Check the FAQ, which has some excellent posts on gardenias.

You have found, like many before you, that gardenias can be more tempermental than a strong-willed, cranky 2 year-old (I know, I've got both) when it comes to reflowering. However, somewhat like toddlers, it's possible to grow out of the cranky stage by figuring out what the plant really needs and responding accordingly. Good luck!

Jim

Hi jasmine 123, One thing that I've found to help prevent budds dropping from gardenias is to keep them cool, especially at night. By cool I don't mean cold, but somewhere between 50 and 65. Hope yours does well. Jerry

Most flower once a year, and I assume by your question its been longer than that since it bloomed. Mine that live outdoors bloom in late spring, but that can vary with the cultivar. I wonder if some types need a relative cooling period to set buds. Maybe there's not enough temperature variation? Others could answer better. If you look at the reasons why things go wrong with gardenias, it seems to me that the causes are so diverse, its hard to pin a specific cause down. Too little water, too much, too much heat, not enough, etc., etc. Still a great plant, and well worth the effort.

Thank you all for the suggestions!

JimShy, how do I get to the FAQ section? I just bought 2 gardenias today and need to learn how to care for them. Thanks!
Judith

I keep 2 types of Gardenias in a south window in winter. The room is kept quite cool to cold, especially at night. In summer, it's placed outdoors, and gets a monthly feeding w/acidic fertilizer.
Because I live in IL and winter's can be dry, aside from a humidifer and 2 indoor fountains running, I take plant to sink/shower and hose/spray away. They're also misted daily. I allow soil to dry a bit in winter. I never prune tree or plant..too scared I'm going to cut bud stems. Toni

My gardenia, too, had blooming problem. I used to plant it in a 5 gallon pot, took extra care, yes, it bloomed, but not much. Until I saw my neighbor's, it bloomed like crazy every year. My neighbor has no idea, in fact, she never bother to take care of it. Here is what I observe, it is planted is nearly clay, top soil is very very dry; it is planted right beside a ditch, roots probably get lot of water; part shade, almost no afternoon sun. I planted mine in the similar spot last November (There was no winter last year, it was almost 90 F in Louisiana in early November.) Hopefully mine will be great this year.