"Does anyone have any idea what I'm doing wrong?" Paulette, you haven't said what you are doing - how often you water, how near a window facing which direction it is, whether there's air conditioning in the room, or added humidity, etc. etc. Gardenias like the sun, but if your window is facing south and you get intense light all day, plus the plant's actually against the glass, I'd say back it off by a foot or move it to a NW facing window. Gardenias also love cool, moist environments, which means a dry, hot room will not be good for them, but adding a wide humidity tray full of large pebbles and water under the pot will, but never let the water touch the pot, or roots can rot. Keep it as far from the A/C unit as possible if you have one, because they're very drying (even if cooling) - a little fan in the room would be better for air circulation. And unfortunately, this is very common - people who don't understand what keeping bonsai entail give them to other people who don't, and somewhat difficult plants like gardenia don't last long. Certainly trees or bonsai in general can't always wait around til you've taken a course. I'm sure your friend was well-meaning, but don't feel bad because you can't be an instant expert (or even newbie) any more than she/he could. Water when the top of the soil is dry and let it drain, but not sitting in the drain water - your sink is better. Good luck - it may just be readjusting to a new environment and that can take weeks.

Lucy....thank you for the information. I have the bonsai
in my west facing kitchen window. It gets later afternoon
sun. I have a regular gardenia next to it and it is doing
great and blooming indoors. My other alternative is to
put it on my kitchen island which has a skylight directly
over it. Thanks again for the info.

I've had two bonsai gardenias since May -- I'm following directions perfectly, and the blooms are beautiful and the leaves are green, and all of a sudden there are little webs forming, so i think it's mites --what kind of spray can I use to get rid of them? Thanks, Judy

i have seen aphid infestations on gardenias, particularly just below a newly forming bud. pinkish white fuzzy masses. nuke em.