The tree is 25 years old. For many years we pruned religiously every late winter, then noticed we were getting fewer and fewer flowers. The main part of the tree (non-sucker branches) stopped growing, even when we pruned. So we stopped pruning. Now it's an ugly mess and likely no increase in flowering. No suckering occurs from the ground thankfully. For many years, this tree blossomed so profusely it stood out in the landscape from half a mile away.