Cape Town - Whether your garden is affected by north-westerly winds or the infamous Cape south-easter, wind is a major issue for most gardeners on the peninsula.
The impact of wind on coastal gardens varies from place to place. In exposed areas, coastal winds have the potential to cause extensive damage throughout your garden if you don’t plant wind-friendly plants.
Emerging in False Bay, south-easterly winds funnel through to the City Bowl and sweep across to Blouberg. However, in the Vredehoek area and the City Bowl, winds of up to 160km/h can be devastating for plants.
Before planning your windswept garden this spring, take a good look at the landscaping at the Waterfront, or in the biodiversity gardens around the Cape Town Stadium, and you’ll see evidence of experienced, wind-friendly landscaping by professionals who know what works.
Benefits of wind:
Gardening in the wind is not all bad; there are some distinct benefits. Wind brings a constant supply of fresh air to your garden. It renews available carbon dioxide, which is present in small quantities in air and is one of the main raw materials required for a plant to photosynthesise.
Wind also has the advantage of keeping fungal diseases and pests at bay. First, it keeps spores off leaves by keeping the leaves dry (spores germinate on damp leaves) and, second, wind makes it difficult for insect pests to stay attached to plants.
Air movement around plants is also vital to facilitate osmosis (sap flow) in all plants.
“As the air moves over the leaves of the plant, it draws moisture out of the plant, which evaporates. This process is known as transpiration,” local horticulturist Allan Haschick explains.
“As the plant transpires, it draws vital nutrients and water from the soil through the plant. The evaporation (transpiration) of water also keeps plants cool.”
Salt damage:
Moist, salt-laden air brought at least a kilometre inland will potentially damage plants in gardens.
Salt is deposited on the leaves and shoots of plants, where it builds up over time. These high salt levels have a dehydrating effect. Combined with frequent wind, the salt gives rise to further burning.
“Wind can also dry out the soil, and damage occurs when there is not enough water available for the plant to replace transpired water. This results in the burning of the leaf edges or even entire fresh new shoots,” Haschick says.
So what should you do if your garden is exposed to the big winds each summer?
“Start by choosing wind-hardy plants for your garden. While the range is not great, your plant losses will be dramatically reduced if you start by choosing the right plants,” Haschick says.
When rejuvenating your windswept garden this spring, start with small plants. Small plants adapt well to prevailing conditions, and are easier to shelter. Large plants catch the wind, and will burn far more easily.
Wind-friendly plants:
There is a limited range of proven wind-hardy shrubs you can use to create a screen.
Try the indigenous coastal silver oak (Brachylaena discolour), camphor bush (Tarchonanthus camphoratus), bush-tick berry (Chrysanthemoides monilifera) and num-num (Carissa macrocarpa), or the exotic but useful mirror bush (Coprosma repens) and salt bush (Rhagodia bastata). As these shrubs grow, you will be able to plant a wider range of plants in the shelter they provide.
There is a range of fynbos plants ideally suited to windswept gardens, including the Cape reeds, which will allow the air to filter through your garden.
Also, seek out grey-leafed plants such as lavender, lamb’s ear (Stachys byzantina), gazania, arctotis and helichrysum.
Plants with thick, waxy or glossy leaves usually tolerate strong winds. The waxy layer that covers the leaves of the coprosma, pelargoniums, aloes, Indian hawthorne (Rhaphiolepis spp.), milkwood (Sideroxylon spp.) and num-num (Carissa macrocarpa) also protect the plant from losing too much water.
Once you’ve chosen your plants, consider planting them closer together than you would in a suburban garden.
Growing in a group, plants will provide physical support for one another against the wind.
You can even overplant and remove the unwanted plants when they have grown too big.
Stake every new plant well, inserting the stake deep down. Strong wind often keeps the root ball loose from the surrounding soil, making it difficult for the plant to become established.
Apply a 10cm layer of mulch across all the beds in a windswept garden.
Placing a thick layer of compost or bark around each plant will trap moisture, keeping the roots cool and moist.
Finally, plant up a living mulch around the base of each newly-planted shrub or tree to provide shelter and shade.
Try arctotis, pelargonium, gazania or osteospermums – they are easy to grow and fast-growing. - Weekend Argus