ATLANTIC HIGHLANDS, NJ- Summer is such a wonderful time for working in our yards.  A typical sign of the season is the appearance of those mulch ‘volcanoes’ that decoratively surround the trunks of trees. If you are one of those who have thus adorned your trees, the Atlantic Highlands Shade Tree Commission has some advice for you – STOP!!  Those ‘volcanoes’ are killing your trees!  They are also wasting money on excess mulch material. 

Mulch should never be piled into a cone around the tree trunk.  In fact, mulch should not touch the trunk at all!  Mice, insects, and fungus may hide next to the trunk and feed on parts of the tree.  The cone-shaped mulch piles and thick layers of mulch also prevent water from reaching a tree’s roots.  Tree roots that grow up into the cone mulch on top of the soil cannot be healthy.  Never use plastic sheets under the mulch; plastic sheets block the passage of air and water and also stunt root growth. 

The Shade Tree Commission has some more words of advice:


Proper mulching, conversely, adds to the life and health of your trees:

  • Mulch helps the soil hold water for the tree roots. 
  • It adds organic matter to the soil as it gradually breaks down, thus acting like a slow-release fertilizer. 
  • Mulch helps to prevent the soil washing away.  Soil erosion not only stresses the tree, but also can increase the chance of a blow-down in a storm. 
  • Mulch helps moderate soil temperatures.  It behaves like an insulating blanket in all seasons; this is much less stressful for the tree’s roots.
  • Mulch helps reduce weeds and grasses around trees.

What do the experts say?

  • Keep mulch away from tree trunks!
  • Trees mulched in groups grow better than trees mulched alone.
  • Put the mulch on the soil surface and do NOT mix it into the soil.  Let the mulch decay naturally.
  • Mulch helps young trees survive.
  • For newly planted trees, mulch out to 1 foot beyond the root ball.
  • Mulch that is kept away from the trunk and is at least 2 to 4 inches thick lets the tree get ready for winter. 

Best Materials for Mulch for Trees:

  • Bark chunks or shredded bark that is at least 3/8” in size.  Pine bark will last better than hardwood bark
  • Pine needles
  • One-year-old wood chips
  • Leaves that were shredded and composted for at least 3 months.

Worst Materials for Mulch for Trees:

Fresh grass clippings, fresh organic mulch, peat moss or sawdust, ground-up rubber tires, pebbles, rocks, or cobblestones.

To mulch trees the proper way, mulch in a donut shape by starting 6 inches from the tree trunk at ground level and mulching outward to the edge of the dripline to a maximum depth of 2 to 4 inches.  Never let the mulch touch the base of the tree!


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Allan Dean

Allan Dean is editor, publisher, and founder of the Atlantic Highlands Herald. Published since 1999 and selected in 2000 by the Borough of Atlantic Highlands as one of their official newspapers, making...