Is it a Tropical Hibiscus, Hibiscus rosasinensis or one of the Hardy Hibiscus, Hibiscus moscheutos or one of the many others?

Since you're growing it in a container, the variety may not matter. Mine get yellow leaves\drop buds during extremely dry conditions or extremely wet.

You'll find some good info at the link below.

Here is a link that might be useful: How To Care For Hibiscus Plants

how often do you water? i have to water mine every 2 days or it'll drop buds.

i use regular miracle gro.

Thank you for the information. I don't know the variety of the plant but the link to the article was a great help. Also, you both made me realize that I am not watering nearly enough. Thanks for all your help!

Glad I checked these posts first. I've been having this problem as well with my Montego Wind Hibiscus. My daughter picked it out for daddy for Father's day two years ago and we are trying very hard to keep it healthy. I thought we were watering enough but I guess not. It grows beautifully and has bloomed a lot up til this summer. We keep it inside in a sunny window, it's grown very tall with large healthy looking leaves but every time a bud starts it grows about an inch then turns yellow and falls off. I'm going to get some houseplant fertilizer today and see how that turns out in the next few weeks.
Or maybe it's just lonely. He's been the only plant we've had for the last two years but I'm hoping to change that, lol. That's why I'm here for some research.