I too am having trouble with my rose of sharon tree. I live in Chicago area and planted the tree a year ago last June (June 2003). First year, some animal damaged the trunk by chewing it pretty good. The tree had tons of blooms but they started to open late August and then just fell off. I have never had not even one flower on my tree yet!
Now, the tree is chock full of buds and I am anxiously awaiting them to open. Its almost a tease, some are so close to opening and others are shut tight. My leaves are green and the tree looks healthy. Other rose of sharons in my area are completely bloomed and have been for about 3 weeks. Mine is planted in the front of my house near the lawn (which was also new last year). It gets watered regularly with the automatic lawn sprinklers about 3 times a week.
I have a sinking feeling its not going to bloom again....its late August here and September cool nights will be upon us soon. Any suggestions as to what I can do next year to encourage blooming buds would be appreciated. Also, with the damaged trunk, will that repair itself over time? The damage is at ground level and my green thumb neighbor put something on it to protect it from further damage. Other than that the tree looks beautiful and healthy, full of buds, but, alas, no flowers
Good luck to you and your rose of sharon. Hope you don't mind me putting my question on your post but I thought maybe the helpful gardeners in here could help us both! Have a great day!