Tree Trunk Rot from Mulch Volcanoes: Keep Mulch Off the Bark

Piling mulch against a tree trunk (“mulch volcano”) holds moisture, causing bark rot and eventual tree death. The flare (where trunk widens to roots) must be visible.

Correct Mulching

• Keep mulch 6–12 inches away from trunk.
• Spread 2–3 inches deep out to drip line.
• Use coarse organic mulch (pine bark, wood chips).
• Never let mulch touch bark.

Ohio’s composted hardwood mulch is especially moisture-retentive—extra caution needed.

Mulch piled against trunk—recipe for rot.

Bark decay from excessive mulch moisture.

Correct mulch ring with gap at trunk.