the white stuff could be "white fly".2 L1 W# T* P9 g. F+ X, ^- D/ d
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." M6 b% L! B9 R8 c( G6 \6 E
Hibiscus is a typical plant, show helps a lot.