Peter Cundall: On the best spots for shady characters
When asked for a solution for landscaping a steep, gloomy site on the southern side of a home, PETER CUNDALL turned to Tasmania’s naturally occurring cool-temperate rainforest for inspiration
The effect was enchanting ... the owners were delighted saying it was like living in a rainforest
Many years ago I was asked to landscape the southern side of a new home. It had been constructed on a difficult, steep site. This meant great masses of soil and clay had to be excavated from the side of the hill to create a level base.
The house finished up deeply embedded into the slope, although there was still a sizeable space between the rear of the house and a newly-created bank. Unfortunately this area was particularly gloomy and remained almost permanently wet due to constant seepage from above. Despite this, the owners wanted a selection of interesting plants to be viewed from the rear windows.
My solution was based on observations while walking through Tasmania’s cool rainforests where a wide range of underBeard storey plants thrive in extremely shady conditions with virtually no topsoil – just rotting vegetation. So I decided to plant a small rainforest in the sheltered moist gloom at the back of the new house.
After installing subsoil drainage pipes, I planted a cluster of large tree ferns, surrounding and under-planting them with dozens of smaller ground ferns and a few exotic understory plants such as Lamium (Variegated dead-nettle) and Aaron’s (Hypericum calycinum). Most were planted in irregular groups and many carefully inserted into soil pockets in the wet clay bank.
Finally the surface was covered with a thick layer of rotting, acidic organic matter, mainly pine bark and ancient sawdust. A couple of moss-covered logs were then added and finally, garden lighting and a sprinkler system installed. The effect was enchanting. The owners were delighted saying it was like living in a rainforest.
That was 40 years ago. Last time I saw the garden was about two years ago and it had hardly changed. The only maintenance needed was to occasionally prune off dead fern fronds.
Few plants tolerate gloom so at first
these places appear difficult to landscape. Yet excessively shady spots can be found in every garden, beneath large evergreen trees or shrubs or adjacent to southern sides of buildings.
Often deeply shaded areas develop over many years as dominant plants gradually monopolise the light. Most ornamental plants are affected because they need some sunlight in order to flower and in too much shade produce only leaves. Excess shade is the most common reason why many plants either fail to flower or stop doing so.
Even hardy bulbs such as daffodils and jonquils gradually cease to bloom when overhung by large, evergreen trees or shrubs.
Most large-leaved rhododendrons are normally planted in shady places, yet fail to form flower buds in deep shade, instead producing only growth buds. This failure occurs even more so with other so-called shade lovers such as camellias and azaleas.
One solution is to ruthlessly prune away overhead branches or even take out entire plants to allow in more sunlight. An alternative is to lift suffering plants and replant them where there is more light.
Other problems associated with plants in too much shade include many fungal diseases. Stressed roses trying to grow in shade are almost always attacked by powdery mildew, apart from producing few blooms.
Pests such as greenhouse thrips also love dry shade. They multiply rapidly, turning the leaves of rhododendrons, azaleas, viburnums and Lily-of-the-Valley tree, silvery as they suck out sap.
Good control is achieved by regularly wetting the bone-dry undersides of leaves where these moisture-hating pests live.
Black sooty mould on camellia or citrus leaves is a clear indication of soft scale infestation. These pests thrive on branches and leaves which receive less sunlight. Spraying with white oil gives only part control in such conditions.
Plants which are most able to tolerate deep shade include most ferns, Aucuba japonica (Japanese Laurel), Lamium spp. (Variegated Deadnettle) Hedera spp. (Ivy) and Hypericum calycinum (Aaron’s Beard).