Oak Trees – Adding Dirt

Q: I am thinking of adding dirt to my lawn under several mature oak trees in two tiers. Will adding 2-3 feet of dirt around the base of these trees hurt them?

A: I don’t mean this to be unkind, but let’s try an experiment: Take a towel from the bathroom and wrap your head with it. Is breathing easy? Probably not.

My point is this: tree roots breathe in the soil. They “exhale” harmful gases and they “inhale” oxygen, just like we do. Adding 6″ of porous topsoil wouldn’t be a big problem but adding 2′ – 3′ would be a tree killer. In addition, putting dirt up against the tree trunk would make a great spot for fungi and bacteria to start decomposing the bark, allowing termites into the tree interior. Rethink your plans to see if you can accomplish something attractive without damaging the tree roots.