I also have a problem with a hibiscus tree I just bought from Lowe's. It looked great for a week or two, and then we had a really big rain and the leaves started wilting, and before I knew it, they all fell off and there is nothing left to the tree. I realized the pot that the tree is planted in did not have any drain holes, so we immediately drilled holes in the bottom of the pot, and replaced the soil in case it was mildewed. It has been about 2 weeks since then, and the treee is still not coming back, even though it has gotten plenty of water and sun. I don't think it's completely dead because when I scratch beneath the surface, I see green. I don't know what else to do.