Shelterbelts for Western Cape Gardens
By Anno Torr
With howling winds and salt-laden air a fact of gardening life along the Western Cape coast, it is essential to grow a shelter belt before planting the more tender plant types - without it, gardening here is almost impossible!
The most obvious and dramatic impact when one comes up from the Western Cape to coastal KZN is the sheer size and number of trees, the rampant undergrowth, and the lush, topical colour in the green leaves of all summer rainfall species. This difference in floral growth between the regions points to fundamental differences in the climate and soils of the biomes rather than to the abilities of individual gardeners! The Western Cape soils are thin, rocky and poor in the mountainous areas as a general rule, ranging from deeper, sandier soils to rocky soils along the coast. While the slopes of the mountains, where most of the Fynbos species are found, has more acidic soils, coastal gardens typically have deep sandy soils with the ph value ranging from neutral to alkaline. This is a direct result of the influence of the frequent high and salt-laden coastal winds this area receives.
With such challenging conditions, the gardener who attempts to change the soils in the hopes of gaining the more tropical and grassland look of KZN and Highveld gardens is wasting both money and labour, not to mention causing the death of living plants. Rise to the challenge and find a way to create a beautiful garden that suits local conditions, thus supporting the local conditions and associated wildlife inhabitants. To do this, an understanding of soil, wind and aspect of your garden is the first step.
The winds that occur along the Western Cape coast make it one of the most challenging areas in which to establish a garden and a shelterbelt is a vital element to any garden here. In fact, a garden cannot be created until sheltered pockets have been formed. Luckily many species have evolved to do just this – our valuable pioneer shrubs and trees. As impatient gardeners are in need of this screen sooner rather than later, there are methods of growing this screen quite quickly. This protection is needed not only against the wind but also as a way of reducing the amount of salty air the plants will be exposed to – salt is a strong growth inhibitor and even burns the leaves of the more tender plants.
Soil type in the Fynbos region is important as Protea and Erica spp., for example, won’t grow in the deep white-grey sandy soils of certain coastal areas, as they are too alkaline. Areas that are rockier, with grey to brown soils, are more acidic and better suited to the acid-loving species.
Protected wind zones are vital in this windy city and work best if created with pioneer species that readily confront the wind with no ill-effects. Try Brachylaena discolor (the coastal oak), Tarchonanthus camphoratus (wild camphor), Osteospermum moniliferum (= Chrysanthemoides monilifera (bietou), Metalasia muricata (blombos), Searsia lucida (glossy currant, blink taaibos), Searsia crenata (dune crowberry) and Aloe arborescens. In areas where the wind howls for most of the year, choose species that won’t require cutting back – a pruned screen then exposes your other plants before it grows back to the required height once again.
Plant your choice close together where they can support each other and create additional protection with intertwining branches and leaf sizes. This will also provide protected wildlife nesting areas. Only once this wind shelter belt has grown to a decent size, can you begin to introduce the more wind and salt tender perennials and bulbs.
Quick growing trees and shrubs to use are:
Kiggelaria africana (wild peach), Virgilia divaricata (Keurboom), Leucadendron argenteum (Silver tree), Vachellia karroo (Sweet Thorn), false olive (Buddleja saligna), Harpephyllum caffrum (Wild Plum). These all have tough, leathery leaves that are resistant to the damage of wind and salt-laden air, as well as the drying influence of the wind. Many have fine hairs on the leaf surface which further protects and helps to trap the moisture on the leaf, washing off the salt in the process as the condensation drips down to the root zone.
The Daisy family are Fynbos area specialists, and pioneer species from this family are very useful in creating screens: try Osteospermum moniliferum (= Chrysanthemoides monilifera) (Bush Tickberry or Bietou), the smaller Grey Bietou (C. incana), Euryops pectinatus (Golden Daisy), and Senecio species.
Other species effective in this role are the sweet pea bush, Podyleria calyptrata, Eriocephalus africanus (Wild Rosemary), the Helichrysum family and Salvia africana lutea (Beach Salvia). Buddleja saligna (False Olive), forms a fast growing screen, is highly fragrant, attracts nectar feeders, and is especially salt, and wind resistant – what a great return on investment!