Roots – Growing How Deep?

Q: A few months back I heard you say that no trees have root systems exceeding eighteen inches in depth. I have heard opposing information that says that our big hardwoods have root systems measured in meters, not inches. Did I hear you incorrectly?

A: There’s no need for a hearing aid, you heard me right. Tree roots are comparatively shallow in our area. They are limited by the dense, undisturbed clay soil that lies under the top eighteen to twenty-four inches of earth. Simply put, tree roots don’t extend where they can’t breathe. To provide anchoring, roots spread outward and occasionally form “sinker roots” that grow downward until they hit oxygen-free clay. Tree roots in sandy soil may be meters deep but this is just a consequence of their extending where the oxygen levels allow them to grow.