Marvellous Mulch: Australia is the world’s driest continent and water is our most precious resource. All gardeners should strive to save as much water as possible as they pursue their horticultural activities. Growing Australian plants will reduce water usage because our native plants are adapted to survive in our harsh and drought-prone environment. Even those gardeners who favour exotic, thirstier plants have the opportunity to reduce the amount of water needed on their gardens.
The use of mulch is the way to reduce water usage in the garden. A layer of organic material, on the surface will significantly reduce evaporation and thus reduce the amount of watering. Mulch has a secondary advantage in that it helps to suppress weed growth.
What materials should be used as mulch? There are a number of organic materials suitable for the purpose. Before we go any further we should mention one material that should not be used. Black plastic seals the soil, so that there is no interaction with the atmosphere. Eventually this material will sour the soil and inhibit plant growth.
In the past we have used sawdust extensively and this material has worked very well. When spread to a depth of four centimetres, sawdust reduces evaporation significantly and also gives weeds a hard time. Recently sawdust has become hard to acquire in large quantities and we are now using chipped green waste from the local Council. This material consists of branches and foliage that have been broken down after being past through a chipper. The chipped material is stockpiled and when delivered is semi-composted.
The chipped material is spread to the same depth as sawdust. The mulch is spread over the whole garden bed. It is formed into a shallow depression around each plant to concentrate water. Some gardeners insist that mulch is kept away from plant stems. We have had no trouble with mulch coming into contact with stems.
We have been using chipped material for about 12 months and have found it has some advantages over sawdust. It is heavier than sawdust so that on our windswept hill chipped material does not blow away. The material is dark brown in colour and in winter tends to absorb heat and warms the soil. At times we have problems with rabbits digging in the garden beds. They do not like digging in chipped material so rabbit damage is considerably reduced.
The only down side is that it is slightly more expensive than sawdust.Wood chips and hay have also proved to be satisfactory mulching material. A number of local gardeners use these materials.