What depth of mulch around tree trunks is recommended?

• A. 1-2 inches
• B. 2-4 inches
• C. 4-6 inches
• D. 6-8 inches

Answer: (B)

Mulch depth around a tree should be kept moderate to balance moisture, temperature, and airflow for healthier roots. Two to four inches of mulch provides enough coverage to reduce evaporation, moderate soil temperature, and suppress weeds, while still allowing air and water to reach the root zone.

If the mulch is too shallow, it won’t effectively conserve moisture or deter weeds, and the soil can heat up or dry out more quickly. If the mulch is too deep, especially when piled against the trunk, it can keep bark and the base of the trunk too moist, create anaerobic conditions, promote decay, invite pests, and may encourage roots to grow into the mulch instead of the soil. To maximize benefits and minimize problems, keep the mulch in the two-to-four-inch range and maintain a gap between the mulch and the trunk.