The Right Way to Mulch Around Trees (And the Mistake That Kills Them)

Mulch can be one of the simplest ways to improve the growing environment around a landscape tree. It helps conserve soil moisture, moderates temperature, reduces competition from turf, and protects roots from mower and string-trimmer damage. The problem starts when mulch is piled against the trunk instead of spread over the root zone.

Why Volcano Mulching Causes Problems

Volcano mulching is the familiar mound of mulch stacked high against a tree trunk. It may look neat, but the trunk is not supposed to remain buried in moist organic material. Keeping mulch against bark can create conditions that encourage decay and hide problems at the base of the tree.

Keep the Trunk Flare Visible

A properly planted tree usually widens where the trunk meets the main roots. This area should remain visible rather than disappearing under a mound of mulch. If the trunk looks like a telephone pole going straight into the mulch, pull material back and check where the actual root flare begins.

How Deep Should Mulch Be?

A moderate layer is usually enough. Very deep mulch can restrict air movement into the soil and keep the surface excessively wet. Instead of adding a fresh thick layer every year, check how much old mulch is already present and only add what is needed.

Spread Mulch Wider Instead of Higher

Tree roots extend much farther than the small ring often placed around a trunk. When practical, a wider mulch bed provides more useful root-zone protection than a narrow, deep pile. Even expanding the ring gradually can reduce competition from grass and lower the chance of mower damage.

Wood Chips Can Be a Practical Choice

Arborist wood chips are a useful mulch material because they contain a mix of wood and bark that breaks down over time. Appearance varies more than uniform commercial mulch, but for many tree beds that is not a problem. Whatever material you use, correct placement matters more than creating a decorative mound.