I think you're absolutely right & I'd bet the tree would grow around the screws. Also thinking, the bigger the better, tree-wise. Will be interested to see what other people will say about this.
To clarify...the cavity that formed in our mimosa tree wasn't caused by the rod, and to be honest, if the tree hadn't been so messy for the pool we would have done more to try and save it. We do like mimosa trees & we (along with the butterflies & hummingbirds) have really missed the flowers!
