Your profile doesn't say where you live. That could be a big factor. Not knowing any specifics, I'm making the following SWAG, Scientific Wild A**ed Guess. First, I'm guessing it is a perennial hibiscus since it come back each year. Buy a good slow release fertilizer, one of the pelletized types. Work the soil around the roots. Water often so the fertilizer is released with each watering. In early spring, take a black plastic garbage bag and cut a hole in the center. The hole is to allow the stems and trunks to be uncovered. Place the bag around the plant and put a brick on each corner, This will help heat the soil and cause the hib to sprout earlier. You will get more growing time. Water and fertilize.

I have some what the same problem, I trimed my tree type before last winter and kept them inside and they came back nice and full. However they have no buds yet. Gave them a good fertilizer. today 7-18-06 Nutten yet!