Proper Mulching Technique and the Dangers of “VOLCANO MULCH”

volcano mulch
Volcano Mulching

Recently I have been noticing a rash of trees that have become victim to the dangers of “volcano mulching”.  Volcano mulching refers to the piling up of mulch around the base of trees causing moisture to build up around the trunk, rotting out the tree and leading to a slow death by suffocation due to lack of oxygen exchange to the roots.

mulch line
Photograph 2 (Mulch Line)

Proper mulching involves adding a protective layer of organic mulch approximately 2-4 inches thick, keeping the mulch about six inches away from the base of trees so to avoid build up.  Mulch has many advantages including the addition of organic matter to the soil, allowing moisture retention for the plant and helping as a weed barrier to keep weeds down as well as adding an attractive finishing touch to garden beds.

Signs of tree suffocation are indicated by a darkening of the trunk with patches of blacked spots going up the tree.  In Photograph 2 you can see where approximately six inches of mulch had been piled up on this tree causing the tree to already start rotting. When removing the mulch it should be to the level of the tree collar (where the base of the tree starts to flare out). Even routine mulching can gradually build up so it is recommended to remove some of the older mulch if necessary before applying a new fresh layer.  This tree should now be fine since the mulch was removed and the base of the tree will be allowed to heal and the health of the tree restored.

 As Always…Happy Gardening!

 Author:  Lee@Landscape Design By Lee, 2014, All Rights Reserved

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