Small flowers on African violets
Thank you for your question. The two plant care issues you don’t mention are fertilization and humidity, both of which are identified as important to plant health in the following article: http://extension.uga.edu/publications/detail.html?number=C660&title=Growing%20African%20Violets Your plants appear healthy; perhaps they haven’t gotten adequate potassium, critical to flower development. Hope this is helpful. Good luck!