Gardening resources > Soils and composting > Soils and composting factsheets > Mulches for landscaping > Too much mulch can kill!
Cornell University Department of Horticulture
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Cornell gardening resources Too much mulch can kill!

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  • Mulches for
       landscaping


  • Click photos for larger images.

    Do NOT pile mulch against tree trunks.  (Click for larger view.) Don't mound mulch up against the trunks of trees and shrubs (right). Those volcano-shaped piles may look good to some, but they can kill your trees.

    Instead, spread the mulch about 3 to 4 inches deep in a circle at least 3 feet in diameter around young trees and shrubs. Then brush away mulch at the center of the circle so that it is several inches from the base of the tree.

    A slight depression is OK.  (Click for larger image.) A slight depression in the center is OK (left). Think lunar crater -- not Mt. Vesuvius.

    Even if you keep it away from the trunk, spreading mulch deeper than 4 inches can create shallow, vulnerable root systems. As your trees grow, extend the mulch to their dripline (the edge of the canopy).

    Trees benefit from extensive mulching no more than 3 or 4 inches deep.  (Click for larger image.)Trees benefit more from this kind of extensive mulching (right). You're not doing them any favors by piling it higher and deeper.






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