Does Mulching Help Tree Growth?

Water Conservation

• The roots of young trees need to become established in the soil. A layer of mulch keeps the moisture from evaporating from the soil; the roots are then able to absorb the water. This in turn creates a deeper root system for the tree. As a result, less water is needed when the tree is watered by hand or when using a water irrigation system.

Nutrients

• Mulch decomposes over time, gradually adding natural nutrients to the soil. Decomposing organic mulch supplies the soil with organisms that attract earthworms. Earthworms improve the soil by making tunnels and pulling decomposed mulch deeper into the root system. Although trees benefit from the mulch, some trees might still need supplemental nutrients.

Soil Temperature

• Mulch provides a blanket for the soil, helping to maintain a consistent temperature. As the outside temperature rises or falls, the soil temperature with mulch changes at a gradual rate. A tree that is shocked by a sudden drop in soil temperature might experience stunted growth or, even worse, could die. Maintaining a consistent temperature is important in both winter and summer months.

Weed and Grass Growth

• Trees, grass and weeds are in competition for moisture and nutrients. Placing mulch around the ground stops the spread of weeds and discourages grass from growing. Many weeds have deep roots and grow quickly. Grass roots also grow fast and contain allelopathic chemicals, which are known to slow the growth of tree roots. However, even mulch can't always stop all weeds or grass from growing beneath the cover. Make periodic checks to keep ahead of weed and grass growth and remove as needed.

Other Benefits

• Mulch reduces the loss of soil around the tree by allowing rain or irrigation to enter the soil at a slower pace. The mulch acts a buffer between the water and the soil; the result is less erosion.

  Power mowers and trimmers cause damage to tree trunks. Spreading mulch reduces the need to come in contact with the trunk.