The next time you find yourself walking in a forest, look down. You are not walking on bare ground, you are walking on years of mulch that protect and nourish the root systems of trees. In our landscapes, we often remove this layer of debris. The result is the tree in our yard has to contend with compacted soils, mower and weed eater strikes, and higher evaporation rates.

What is Mulch?

Any material used to cover soil is known as mulch. The best mulch for use around trees is organic mulch such as bark, wood chips, lawn clippings, or leaves. Organic mulches add nutrients to the soil as they decompose. Inorganic mulches, such as rock, gravel, or decomposed granite, do not contribute to soil nutrition but they do protect the soil and roots, keep weeds down, and help hold soil moisture.

How Do I Apply Mulch?

Trees situated in turf areas benefit greatly from mulch because the mulch serves as a buffer, keeping weed eaters and lawn mowers from striking and damaging the trunk. Mulch can also create a cleaner-looking landscape.

Ideally mulch should cover the entire root zone of the tree. Wider is always better! Be careful not to pile mulch directly against the trunk as it can suffocate the tree. Install mulch about 4 to 8 inches away from the trunk.

Trees require twice the amount of water that turf does so a drip system can be installed under the mulch for proper irrigation. Installing edging between turf and mulch will help keep the mulch in place and prevent grass from encroaching.

How Do I Maintain My Mulch?

Over time, wood mulches will decompose, losing color and volume. Maintain mulch by adding a thin layer of fresh material for appearance.

Inorganic mulches require less maintenance. Use pre-emergent herbicides to prevent weed seeds that have landed in the mulch. Blowers can be used to remove leaves.

Read about proper mulching techniques from the International Society for Arboriculture.