Wow! That doesn't sound good. It sounds like you have a root problem. Either a pest or too much watering, maybe even too root-bound. The odd thing is that usually the flowers are the first to drop whenever there's an issue, wheather it's pests, root problems, or lighting issues. It sounds like it's in survival mode! It's on its way out so it puts all its energy into reproducing!
First things first: Look for pests that are attached to the leaves... spider mites might very well be the culprit here so, look for little spiderwebs. Aphids usually attack the new growth and flowers first, but you can check for those too. If you find any pests I would suggest going for the big guns right off the bat and use a pesticide. No time for usuing more natural and less toxic methods of mild soap rinses.
Next: check the roots and the soil. If you can't get your finger into the soil it's time to repot. If it's soggy, it's time to stop watering until it's dried out. In fact, if the soil is soggy, you should first make sure you have the plant potted in a pot that has decent and unobstructed drain holes... then repot it to help it dry out more quickly... normally you wouldn't have to do that, but your plant sounds very stressed and needs all the help it can get. While repotting and checking the soil, check for soil pests such as grubs. The little black flies usually don't hurt, but if they're overpopulated and infested they can damage the roots. Agian, the remedy I'd suggest is a pesticide for such creatures because there's no time to lose. There is one other possibility, but it's rare because the plant usually lets you know way ahead of time what it needs, but if you water it too little the plant will rebel. Usually, when it needs water it doesn't just drop its leaves but it droops and looks dried out. So, I doubt it's that unless its been a chronic condition. But, again, the flowers usually go first in that situation.
After you've treated your plant place it in a non-drafty window, with lots of sun, and keep it warm.
I hope I've been of some help. Good luck!

Hi,
I bought hisbiscus this year. I potted into terracota containers and kept near north-west balcony where it gets sun in the early morning and late afternoon. I didnt use really any fertilizer but good organic soil mix I used. it did so well that in a month I had good bloom and good green leaves. suddenly I felt the container is small so transferred to big plastic container for the first time. put E B Stone's rose and flower food.
but within a week all leaves are tunring yellow all over.
what could be the reason?
is it,
1)plastic container?
2) over -water
3) under water?
4) missing nutrients?
5) transplanting shock?(I re-potted from nursery pot to my big size plastic container)

please help! I prefer only organic stuff so any organic stuff would be good. miracle gro is big sh*** of chemical.