My hybiscus is planted where I have weed cloth and 1 1/2" river stone (light in color) 2" thick. I have heard that the stone may hinder the plants due to heating from the sun. I did not want to use mulch and thought this would work. Plants have been in the ground since Sept. I only notice occassional leaves turning yellow. I do not know the types of hibiscus's I have planted but of the 12 or so half are blooming now.