Since my expertise is in growing bougainvillea in containers and not in the landscape, the information I provide is centered around growing in pots, baskets and other type containers. Bougainvillea Bloom Season in North America Bougainvilleas' natural habitat is equatorial where day and night lengths are almost equal. In winter, blooming is better than in the dog days of August because of night length. Also, some cultivars are triggered to bloom after a rainy season followed by a dry season. Best Climate for Bougainvillea Bougainvilleas are tropical and must be protected from frost .
Bougainvilleas thrive in full sun .
At least 5 hours a day of full sunlight is the minimal light required for good bloom. More hours of direct sun is better. Less than 5 hours and the plant may not bloom very well. In shade or partial shade, you will have nice vegetative growth, but little or no bloom. A Bougainvillea just doesn't bloom well indoors.