Are you fertilizing them? I don't fertilize mine and they just stopped blooming because of non-stop rain and clouds.
Too much fertilizer will produce lovely green foliage in abundance, but may keep them from blooming. Our maybe the fertilizer should be changed to one that promotes blooms, would have a higher potassium ratio in the three things listed.
NPK
N: nitrogen promotes foliage growth
P: phosphorous promotes root growth
K: potassium promotes blooms
