the white stuff could be "white fly"., R# Z8 y* h0 }5 w$ k8 u; o, f% V
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.' o8 O. x4 ^& G. A
Hibiscus is a typical plant, show helps a lot.