My hibiscus has few flowers this summer and now for two weeks a white powdery substance on the top branches and bud.

Question

I water whenever leaves wilt.

Answer 1

Here's an article that will help you fix the problem:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-has-white-fungus.htm

https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/hibiscus-fertilizing.htm