What is “mulch”?

Mulch is simply a layer of surface-covering applied to the soil. Mulch can be wood-chips, bark, gravel, sand, rocks or many other materials. In nature the fallen leaves from plants form mulch naturally under trees and shrubs. Mulch is great habitat for many animals such as lizards and beetles.

Mulch should be applied no thicker than 5 – 10 centimetres.

Why use mulch?
Spreading Mulch

  • prevent weeds growing, reducing maintenance time
  • conserves water by keeping moisture in the soil
  • insulates; keeps soil cooler in summer and warmer in winter
  • prevents erosion; keeps soil from washing away
  • defines garden beds, makes plantings attractive
  • improves soil structure; decomposes and adds to the soil structure
  • reduces the need to mow around individual plants
There are many materials you can use for mulch, depending on your budget & needs.

Bark mulch is attractive, though a somewhat expensive mulch and is available from garden centres and landscape supply companies. Dark in colour, it makes a nice background for ornamental plantings. It can cost anywhere from 45 to 65 dollars a cubic metre, depending on the type of trees used to make it. Pine and Red Gum, are common sources of bark mulch.

Woods chips are often free, from your local park department, an arborist or tree company. They are a bright colour when they are new, but they gradually fade to a more natural grey tone.

All organic mulches will slowly decompose or rot away, whereas sand, gravel and rock mulches will not.

Decomposing organic mulches will improve soil structure but will also remove nitrogen (N) from the soil, possibly leading to nitrogen deficiencies in your plants. This can be overcome by lightly fertilising mulched garden beds once a year with a high nitrogen fertiliser such as chicken manure or ‘blood and bone’.