The azalea japonica under my 15 foot tall acer palmatum has not flowered for two seasons. Prior to that, there were plenty of small white blossoms. The azalea gets only a couple of hours of direct sun and some dappled sun during the day. Perhaps less sun now than in previous years due to the growing tree. What could be another reason why it isn't flowering?
Sequence of events could implicate the tree, if not change in exposure maybe increased root competition. On the one hand evergreen azaleas are often so prolific it would seem that a really severe problem would have to occur to prevent all flowering - even closely sheared specimens in traditional Japanese gardens manage to flower beneath the part that is sheared. On the other hand I myself have seen not a few specimens here that were flowering poorly or not at all. Think about your cultural practices in the last two years to see if there might have been some kind of change in situation that caused the shrub to go blank. Heavy pruning? Mulch piled over the crown?
No heavy pruning or mulching. I did have dutch iris bulbs planted next to the azalea a few years ago. I dug those up to move them to another place a couple of years ago. Maybe the roots of the azalea got disturbed. Would this cause the plant not to flower?