Companion Plants: Ferns in the Rhododendron Garden
North Vancouver, British Columbia, Canada
Reprinted from the Rhododendron Society of Canada Atlantic Chapter newsletter
Ferns are among the earth's oldest vegetation and dominated the plant world about 200 million years ago. Botanists generally agree that there are about 10,500 species of ferns widely distributed throughout the world. They range in size from 4-6 centimeters to 10 meters.
The parts of a fern consist of fronds, the crosiers (fiddleheads), rhizomes, and roots. The rhizome is the vital part of the fern as it contains the growing point of the plant. Ferns grow from spores, which are quite different from seeds. Spores develop in the fruiting body found on the undersides of fertile fronds.
Ferns are produced in a two-generation process. The spore germinates to form a flat green cell mass called a "prothallus." The prothallus produces both male and female organisms. To produce the first small frond, the male organism must fertilize the egg within the female organism. At this point the prothallus wastes away, and, if conditions are right, the little fern will continue to grow.
Ferns can be deciduous or evergreen. Some native Nova Scotian ferns remain green in mild winters but sensibly turn deciduous in harsh winters. Anyone who walks through the woods during our winters can observe the fact. One year, the forest floor will be quite green with ferns; another year the fronds will be brown and withered. Here on the West Coast, Polystichum munitum, the Western sword fern, is a durable evergreen.
Ferns were most popular during the Victorian age. Ferneries were a feature of most English gardens of that period. People were mad to collect as many different ferns as they could. One of the fascinating characteristics of ferns is their ability to sport, and sports were jealously guarded. Large collections of ferns were kept both outside in the garden and under glass. The wealthy were able to employ gardeners to make sure that optimum conditions were maintained for the growth of their ferns. Even in summer coke-fed boilers were kept going to maintain the proper amount of humidity for ferns kept in glasshouses.
However, with the changed economic conditions after World War I, labour-intensive gardens became a luxury few families could afford. Fern collections suffered, or were completely lost to the next generation of gardeners. Today there is a renewed interest in growing ferns. Here on the West Coast there are a few nurseries which specialize in ferns, and most good garden centres have a fern section. Gardeners are able to see for themselves the diversity and beauty of ferns. I read somewhere that ferns have impeccable manners: they associate well with other plants and with one another. Aesthetically they contribute a lot to most gardens. Ferns have a calming and a timeless quality in the garden. At the same time, ferns can be very utilitarian. They grow happily in places where it would be difficult to establish any other plant.
As a general rule ferns like some shade, humidity and shelter from the wind. They like soil high in organic material with constant moisture but free draining. The soil, ideally, should be slightly acid. These, of course, are also the ideal conditions for growing rhododendrons, and well designed rhododendron gardens always contain a selection of ferns. The classic form and quiet beauty of ferns make them a perfect foil for the blowzy beauty of rhododendron flowers.
Ferns vary a great deal, which means that there are many to choose from to work into a mixed border with rhododendrons. The following are a few rules you might like to consider before planting. The size of the fern should be appropriate to the size of the rhododendron and companion plants. For maximum effect in the garden, group plants of one cultivar. Contrast of texture is an important consideration. Some ferns look hard and polished, while others are light and airy. And, of course, there is colour. Never forget that green is a colour, and its many shades should be used to complement the garden.
I am not going to go into a long list of ferns; after all, half the joy of gardening is experimenting and deciding what suits your taste. However, the following are a few suggestions you might like to take note of. Adiantum pedatum, the maidenhair fern, has delicate wire-like black stems. The fronds create a soft texture in the garden. It would combine well with Rhododendron mucronulatum and Viola cornuta 'Alba'. This violet has pure white flowers and if cut back during the growing season will produce a second crop of flowers.
Athyrium niponicum pictatum, the Japanese painted fern, is a lovely, rather unusual fern. It has silver-flushed, soft green foliage with deep red stems, it needs a sheltered spot but with lots of light. Try it with R. 'Mist Maiden', Asarum europaeum, Lamium maculatum 'Pink Pewter'. Polystichum braunii, Braun's holly fern, has fronds which are ruffled with a bristly edge and hairy stems. New foliage has a hard metallic sheen. A combination you might try is R. 'Ice Cube', Primula veris and Hosta 'Shade Fanfare'.
Osmunda regalis var. regalis 'Christata' is a selected form of the royal fern. This fern needs plenty of room, as it will grow to be a large specimen giving a tropical touch to the garden. Try it with one of the large hostas such as Hosta 'Krossa Regal' and Astilbe 'Bronze Queen'. You will need a large rhododendron, such as R. maximum, to hold its own with this combination of plants. The idea is to make the most of your ferns in combination with other plants.
Reginald Kaye in his book Hardy Ferns describes ferns as "a large group of plants which cannot be surpassed for furnishing dark and shady places of our gardens; plants which have inherent grace of form, ease of cultivation, require a minimum of upkeep, are immune to most garden pests, and provide a never ending source of interest." Once you start planting ferns in your garden I am sure you will agree with Mr. Kaye.
Carol Dance, a member of the Vancouver Chapter, recently moved to the West Coast from Nova Scotia.