My kitty used to do this to a tree that I had. Go to your local hardware store and ask for hardware cloth. It's 1/2" wire mesh. Measure the inner diameter of the pot and cut a circle out of the hardware cloth to fit. Cut a straight line from the outside of the circle to the middle and cut another circle a little bigger than the diameter of the trunk of your tree. You might have to twist & wiggle it a little to get it in the post, but it will keep your baby from digging and you can water through the mesh. It worked for us!
