My magnolia has never really grown taller, although it has lots of leaves and some flowers in season. We recently realised that there is a large hole (or perhaps the entire trunk is hollow) at the soil-line (see photo). What should we do?
Unfortunately your photo was not attached. I am not sure what has caused the damage to your tree but it is now compromised and will never grow to the full size. I would recommend removing and replacing the damaged tree.