Hot, Dry Wall Displays
Hot and sunny wall gardens are notoriously difficult to plant up successfully. Temperatures ratchet up a notch as heat radiates off the walls and surrounding paving. Beds are commonly narrow and soil depth shallow, so soil dries out rapidly, and nutrients are quickly exhausted. And rainfall misses the mark if the bed hugs the house beneath the eaves. As if these challenges are not enough, bright light bounces of pale-coloured walls, sufficiently intense to burn the leaves.
So, what plants will survive these conditions? The best candidates for the job are water-wise species able to take a fair amount of neglect and low nutrient soils. Many succulents fall into this category.
Aloe ferox is famously tough, standing strong in the face of coastal winds, frost and arid conditions.
Beautifully sculptural, it is the perfect focal point drawing you up the stairs. Leaf diameter can spread, so make sure to there is space around it to walk. Flowering takes place from around May to August but can stretch to September and November in the cold northern reaches of the country. It is a perfect plant to bring insects and birds close to the house. At its feet, tumbling in soft folds over the wall, is the smallest Pelargonium shrublet, P. tongaense. Found naturally in shaded areas in Tongaland (north-eastern Zululand) in sandy soils, it is very adaptable to a variety of garden conditions and is more than happy in full sun. A walled garden provides the dry conditions it prefers, especially in winter when the foliage thins out. Deadhead occasionally, but allow a few flowers to go to seed to encourage germination of fresh, young plants.
In a low, tiered wall hugging the length of the house, a colourful succulent spread thrives.
Othonna carnosa, now Crassothonna cacalioides, immediately grabs your attention, flowing over the lip of the wall in a tight curtain of narrow grey-green leaves and bright yellow buttons. Quite stunning as it spreads around the maroon leaves of Kalanchoe thyrsiflora. A few young Crassula ovata stand behind this focal arrangement; I call them the little old men of the Crassula family, stems becoming gnarled with age. 1.8 x 1.5 m is a typical mature size for this shrub, but growth speed is slow, and it is thus easy to control and keep growth in check with judicious pruning. In a hot, shallow bed, it is probably even slower. White and pink flowers cover the gleaming foliage in winter. Alongside, tall peach-yellow spires of Aloe vanbalenii cast their elegant shadows against the wall, with just a couple of Rhino Thorn stems squeezed in front. The thorny Euphorbia grandicornis can grow large in a regular garden bed, and its inclusion here is interesting and so attractive with tiny yellow flowers squeezed together along the margins of the stems. A word of warning; the spines are ferocious, an evolutionary response to limit browser interest. It enjoys summer rains and dry winters.
Flexible stems of a white-flowering Wild Dagga, Leonotis leonurus grow every which way, always worth a place in the garden, and very easy to prune into a neater shape if desired. Tucked neatly into the corner at the top of the stairs, is Senecio barbertonicus, lemon yellow flowers and narrow grass-green leaves in beautiful contrast to the purple pots on the wall behind. Yellow flowers are abundant in a dry winter and loved by insects. Size is between 50 cm and 1.8 m depending on growing conditions and holds its shape well. It is drought hardy and will handle a mild frost.
Cotyledon barbeyi, with narrow, paddle-shaped leaves and gorgeous orange-red to pinkish-red pendulous bells, fronts a natural wood statue; a single Aloe chabaudii behind, surrounded by a small spread of Aloe parvibracteata and Bulbine latifolia looking remarkably good in the hot sun. Other companions are Berkheya speciosa and Crassula capitella, Crassula multicava, and a very young Aloe marlothii.
Dynamic changes lie ahead for this small space, and it will be quite a pleasure to watch.