Answer: Bougainvilleas have a bloom, growth and resting cycle which they repeat several times a year, depending upon weather. They like it hot and will bloom most frequently when the weather is sunny and hot. Typically the cycle is 6-8 weeks. They will develop new stems and leaves, then flower, then rest. When they are finished resting they will grow and bloom again. I'd withhold fertilizer and water the plants deeply only once a week. As long as the weather cooperates they should fall into the right cycle. You can prune them back to encourage new (and hopefully flowering) shoots and stems.
Best wishes with your bougainvillea!
Q&A Library Searching Tips