Much like people, garden mulch can be found in a variety of different shapes, sizes and colours, so how do we know which mulch is best to use, particularly in relation to the long term health of our trees?

Generally speaking, mulches can be divided into two main categories, being organic and non-organic, and whilst both have benefits specific to their type, there are a number of general positive benefits which all mulches, regardless of their type or origin can provide, so let’s look at those as a starting point.

  • Mulches placed over the soil can provide a uniform and aesthetically pleasing look to garden beds, and can be used to formalise designated areas, particularly around existing trees.
  • When spread thickly, between 75 to 100 mm in depth, mulches suppress weed growth, and when considering tree health can reduce competition, particularly from grasses and lawn which may be present over the root zones of trees.
  • Mulches act as an insulator, moderating soil temperature. This provides a more constant growing environment which is beneficial to tree growth and general tree health. By eliminating extremes of temperature, stress to shallow rooted trees and plants can be minimised.
  • Mulches help to retain moisture within the soil profile by reducing evaporation, which assists in maintaining more constant soil moisture levels, again being generally beneficial for the growth of trees.
  • Mulches can be used to reduce compaction in the soil profile by spreading loads and distributing weight resulting from pedestrian and/or vehicular traffic.
  • In certain circumstances, mulches can be used to control and minimise soil erosion.

So regardless of the type of mulch we have used, all of the above points can be easily achieved, and all assist in improving the environment in which our trees are growing. We can therefore make decisions based simply on the size, shape, colour and type (organic/non-organic) of mulch, and be confident that we are improving the general health and growing environment of our trees.


About the author: Dave is a qualified, experienced and passionate arborist working with the awesome team at Brisbane Tree Experts. “We care about your trees living”. And we hate seeing piles of grass clippings around the stems of trees!