Can someone tell me why my hibiscus bushes do not seem to grow in height? They look healthy green and bloom all the time but do not seem to grow much in size. They are in a spot where they get about 6 to 8 hours of full sun a day. I fertilze them monthly and have mulch in the flower bed they are in. I water the bed weekly or when it looks dry. I do not see any disease or pests on the plants causing damage to the plants. The plants look really healthy. I bought the plants at the nursery this spring and planted them in my bed and have not had any problems with the plants. Can someone please answer this for me?