More blooms on a Gardenia?

I was just wondering if someone could tell me what makes a gardenia bloom more often. Mine seems to just have one at a time as a rule, the minute one is brown and falls off, another one blooms. My boyfriend's mother has one just a little bit larger than mine and it is full of them. Does this depend on climate? Sun? or just depending on the plant?More blooms on a Gardenia?
I have found that my gardenias do not bloom if they are in full sun. Once I moved them to partial shade, they started blooming like crazy!More blooms on a Gardenia?
Do you fertilizer yours? Your boyfriend's mother probably does