JARS v43n4 - Let's Plant Trees

Let's Plant Trees!
Felice Blake
Kallista, Victoria, Australia

Yes, let's plant trees. No, not that sort of tree, not oaks and beeches which, if we have room, we would plant anyway, but rhododendron trees. To begin with, just look at the wonderful variety seen in Rhododendron arboreum , the tree rhododendron, and how tremendous they can look, particularly if grown as lawn specimens. They can also look arresting grown in a woodland setting. But you might say, they are relatively slow growing and one would plant them for the next generation. Well, what is wrong with that? After all if it hadn't been for the far sighted keen horticulturalists in years gone by, we would not see the majestic tree rhododendrons that adorn so many gardens in both the old and new worlds.

Anyway, R. arboreum can look "arboresque" in ten or twenty years, with its tree-like growth, leathery leaves and rough peeling bark. Recently I peeped over the gate of our former garden at Mt. Dandenong to look at the specimen of R. campbeliiae , now reclassified as R. arboreum ssp. cinnamomeum which is about twenty-four years old, and even out of flower it presents a wonderful face to the world.

This one usually grows in a beautiful conical shape and merits a place in even a smallish garden. In early spring, embellished over a long period, with its tight charming clusters of pink campanulate flowers with dark flecks and nectar pouches, it delights the owner and visitor alike. Perhaps, like one of my very experienced gardening friends, you do not care for the combination of pink flowers and rusty indumentum. However, I cannot agree as the indumentum does not come to the fore in the flowering season, but in the unfurling of the new leaves. I see the indumentum then as an added bonus. If this one does not appeal as it should, there is a wonderful variety in R. arboreum , from the purest white to the most intense red, some with tawny indumentum, some with plastered silver, always fascinating.

If you garden in a mild climate, try the red forms, they are magnificent. If, however, you garden in a cool area, the white forms would probably be more suitable. Many arboreums suffered in the 1989 freeze in the Pacific Northwest, but the hybrid 'Sir Charles Lemon' seemed to be not so badly affected by the extreme weather as the red and some of the pink forms.

Usually with red to carmine flowers, R. arboreum ssp. arboreum , comes from very wide geographical locations, ranging from Kashmir to Sikkim, Nepal and Bhutan. This species has been in cultivation for a very long time and is reputed to have first flowered as far back as 1825, having been first described in 1805.

I grow several forms of R. arboreum in my garden, some as lawn specimens, others not quite so well placed in a border. The most interesting being those grown from seed from Sikkim and Nepal. The Nepal form with lovely plastered silver indumentum and good red flowers is a lawn specimen. The more interesting form from Sikkim with deep pink, almost red, flowers softening to a lighter pink with age, caught the attention of some American visitors to my garden last spring.

Rhododendron arboreum ssp. cinnamomeum , usually with white flowers and cinnamon indumentum seems to be hardier in cold areas than some other forms, but also grows well in milder climates such as where I live in Australia. This subspecies now includes the former R. campbelliae with its pink blooms.

First described in 1886, R. arboreum ssp. delavayi , which used to have specific status, mainly comes from China, but also from northeast India and Burma. The form I grow has glowing red campanulate flowers and dark green leaves with striking white indumentum. This one is not as treelike as some forms of ssp. arboreum , but is a real gem to have in the garden, especially for mild areas.

Rather surprisingly from southern India comes ssp. nilagiricum with its carmine flowers, whilst the related ssp. zeylanicum hails from the mountain regions of Sri Lanka. I did grow the latter with its red flowers and dark green bullate leaves, in my former garden, in a woodland setting.

Rhododendron lanigerum ( silvaticum ) usually grows as a small tree. With its early flowering rosy crimson blooms it is not really for the cold garden, but a great acquisition for milder areas. This species comes from China and northeast India.

For those who like unusual colours, a very distinctive species is the lovely R. niveum . I have been growing this species for a number of years, but it is not really tree-like with me although it is reputed to grow to twenty feet. The tubular-campanulate flowers in a rounded truss are an intriguing shade of smoky lilac. This needs care in placing - keep it away from the reds! Again the leaves have a lovely indumentum, being white on my plant. This species was first described in 1851 and is native to Sikkim and Bhutan. It is now thought to be rare in the wild.

Apart from those species in Subsection Arborea, there are many other tree rhododendrons. One immediately thinks of those magnificent species in Subsections Grandia and Falconera but they are another story. Those of us living in suitable climates will certainly grow them, and revel in their matchless splendour!

Felice Blake challenges us to see our rhododendrons in a different view. Mrs. Blake gardens in Australia growing rhododendrons of every size from the smallest on up.