The Arboretum, (near the Place of Quiet), is a project of the Friends of the General Smuts Foundation. A variety of indigenous trees and shrubs are being planted to attract birds and butterflies to the area. 

When Smuts moved to Doornkloof he planted exotic trees such as blue gums and pine trees to assist the mines, and augment his income. The Australian wattles were planted by Ouma Smuts, who liked the yellow flowers. 

Today these exotic trees, which are classified as invasive plants are slowly being removed and replaced with indigenous trees. The natural grasslands have recovered over time and the wild flower display in Spring is worth the walk.