Healthy soil supports the living landscape and plant collections at the Melbourne and Cranbourne Gardens.
Underneath the Melbourne Gardens is sandstone and mudstone that is millions of years old. The soil is slightly acidic with high organic content in the topsoil. Many organisms can be found in healthy topsoil including algae, fungi, bacteria, insects and worms.
A 1992 soil survey of the Melbourne Gardens found three main soil types: Deep Sandy Yellow Duplex, Loamy Yellow Duplex and Loamy Gradational.
There is approximately 15 hectares of turf in the Melbourne Gardens, providing a robust and pleasant passive recreation space. The landscape design of the Gardens is reliant upon having broad expanses of turf, which provide a visual contrast to the trees and shrubberies.
The majority of lawns are composed primarily of Kikuyu (Pennisetum clandestinum) which is a hard-wearing grass that grows during the warmer months and requires less irrigation than cooler season grasses. Unlike many gardens around the world, visitors are invited to enjoy the lawns for picnics or other social gatherings.