How much mulch is too much?

How much mulch is too much is often asked.
Mulch is marvelous but it can cause collar rot if it is too close to the trunk of hte tree or plant.
Keep a distance of at least 25 cms from the trunk of a tree.
The larger the trunk, the greater the distance. A mulch free zone equal to half the width of the tree trunk is a good guide.

Mulch which is too deep, can stop rain from seeping through!

Mulch should be no deeper than 10cms.