When mulching trees, it is best to:

• A. Spread a 2-inch layer of coarsely shredded organic mulch over the root ball and out to the drip line of the tree
• B. Mound 4 inches of mulch around the trunk of the tree
• C. Allow grass to grow right up to the base of the tree and do not use mulch
• D. Use marble chips on top of black plastic to block weed growth

Answer: (A)

A proper mulch around a tree forms a shallow, even ring of organic material that protects the root zone without touching the trunk. The best approach is to spread a two-inch layer of coarse organic mulch from just beyond the root ball out to the drip line. This depth helps insulate the soil, conserve moisture, reduce weeds, and improve soil as the mulch decomposes, while still allowing water and air to reach the roots. It’s important to keep mulch away from the trunk, so moisture doesn’t accumulate against the bark and invite rot or pests.

Other methods fail because piling mulch against the trunk creates excess moisture and decay risk, letting grass grow right up to the base deprives roots of water and nutrients and provides little protection, and using marble chips on plastic prevents water and air from reaching the soil and can overheat the roots.