JARS v41n2 - Companions For My Dwarfs

Companions For My Dwarfs
Felice Blake
Kallista, Victoria, Australia

One of the more important aspects of growing rhododendrons, in particular the dwarfs, lies in choosing companion plants. Given due care in planning, the whole dwarf collection can be enhanced by its setting. Background planting, especially where necessary for protection of the more delicate rhododendrons, and, most importantly, inter-planting with choice dwarf companions are factors to consider when planning the garden. The importance of inter-planting is twofold - firstly to compliment the dwarfs with companions flowering at the same time, and secondly to add interest to the dwarf scene when the dwarfs are not in flower. Arguably dwarf rhododendrons can stand on their own merits, without companions - of course this is so, with their wonderful variety in foliage and growth patterns. But most gardeners would agree that all year round interest can be greatly increased with summer, autumn and winter flowering companions.
Although the majority of dwarfs revel in open sunny positions, which are necessary to keep the growth characteristically tight, there are some which prefer a little protection. In warmer climates, such as where I garden, when summer temperatures can rise beyond 100F., provision for shade from the hot midday and afternoon sun in summer can prove to be of paramount importance for some of the less sun hardy dwarfs such as most of the campylogynums or pogonanthums.

Shade Trees
If at all possible, shade from trees planted well away from the dwarfs is highly desirable. Trees with small deciduous leaves will save a lot of work in autumn when it is important to prevent little rhododendrons from being swamped with large rotting leaves which really must be picked off by hand.
The smaller leafed maples are good, though roots of some can be greedy, so choose with care. In my garden I have found cut-leaf birches to be good shade trees. Plant these away from the choicer rhododendrons as most roots of these trees as well as the rhododendrons are fairly close of the surface of the soil.
When we moved to our present home in Kallista in the winter of 1980, there was no shade. We were open to bitterly cold south-westerly winds that seemed to be coming straight from the Antarctic, and our garden-to-be was just an open paddock. As a first measure we built some break winds from treated pine which give a semi-rustic look.
As we knew we would need some summer shade, we planted several birches on the perimeter of the rock garden area which was to accommodate the majority of our dwarf rhododendrons. We did not follow my advice of planting trees some distance away, we just did not have time to wait for distant shade to grow. But now after quite a few years, we find that the trees and the rhododendrons under them, triflorums ( R. lutescens , augustinii and a beautiful white form of yunnanense ) as a background for glaucophyllums , co-habit quite happily. Naturally I do give particular attention to mulching and summer watering.
In this area I have also planted several species of sorbus - S. hupehensis , vilmorinii and cashmeriana . These do not cause too much bother with falling autumn leaves.

Ericaceous Companions
For the intimate areas of shade one could hardly do better than to plant enkianthus, a delightful genus of small deciduous shrubs that compliment the dwarfs to perfection. There are several species in the genus, all worthwhile with fascinating little bell-like flowers, magnificent autumn foliage and intriguing bare stems in winter. I grow E. campanulatus , cernuus rubens , the bigger flowered deflexus (which caught the eye of a recent Canadian visitor), and the most lovely white flowered perulatus , in various parts of my dwarf rhododendron area. This area is intersected with paths, with the beds mounded above the natural ground level.

Of the smaller deciduous shrubs included here, there is another rowan, Sorbus reducta - but a word of caution, it can be a lusty grower. I do have some problems with it suckering, so I keep my treasures at a safe distance. But I would not be without its bright berries and autumn tones.
One of the gems for companion planting must surely be that widely acclaimed little ericaceous shrub from Japan, Menziesia ciliicalyx , with its delightful flowers of a lovely shade of pink with a hint of purple. One could hardly praise this one too much!
Of course, other ericaceous shrublets provide so many fascinating companions for dwarf rhododendrons, one scarcely knows where to begin (or end!), but I do not merely wish to catalogue all that I grow. In suitable peaty soils with some protection, cassiopes with their ethereal lily-of-the-valley white bells are a favourite. There are many to choose from, but I would think most gardeners would agree that one of the choicest would be Cassiope selaginoides L. & S. 13284. It makes a shapely upright bush of about 9" high, has the largest bells of any cassiope, and is a good doer flowering generously every year. Other good ones not to be overlooked include the hybrids C. 'Randle Cooke' and 'Bearsden'. Nor must we overlook the American species, including the reliable C. mertensiana .
The exquisite American plant, Kalmiopsis leachiana sometimes undeservedly has the reputation of being difficult. I have never found it so, but I do grow my plants in raised peat beds (a separate area from the main dwarf area). This suits the kalmiopsis and its near relative Kalmia polifolia microphylla to perfection. As both kalmiopsis and kalmia are quite easy to strike from cuttings, with the former, in particular, flowering at an early age, it is a wonder that they are not grown more widely, but perhaps they are in their homeland.
Kalmiopsis has parented an interesting hybrid with phyllodoce as the other parent, resulting in the bi-generic hybrid x Phylliopsis hillieri 'Pinocchio'. It has much longer racemes of flowers than kalmiopisis, but to my mind is not an improvement on it! There is an increasing number of bi-generics within Ericaceae. These are fascinating to collect and add much to garden interest. All these shrublets associate well with some of the dwarfest rhododendrons such as R. 'Pipit', the smaller forms of lepidotum , some of the ludlowii hybrids including the delightful 'Wren' ( R. ludlowii x R. keiskei 'Yaku Fairy'), keiskei 'Yaku Fairy' itself, and pumilum .
Many of the gaultherias, pernettyas and vacciniums can be good companions also, provided one is careful not to plant the more vigorous spreading growers. I find Vaccinium glaucoalbum a particularly good background plant. It is attractive all the year around, more so when it is covered with its captivating berries with their grape-like bloom. An added advantage here is that they are last on the list of desirable desserts for our bird population, hence remain in their beauty for some months.
Gaultheria trichophylla and G. sinensis are delightful ground covers when placed with due care. Their main claim to fame lies in their bright blue berries. These are high on the birds' list of favourites, so really need protection which can detract from their charm.
The tiny Pernettya tasmanica is a "must" as a companion for the really tiny rhododendrons particularly in raised peat beds. I grow both the red and white berried forms.
Also in the very tiny field is the exquisite Arcterica nana with its white bells which show up perfectly against the minute leaves. This is another gem for the peat bed, easy to grow and slowly spreading by underground runners.
There are many more desirable companion plants in the great family Ericaceae, but it is up to every interested gardener to seek out those which appeal to him or her. These are just a few of the more appealing ones to me.

Bulbs
Bulbs, I find, are an essential part of my dwarf rhododendron garden, as there are many which do not object to the summer watering which is so crucial to the well-being of the dwarfs. As I write this in midwinter, I am looking out the window at the subtle beauty of the clumps of snowdrops ( Galanthus ) growing among the rhododendrons. Of course, snowdrops appeal to almost everyone, and as they need to be kept damp in summer they are quite ideal for growing with the dwarfs. One would not grow the larger leafed species and varieties such as G. latifolius (grow these with your bigger rhododendrons), but keep to G. nivalis and G. plicatus in association with the smaller rhododendrons. I grow about fifteen different varieties and they give me so much pleasure at this time of year. I do not find the dying foliage later in the season to be of any great moment.

Another exquisite bulb is the spring snowflake, Leucojum vernum . It is a treasure in the peat garden.
Also flowering early are the bright little jewels provided by Cyclamen coum , a real joy in winter. Well tempered, they associate beautifully with the snowdrops. These two make ideal companions for the early flowers provided by Rhododendron moupinense and R. leucaspis .
Of course, everyone would agree that Cyclamen hederifolium is indispensable for late summer and autumn colour, but one has to remember that they can grow large in due course. Old corms can sport leaves and flowers covering more than a foot in diameter, so one needs to exercise a little care in placing these among the dwarfs. This is not a problem with C. coum . C. repandum , cilicim and purpurascens also demand attention as desirable dwarf companions.
Although we usually associate crocus with the need for a baking in summer, I do find some do not object to summer watering, and add interest particularly in autumn. Crocus banaticus (iridiflorus) with its fascinating flowers, quite uncrocus-like, with the inner segments being shorter than the outer three, looking rather like a tiny iris, and a beautiful rich lilac, is one that really must be kept damp in summer, so it is ideal. I also find Crocus pulchellus is a good doer in spite of summer watering, rewarding me by flowering freely with its delicate pale lavender flowers penciled in a deeper shade. It self-sows among the lapponicums in an open and very sunny area. Spring flowering crocus can also be tried, but be a little cautious with the ubiquitous C. tomasinianus . This one can spread with wild abandon and come up in the middle of your treasures. No dwarf rhododendron really cares for its companions at close quarters, always leave the root area free.
In our climate I find the various forms of Rhodohypoxis baurii a truly wonderful asset in summer. It provides clumps of little white, pink and red flowers, only a few inches high, for months on end among the dwarf rhododendrons. These, too, appreciate summer damp. I understand that they can be a little difficult in climates with very cold winters, as they can be susceptible to heavy frost, but they are certainly worth the bother of lifting in autumn and replanting in spring, when necessary. There are now a number of named varieties available that are well worth seeking out. Among the best would be 'Pictus', pale pink in the bud opening white - this one is a prolific increaser. The pinks range from the pale 'Dawn', through to the deep pink 'Margaret Rose', via mid pinks of 'Susan Garnett-Botfield', 'Fred Broome' and 'Stella'. The reds include 'Albrighton' and 'Great Scot'. I would not be without numerous clumps of these throughout the garden in sun or semi-shade.

Amongst, I would say almost foremost amongst, the suitable companion bulbs would be the delightful erythroniums. All these look most charming with their little lily-like flowers in shades of cream, pink, violet and yellow, relishing semi-shade generally, self-sowing when happy. The earliest to flower for me is the violet flowered E. hendersonii , the buds of these show in winter nestling in the beautiful trout-marked leaves. Next to flower is the rather bright yellow E. tuolumnense , this one quite enjoys much more sunshine, in fact it seems to need sun to keep it flowering and increasing. Although this one is a "useful" addition, personally I do not rate it as highly as other species such as E. hendersonii , oreganum , californicum , grandiflorum and the exquisite pink revolutum , or some of the hybrids including 'Pagoda'. You in America would know much more about erythroniums than I do as you have so many more species available than we have in my country.
Another American treasure I would not be without is one of the smaller trilliums, T. rivale with its delicate pink spotted flowers. These are quite at home with me growing among the pogonanthums, and elsewhere in coolish spots. I do grow other trilliums, but I feel that T. rivale is particularly charming with the dwarf rhododendrons. The bigger trilliums naturally make good companions for the bigger rhododendrons.
The well-known snakes-head fritillary, Fritillaria meleagris in both its checkered purple forms and its entrancing white form also make ideal companions, and again enjoy summer watering. These begin to grow early in the season. The pale yellow F. pallidiflora is also suited to a dampish spot among the dwarfs.

One should not leave the great family Liliacea without touching upon liliums. We do grow a large number, about a thousand, in our garden. However the great majority of these are our own seedling Orientals which make most magnificent companions to our larger rhododendrons. (See ARS Journal Vol. 40:4, Fall 1986). But to get back to liliums suitable as companions for the dwarfs, my favourite is L. mackliniae . It is enchanting with its wide bell shaped drooping flowers, "a delicate shell pink outside, like dawn in June, with the sheen of watered silk; inside like faintly flushed alabaster" (so wrote its discoverer, Kingdon-Ward). This is Kingdon-Ward's 'Manipur Lily', discovered in 1946 on the Indo-Burmese frontier. As it grows up to about four feet, it is better suited growing among the glaucophyllums or trichocladums. At the small end of the scale, the very patient could try L. nanum , a little gem of about nine inches, with a purplish bell shaped, often solitary flower. This one takes some years to flower from seed, but is worth the wait! The pink L. rubellum to about two feet is another suitable lilium. Those people who grow Rhododendron nakaharae often find the salmon-red colours of this little azalea hard to fit into the dwarf scene. Fortunately it is late flowering, and one little lilium, L. pumilum , makes a fine companion with its red turkscap flowers. The little scarlet Lapeirousia cruenta can also add to the picture in a sunny part of the garden.
Some dwarf narcissi appreciate damp conditions. Who would be without the delightful N. cyclamineus , with its swept back petals, and the various hoop-petticoats, forms of N. bulbocodium . One particularly charming dwarf narcissus, 'Quince' is a companion in my garden to R. canadense with its delicate mauve fairy flowers. Together they form a dainty cameo. There are many combinations one can try.
Scillas, too, can provide a little patch of pale or bright blue. These do not seem to mind some summer damp. As all these bulbs are planted in our acid soil, I add bone meal at the time of planting. I make sure the sun loving bulbs are planted among the sun loving rhododendrons.

Perennials
Some perennials are, I think, essential among the dwarfs. To begin with surely the gentians would be close to the top of the list, and in particular the lovely autumn flowering ones such as G. sino-ornata and the free-flowering hybrid 'Kingfisher'. In my garden these require a coolish spot with morning sun - they do not appreciate very hot afternoon sun in summer. Also worth growing and much more sun hardy are G. septemfida and the long-flowering x 'Hascombensis'.
For another spot of brilliant blue, I find that the supposedly lime loving Polygala calcarea grows equally well in our acid soil, and looks lovely when flowering among the dwarf rhododendrons. It also obligingly self sows, but does not become a nuisance. Forms of the shrubby little Polygala chamaebuxus too make good additions in semi-shade with their little yellow and white or yellow and purple pea flowers. I really prefer the yellow and white form which seems to have a charm somehow lacking in the more vivid yellow and purple forms.
Some campanulas also look well, provided one chooses the small, not too rampant species. I find C. aucheri very well behaved and non-running. Its light blue flowers compliment the dwarfs. The hybrid x 'G.F. Wilson' is another interesting one with its deep violet blue flowers, but this will run around a bit. A hybrid of C. raineri with large upturned bells of deep blue is another favourite and flowers for a long time in summer. There are many more from which to choose.
No garden that has a suitable spot should be without a selection of primulas and meconopsis. Who would dispute the claim of the lovely old-fashioned primrose to be included? I have a great love for these. The pale yellow ones always light up the garden in spring. There is a wide range of colours these days, but I cannot enthuse over the more garish very modern hybrids, give me the yellows, pinks, blues and just the occasional red and purple! The variety of primulas is legion. For the real lovers of moist spots, one can always create suitable conditions by sinking a piece of plastic in the soil deep enough to accommodate the roots, forming a miniature bog garden. Do not forget to pierce a few holes in the plastic so that the soil will not become stagnant. It is wonderful how this simple method can help to widen the selection of varieties one can grow successfully in the garden.

Most people when thinking of meconopsis think of the Himalayan blue poppy, M. betonicifolia , and quite naturally too! But do not overlook the other charming species, such as M. regia which delights you with its magnificent rosettes of ferny leaves for several years before bursting forth into stems, comparatively tall, and long lasting, of primrose yellow poppies. But alas! it is mono-carpic, so one has to begin all over again. Another yellow flowering poppy is M. dhwojii , and there are others well worth seeking out. All these are best in semi-shade, at least in our climate, and are suitable among the glaucophyllums, or perhaps for R. lepidostylum and its kin.
Two little iris demand attention, one is the incredibly dainty little Japanese I. gracilipes with its grass like foliage and fine wiry stems carrying lilac-blue dainty flowers with a touch of gold on its crests. Another is the little I. cristata with almost stemless flowers in a different shade of lilac-blue.
The choice of companions is infinite, more and more come to mind. One must not forget the pretty little autumn flowering snowflake, Leucoium autumnale , for a sunny spot, or another autumn flowerer, the eye-catching colchicum in either sun or semi-shade. They have gorgeous upfacing tulip like flowers in all shades of mauve and purple with an occasional white one. These are more suitable among the slightly bigger rhododendrons such as the glaucophyllums, the racemosums or the trichocladums. They do have one big drawback, their foliage which follows in spring is apt to be a bit coarse. Then again for shady spots, where there is sufficient room, the wood anemones, Anemone nemorosa , will delight you.

There are so many companion plants to choose from and each of us has our own favourites. As the flowering times of both rhododendrons and companions vary from garden to garden, it is really necessary to keep notes of the flowering times in your garden, so that the selection of companions can be made more meaningful. One can then plan complimentary combinations, making a series of delightful scenes through the garden. In fact I sometimes wonder which gives me the greater pleasure - my dwarf rhododendrons or their companions!

Felice Blake, a regular contributor to the ARS Journal grows a wide variety of companions plants among the rhododendrons in her Australian garden.