Australian conditions are often hot and dry, and conserving water is a necessary part of tree and garden maintenance. One of the best ways of protecting soils from evaporative water loss is to mulch, and there are a variety of mulches to do the job. However, it may be necessary to check if the mulch you are using is suitable for the task in hand. Mulches that are “green”, such as freshly chipped wood, contain a lot of fresh plant material. As this material begins to degrade, it may draw nitrogen from the soil to aid micro-organisms in the composting process. This loss of nitrogen may cause damage to some plants. Fresh plant material may also contain chemicals that inhibit the growth of other plants, or are excessively acidic or corrosive, eg: turpenol in pine chips. These and other problems are solved by buying cured mulch, or leaving mulch to cure for a couple of months, so that natural degradation of the material will render it more benign.