Answer: It does sound perplexing, but bougainvilleas can refuse to bloom for almost any reason. The fact that they look healthy is good - that means they have the potential to bloom. Sometimes they just need more time to mature and sometimes they need a little encouragement. Bouganivilleas bloom on new shoots so pruning the reluctant one back a little will encourage new shoots, which will hopefull bloom. If this doesn't work, try a little root pruning (sever some of the roots by setting the blade of your spade on the ground 8-10 inches away from the main stem of the plant and stepping down so the spade goes straight into the soil its full depth). Root pruning usually shocks a bougainvillea into waking up and producing blooms.
Hope these suggestions help!
Q&A Library Searching Tips