Australian Plants for Adelaide Gardens - Mulching

Page 9 of 12

Mulching

A good method of conserving moisture in the soil is to mulch. Many mulch materials are used, the organic mulches such as pine or casuarina needles and chip litter being the most sympathetic visually.

Advantages of mulching include:

• leaves and sticks dropping from trees become part of the mulch,
• as the mulch decomposes it forms a leaf mould material similar to the natural floor of a forest,
• ground cover plants thrive in them,
• hand weeding is very easy in a friable material of this kind.

Disadvantages are:

• mulches tend to keep moisture out as well as in, so that rain in summer may not penetrate into the soil below,
• they use up available nitrogen when decomposing. This can be overcome by the careful use of a slow release nitrogenous fertiliser,
• some materials such as pine bark and needles (unless very old) contain toxic leachates. These disadvantages are rarely serious if the mulch is laid fairly thinly (5-6cm) and gradually built up as the lower layer decomposes.