are there all the time — at least, for a couple of years, which is the average span of a rhododendron leaf.

And while the average flowering rhododendron is a pretty dull foliage plant, there are some whose floral beauty is matched or surpassed by ruggedly handsome leafage. To be reminded of this home truth I need look only at the fierycoloured emerging foliage of the williamsianum hybrids, the silvery sheen of Rhododendron argyrophyllum, or the lovely, glaucous Rh. viridescens.

I planted the latter without premeditation; I wanted lepidostylum, but as it was not available viridescens was offered as a more than acceptable substitute.

It is a small shrub, about 30cm high at present, and even in its old age it will not be much more than a metre high. The oval leaves are vivid green and, when young, have a lovely glaucous sheen.

This is one of the rarer rhododendrons, having been found in only one location in south-eastern Tibet, which is now closed to Western collectors. It grows there at altitudes above 3000 metres in a harsh climate, so it should be a tough customer, and to indicate my confidence in it I have, planted it with more exposure than I usually give my rhododendrons. This is one of the last to flower, and the funnel-shaped pale yellow blooms may not appear until December. Even if no flower buds are visible in spring there is no need to despair, because sometimes this species flowers on the young wood in late summer.

Rh. argyrophyllum and Rh. decorum, two foliage favourites, are much larger plants but they, too, will stand a deal of exposure.

Rh. decorum has been used extensively for hybridising and is the progenitor of many well-known offspring, but the parent is as good as any of them — or perhaps it is a case of the’ offspring being nearly as good as the parent. Decorum is a decorous shrub at most times of the year — occasionally in summer the young foliage scorches but any damage is usually hidden fairly quickly by new growth once rain falls. The leaves are handsome — glossy, light green with a silvery sheen when young — and .the flowers are very good, too: large, and well presented clear of the foliage.

This quality, plus precocity (seedlings sometimes flower in their second or third year) transmits readily to the offspring, as does the colour, pale yellow to cream — shades which show up in the garden. Rh. argyrophyllum is much less precocious, and my specimen, planted out five years and now nine or 10

years from seed, produced its first flower this year, carelessly coinciding with a nor’wester which blew it off.

The brief glimpse that I had revealed the colour to be deep pink, almost a cherry colour, whereas the books describe the flowers of this species as “white to pale pink.”

The leaves are very handsome, especially in a breeze which ruffles them so that the undersides are exposed — these are covered with silvery-white fuzz. When the leaves are young both sides have the silvery coating, and in early summer, when the annual growth spurt begins, the bush is very colourful. One of the most elegant of the dwarf rhododendrons is Rh. williamsianum, which is also among the trickier species in Canterbury because it resents the low humidity during our summers.

The advice usually handed out with this expensive plant is to give it full exposure to sun and water it often, but I have seen some miserable specimens in well-watered gardens, and I think the sun makes them scruffy. As I cannot, provide dark glasses for my new young plant (the established one died in last summer's drought) I have given it a sheltered spot in the coolest part of the garden, where it is away to a flying start.

The mature leaves of Rh. williamsianum are roundish-heart-shaped, very smooth, and light apple-green. Young leaves have a coppery.sheen. The plant, when well grown, has great beauty of flower to match its leafage. The bell-shaped blooms are large, warm pink, and well presented. But it is too slow growing to achieve notoriety as a garden shrub, though fortunately it is well able to transmit its virtues to its offspring, so that it has become the daddy (or mummy) of many choice hybrids.

“Humming Bird” and “Temple Belle” are two good ones; another, which is in my garden but not yet flowering, is. “Bow Bells” — it has

pretty rosy-pink flowers and copper-gold young foliage that appears while the flowers are still out, at which stage the shrub exudes charm.

“Jock" is another; there are various forms of this cross with the fiery red Rh. griersonianum, and I like best "Jock Bonny Bells,” which is flowering as I write. This is a sprawly bush, but when the flowers open its sins are forgiven.

I wish I could do better with Rh. oreotrephes, which in leaf is one of the most handsome of all rhododendrons, but I am consoled by the knowledge that .others, too, have difficulty with this species.

It is a choosy shrub which dislikes being moved, and the secret might be to catch it young and put it in its permanent position while it is still small. The snag is finding the right position. My plant is the form with blue-tinted leaves which has been available from several nurseries in recent years and it has looked unhappy since the day I brought it home. I have moved it several times, with callous disregard for its sensitivity, without finding the right spot, and now I have it, finally, in the coolest available place. If it doesn’t pick up its socks this year it will go to the hottest place — the bonfire.

Of course, when autumn comes I may well give it another reprieve, especially if it is showing flower buds, because when it flowers in early summer it is one of the most handsome of shrubs — mauve-pink flowers sit very prettily against the glaucous foliage. In winter the leaves droop and it looks chilled to the bone, but that is just protective camouflage; it is more than hardy enough to stand any winter frost to which the New Zealand climate can subject it.

There are several forms of this species in the country, and recently I acquired a green-leafed one with the promise that it will have the same pretty pinkish flowers but will be easier to “do.” It is a very small plant, though, and will have to be nursed along in the shadehouse for a year or two before it can safely go out in the garden, so it will be a while before it becomes clear whether there was more goodwill than truth in the promise.