North Queensland gives trees a hard time in a way that a lot of southern advice does not account for. The soil surface bakes hard through the dry, then gets hammered by heavy rain through the wet. Mulch is the buffer for both, and it is close to free.
How deep
Around 75 to 100mm. That is enough to slow evaporation, keep the root zone cool, and suppress most weeds. Much deeper and it starts shedding water rather than letting it through, so the soil under it stays dry while the mulch stays wet, which is the opposite of the point.
How close to the trunk
Not close at all. Pull it back a good hand's width from the trunk. Mulch heaped against bark holds moisture against the collar, and that is exactly the condition that rots it. Volcano mulching, where a neat cone is piled up around the trunk, is a slow way to kill a tree you paid to plant.
Fresh chip versus aged
Fresh chip off a chipper is fine as a surface mulch. It is not a soil conditioner. As it breaks down it pulls nitrogen out of the top layer of soil, so anything with shallow roots planted straight into it will yellow off and sulk. Keep fresh chip on the surface, around established trees and on paths. If you want it in a bed, let it age first.
The free part
If we are doing work on your property, the chip from your tree is yours. Keeping it on site saves us a trip and puts the tree straight back onto your garden. There is no better outcome for a tree that had to come out.
Not sure about a tree on your place? Send a photo. There is no charge for an opinion. Anthony, TreeX
