Hibiscus is in a sunny spot but daily yellow leaves on each tree with no insects. Water trees daily. Trees do not seem to grow but flowers are profuse.
Yellow Leaves on Hibiscus Plants
Certified GKH Gardening Expert
There are several reasons this can happen, though its sounds like you could be giving the plant too much water. This article explains many of them and will help you decide which is likely for your plant: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/answers-to-what-causes-hibiscus-leaves-turning-yellow.htm