Sprawling curly black locust and peanutbutter tree

Asked May 12, 2020, 5:03 PM EDT

I am considering putting a metal ring around my trees to stop them from spreading all over the yard. One is a curly black locust and the other a peanut butter tree. My question is how deep would the ring need to be to stop the roots?

Washington County Oregon

1 Response

Tree rings have been suggested as a means to restrain roots where the gardener doesn't want them. They don't always work that way

The fact is that they should be placed at the dripline (ends of the branches) or just beyond. And the barrier should extend 3 feet into the soil with a 4-inch lip above ground.

Doing all that only buys you time. Within several years the roots will reach the barrier then will either climb the lip and dash for freedom, or will begin to circle just inside the barrier.

Circling roots such as those are poor stabilizers for the tree. It's very likely the tree and its pancake of roots will topple years later.