Capetonians need to end their love affair with the English country garden and embrace plants and gardening skills suited to our thirstier climate, says garden guru Marijke Honig.
Author of Indigenous Plant Palettes, Ms Honig was guest speaker at Cape Town’s first Book Revue on Friday November 3.
She said gardens and gardening practices suited to temperate northern hemisphere climates made no sense in Cape Town with its hot Mediterranean climate and up to eight dry months a year.
The Book Revue is the brainchild of publisher Pippa Smith with her business partner, Camilla Twigg.
The concept is to interview authors about their books covering a variety of topics from politics to fiction, during the daytime and the evening, at various locations.
After running successfully in Johannesburg for eight years, a function was due to be held in the grounds at Ferndale Nursery, in Constantia. Instead it rained and about 50 bookworms sat inside.
Ms Honig, a landscape designer and botanist, has worked at Kirstenbosch for several years and now works from her Newlands home.
She spoke about the future of gardening and ways of making a positive change.
She admits to being climate-change sceptic until recently when the scientific data finally convinced her otherwise.
Dr Peter Johnstone is one of the scientists behind that data.
Based at UCT’s Climate System Analysis Group (CSAG), he says Capetonians must realise that we can’t have green lawns all year round.
“We need to adopt a more sustainable view towards gardens so that any plants we have (fynbos, for example) can survive dry periods, but also be prepared for heavy rains they come, mostly by storing that water, but also by having permeable layers surrounding our houses so that the excess run-off water can seep in and return to the aquifer.
“And while Cape Town will not become a barren desert, there’s nothing wrong with a living desert – see places like Tucson, Arizona, where green lawns are banned, gardens are dry, but there’s enough water, and it’s really beautiful in its own way.”
Back in 2012, Professor Guy Midgley, also of CSAG, said one of the strengths of their research was that it had increased the confidence of the climate-model projections, which suggested that the Cape would become more arid. And it has.
During her talk, Ms Honig said weather patterns were becoming increasingly harder to predict with “wild swings” from one day to the next and more extreme weather events.
“Multiple days of soaking rain are a thing of the past although worldwide there is more flooding which means the loss of much topsoil.
“Winters are milder. However it’s important for plants to go through dormancy, of winter rest as seen with olives which are producing dramatically less fruit than before. The knock-on effect disrupts insect pollinators.”
She said raised CO2 levels cause “atmospheric fertilisation” – woody plants grow faster with higher CO2 levels.
“From aerial photographs, scientists are seeing bush encroachment and fewer grasses compared to 50 years ago when CO2 was lower,” said Ms Honig.
With the drought making it impossible for those without boreholes to water their gardens, she suggests it is time to reassess your garden and plan:
* Reduce hard surfaces by using permeable paving and allow groundwater recharge. This is also good for trees and keeps the ambient temperature down. Use stone and natural slasto cobbles.
* Use evergreen plants such as searsia varieties and spekboom, as they need no irrigation and can survive on rainfall.
* Do not pamper plants with irrigation and fertiliser.
* Do not force plants and their seeds to stay where they are – allow them spontaneous migration and they will find the most suitable place.
* Do not choose plants for their look but rather for their suitability to a site. Consider valuing plants for their resilience and ecological function, in addition to personal preference.
* Be open to water-wise exotic plants. * More is less – plant more of what is doing well.
* If you have a borehole, install a water meter so that you can monitor water usage and detect leaks. A resource cannot be managed effectively unless it is measured, and smart meters offer the convenience of real-time data on a hand-held device in your home. Water deeply and infrequently. Mimic a good rainfall event of say 50mm and really saturate an area, with water penetrating at least 50 to 60cm into the soil. You may only need to do this every three to four weeks.
* Plan water-use zones in your garden and irrigate accordingly.
* Designate a zone for no irrigation – plants that will survive on rainfall.
* Blanket spray irrigation is a thing of the past – it is highly inefficient and wasteful. If you are irrigating, plan to water once every three to four weeks to encourage roots to go deep and not two to three times every week, which encourages surface roots.
* Mulch all planted areas with a 5 to 10cm thick layer of chipped wood and leaves as this dramatically reduces water loss from the soil surface and keeps it cool. Mulch also feeds the soil and your plants.
All green areas – whether planted landscapes, wild areas, or a road verge with weeds – contribute to the urban ecosystem and are vital to our well-being. Green areas produce air for us to breathe, they filter pollution, absorb stormwater and reduce flooding, purify water and maintain a pleasant temperature. Due to the many tarred and paved areas, and reflective surfaces from tarred roads and glass buildings, the city heats up.
“This is known as the urban heat island effect and means that pollution levels rise and our quality of life decreases. On summer days, especially when there is no wind, the raised temperature is already evident in the City Bowl, which is a few degrees hotter than the suburbs,” said Ms Honig.
For more information about the Book Revue, contact Pippa Smith on firstname.lastname@example.org, or 083 704 2219.