a couple of years ago my lilac bush was cut very short. ever since then it has never bloomed again. what can I do?
Pruning lilac almost to the ground is a time-honored technic for rejuvenating an overgrown bush. If your shrub is in mostly sun and you fertilize it, it will recover. In early spring before it leafs out, remove spindly, weak growth (less than pencil size) if the base of the shrub is cluttered. That helps get sun and air to the interior of the plant.