#GROW

​​Sustainable gardening with Keith Kirsten

A Q&A with expert horticulturalist and gardener Keith Kirsten about gardening sustainably in South Africa

JAN 24, 2022 | Written by Zoë Chapman Poulsen. Photographs by Keith Kirsten and Ray Hudson

Right: Keith Kirsten. Left: Replace hard paving with gravel, also as a substitute for lawns.

With the key aim of gardening in a way that minimises our impact on the earth, sustainable gardening helps us to benefit the environment around us. But what does it mean for gardening in the South African context?

Expert horticultural and gardener Keith Kirsten recently gave a talk to the Botanical Society of South Africa’s Algoa Branch about the importance of sustainable gardening. For this edition of the BotSoc blog, we chatted to him about his thoughts on the subject. Keith Kirsten was interviewed by Zoë Poulsen.

Above: Indigenous fynbos garden in full bloom at Cavalli Estate near Stellenbosch in the Cape Winelands. Photo by Ray Hudson

Sustainable gardening is a concept often described as having no technical definition. What does it mean for you in a nutshell?

For me, sustainable gardening is all about working with nature and wildlife and creating a sustainable future, without being cliched about low maintenance gardens. The beauty of sustainable gardening is that it is lower maintenance. There’s no doubt about it. Therefore, you know you are truly working with nature by doing it that way.

What are the most important core principles of sustainable gardening?

The most important place to start is by looking at the climatic conditions of the region, and the area where you are going to garden. You also need to design the garden sustainably as well. You can do this by making sure that you don’t have more paving than you need, more lawn than you need, or more trees than you need. Water recycling should also be incorporated into the design of the garden. Then you need to plant sustainably for the climatic conditions.

When maintaining your garden, you need to practice sustainability. This includes watering your plants deeply, not spraying your garden with pesticides and making your own compost. If you have space, then you can grow your own vegetables. Then you can eat sustainably too.

Above: Indigenous and waterwise fynbos planting at Boschendal in the Cape Winelands. Photo by Ray Hudson

How have you brought sustainable gardening practices into your own garden?

The property was originally an old sheep farm, and I have converted the old sheep meadows by simply allowing them to grow back naturally. I have been inspired by visiting many different gardens around the world, including the Dutch landscape designer Piet Oudolf. In the wild grass garden, I have stopped mowing, but we have winding mown pathways. There are lots of Aloe cooperi that are currently in bloom. We’ve also got Crinum, Agapanthus, and Kniphofia.

At the border of the grass garden, we have trees including the stinkwood (Celtis africana) and the tree fuschia (Halleria lucida). We have many birds that visit including Francolins. We have ants and termites in the lawn, but we don’t do anything about them. When the grass grows longer, then it becomes full of wildflowers.

Top left: Blue thatching grass (Hyparrhenia hirta) in Keith Kirsten’s wild grassland garden. Top right: Grass Aloe (Aloe cooperi). Bottom left flowers of the herb Tansy. Bottom right: An example of wild grasses colonising kikuyu lawn that has been left unmown. Photos by Keith Kirsten

How does sustainable gardening help us to garden with our environment?

If a garden is a monoculture, you’re not going to have wildlife coming into it. Sustainable gardening is all about having a variety of plants in our gardens for biodiversity. Each of these plants plays their own role in the garden. Some provide nectar for birds, some attract other pollinators.

That doesn’t mean to say that you should have a ‘fruit salad’ with one of everything. You should try and group a few of the same things together. So, you might have some Agapanthus, and then some Pelargoniums and all the lovely indigenous plants. You might include some Crassulas and other succulents. There are no hard and fast rules. If you love a specific plant group, because you just love the fact that they are living creatures, then have as many as you like. But you can try and melt them all into one picture like painting a painting.

Above: Indigenous fynbos garden with restios and Agapanthus at Lourensford Wine farm. Photo by Ray Hudson

Above: A soft and informal indigenous planting of restios and red hot pokers (Kniphofia) at Cavalli Estate. Photo by Ray Hudson

Should xeriscaping be one of the goals of sustainable gardening? Does a sustainable garden have to be lots of gravel, prickly cacti and succulents?

If you are living in Arizona or the middle of the Tanqua Karoo then you would garden in a different way and then you would go with xeriscaping. In these more arid areas you can still create a beautiful garden. But a garden should never have more than 10-15% paving, because it creates heat. A garden shouldn’t be cluttered with too many pots and plastic synthetic lawn and too few plants. You know, it is the green stuff that feeds your soul. It’s the trees and the shrubs and a beautiful bird bath that attract wildlife.

Which gardens that showcase the practice of sustainable gardening most inspire you, and how can they inspire others?

Many of our spectacular national botanical gardens around the country can be used as a guide, so that gardeners can see what they can plant. In Cape Town you’ve got Kirstenbosch National Botanical Garden. Here on the highveld you’ve got Walter Sisulu National Botanical Garden. Further east there is the Lowveld National Botanical Garden which is also stunning.

But in every town or city around the country there are stunning indigenous gardens that inspire, that can be visited during many of the open garden events. There is the Bedford Garden Festival and the Hogsback Open Gardens Spring Festival in the Eastern Cape. Anyone who would like to start a fynbos garden should visit Cavalli Estate in the Cape Winelands near Stellenbosch. It’s a beautiful example of a fynbos garden. To see a great garden with a bit of art and indigenous plants, visit Henk Scholz’s garden in Franschhoek. All of these wonderful gardens will inspire you.

Above: Wachendorfias in bloom in an indigenous wetland garden at Lourensford wine farm. Photo by Ray Hudson