the white stuff could be "white fly".$ V' g4 d& n1 g2 ^0 X% }
I had the same problem before. It because your plant is too wet. I showed the leaves twice a day for a whole week, then the white filies were all gone. 6 n0 M& v6 p( c% a/ e. U0 H, [# bHibiscus is a typical plant, show helps a lot.