I don't understand what triggers blooms. The bougainvillea I'm growing is very sporadic about blooming. Currently it is putting out lots of new growth which is good, but very few blooms. It bloomed well earlier. Last year blooms followed a dose of fertilizer. This year it has responded to that with new growth. The ones at the garden center in town seem to have perpetual bloom for the most part, but they aren't sure why. They think it is due to fertilizer maybe. I'm finding it needs a lot of water or it will drop the leaves.
