It's hard to believe, on a sweltering Durban day, that glacial deposits are being used to beautify a corner of Durban Botanic Gardens. But 10 dwyka tillite core rocks, weighing between one and two tons each, stand among a range of succulents.

Durban landscape gardener James Hallé is excited about the new additions to the succulent garden he is revamping – the rocks date back 300-million years and were formed when KwaZulu-Natal was still part of the Gondwana supercontinent.

Dwyka tillite rocks are found mainly in our province and before being transported in three large trucks to the gardens, the designated rocks were used as a barrier between the street and the grassy bank under the Sherwood interchange.

Hallé spotted them and thought they were just what he needed for the new African-Madagascan succulent garden at the St Thomas Road entrance of the gardens – and was even more excited when he learnt of their origins.

“They are awesome and I was so fortunate to be able to use the trucks to get them here,” he said.

Before the revamp, the garden was a 50m sweep of aloes that visitors would pass with hardly a glance. Hallé plans to plant a variety of succulents, in keeping with the gardens’ focus on African flora. South Africa has the highest number of succulent flora species on the planet and this will be an opportunity to showcase some of them, as well as Madagascan succulents and aloes. A corner of interest is the spiny forest of Madagascan shrubs.

There is even an alien there – the first Jacaranda to be planted in South Africa, in 1882 stands among the succulents. Although it has been declared a weed, it is not invasive in Durban, so it will stay as a piece of history.

Hallé is creating a cobbled staircase of stones, and a bench and gazebo will entice visitors to make use of the garden. Two metal circles that were part of an eThekwini display at the Chelsea Flower show some years back have been incorporated as a feature, too.

“We want to give new life to existing materials,” says Martin Clement, curator of the gardens. “We could have brought in generic materials, but decided it was better to recycle what we have. We want to create a bold garden that celebrates horticulture.”

The revamp is a collaboration between Hallé, Durban Botanic Gardens Trust and eThekwini Municipality’s Parks and Recreation Department and Electricity Departments. It is the beginning of several areas in the gardens that will be upgraded.

Sibusiso Mkhwanazi, senior manager, natural resources and special services, at the Parks and Recreation Department, says the new succulent garden will provide a welcome at the St Thomas Road entrance.

“This is not just change for the sake of change,” he says. “We have a master plan and will be making the gardens more user-friendly. We are using existing materials as much as possible and recycling. We plan to improve the signage so that it is consistent in its appearance.”