A dry shade challenge

Sunday, 20 January 2013

Shrubby Begonia arborescens

Dry shade is one of the most challenging areas in a garden. I have recently offered to plant up a garden bed in a neighbour's garden that is shaded by large surrounding trees and has a lot of root competition in the soil. The garden bed is along the front of the house, so the plantings can't be too tall. I have similar areas in my own garden, and over the years I have experimented with a number of different plants to see what can cope with these less-than-ideal conditions, and for this bed I am using only plants that I can easily propagate or dig up from my own garden. Maintenance is to be fairly minimal.

Cane-stemmed Begonia Sophie Cecile

My first thought in such a situation is always of the many and various shrubby and cane-stemmed Begonia species and cultivars. They cope with shade and dryness very well once established and flower over such a long period. They grow to about 1 or 2 m height if pruned annually. Many have beautifully decorative leaves. All of my specimens coped admirably with the searing 46-degree heat of last Friday - unlike many other plants, which got burnt. I plan to put some of these at the back of the border. The flowers are generally white or a variant of pink. Also at the rear of the border I will put a white-flowered Justicia carnea, as these shrubby perennials grow very well with Begonia and also cope with dry shade. The Begonia and Justicia both need a good cut-back at the end of winter and to be fertilised at that time.

Plectranthus argentatus

I love silver plants in the shade: though most silvery specimens grow best in sun, there are a few that cope with shade, especially the Australian native Plectranthus argentatus, which has wonderfully velvet silver leaves. It can grow to about a metre tall, though it can be trimmed back at any time to control its height. There are also some more compact cultivars around, such as 'Silver Shield', and there is a groundcover hybrid called 'Nicoletta' that looks very much like the shrubby form, although I am not sure if it is directly related to it.

Ctenanthe setosa Grey Star

Another good foliage plant for dry shade is Ctenanthe setosa 'Grey Star'. It has tall, upright lance-shaped leaves of silver-grey, with dark green markings. It forms a robust clump that needs to be reined in occasionally but it is an excellent and undemanding plant otherwise. I like to grow it near the plain green foliage of Aspidistra elatior, the old cast-iron plant, which is also shade- and drought-tolerant. The foliage is of a similar shape to that of the Ctenanthe. The larger forms of Spathiphyllum can also be tried in dry shade - their leaves are similar in shape to the other plants mentioned here but they have the bonus of large white flower spathes, which last for a long time through the warmer months.

Strappy foliage can provide contrast to these bolder-leaved plants and some good candidates for dry shade include various forms of Liriope muscari. I am fond of the giant form ('Evergreen Giant') and 'Silver Dragon', a silvery white-striped cultivar of Liriope spicata , but the plain green-leaved ones provide excellent spiked flowers in late summer and early autumn. Larger strappy foliage can be provided by spring-blooming Iris japonica and summer-flowering Hymenocallis species, with its pristine white spidery flowers.

Plectranthus hybrid - Cape Angels series

All the many forms of flowering Plectranthus are excellent in dry shade and provide lovely blooms in late summer and autumn. The taller ones include Plectranthus ecklonii, with flowers of pink, purple or white; on a smaller scale are cultivars such as the Cape Angels series. Plectranthus saccatus is an excellent filler in dry shade and its purplish-blue flowers appear throughout the warmer months. Groundcovers Plectranthus ciliatus and Plectranthus verticillatus are faithful workhorses in difficult, dry spots too. Low-growing rhizomatous Begonia are also excellent groundcovers for dry shade and there is a wide variety of colours, shape and textures in the leaves of these plants, plus pretty clouds of dainty pink or white flowers in spring.

All this is still in the planning stage at the moment, as it is far too hot to be thinking of planting anything. However, the soil can be dug over and improved by the addition of organic matter such as compost and decayed cow manure, and when the cooler weather arrives, I hope to see my vision realised! Further suggestions very welcome!