Grounds Maintenance Blog

Landscape management and snow removal tips for commercial properties

Are You Over-Mulching Your Trees?

Posted by Bob Ramser

Mulching Volcano.jpgOver the past couple of decades landscapers have started a trend of over mulching trees. Although a fresh layer of mulch may look nice sometimes, you could actually be over-mulching your trees causing stress and a decrease in vigor.

“Mulch Volcanoes” is the term used when mulch is piled high directly against the trunk of trees, creating a volcano shape. They are very harmful to trees and cause many symptoms of deterioration. Mulching in this manner can even send the tree into irreversible decline.

Problems Associated with Over-Mulching Trees:

Root Suffocation/Root Rot

Deep layers of mulch cause waterlogged soil slowing water loss by preventing evaporation. To breathe, roots must have sufficient oxygen exchange.

Mulching Volcano 1.jpg

Development of Secondary Root System

Roots navigate to the nearest available oxygen and water source. Roots buried under excessive mulch will actually begin to grow up into the mulch rather than down into the soil.  This will cause roots to girdle the trunk, killing the tree.

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Inner Bark (Phloem) Stress

Continuous moisture on the trunk prevents the phloem tissue from proper gas exchange, leading to poor nutrient uptake and eventually death.

Proper Tree Mulching Method

Mulching Volcano 3.jpg
  • Two-four inches (2-4") in depth
  • Keep all mulch three-four inches (3-4") away from the trunk, exposing the root flare zone
  • Mulch to the tree's drip line (outermost circumference of a tree canopy where water drips from and onto the ground), if possible

If a fresh look is desired each season, take some of the old mulch away before adding a new layer. Applying new mulch over old in successive years is the same as applying too deep of a layer all at once. If you have any questions about volcano mulching or tree & shrub health, post your comment below...I'd love to start up a discussion.

Topics: Property Enhancements

Bob Ramser

Written by Bob Ramser

Bob Ramser is the Branch Manager at our North Canton facility. In his role he focuses on customer service, sales in both enhancement and new snow and lawn maintenance contracts, employee retention, quality of the properties, building relationships with employees and customers, and the day to day operations of the branch. Outside of work, he enjoys playing golf, watching sports, being with family, and driving his Roush Mustang.

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