This same thing happened to my Rose of Sharon shrubs this year. A lot of buds, very few opened. It seems that the insecticide on the buds would also affect the flowers and then the bees, butterflies and hummingbirds that gather nectar from the blooms would be poisoned. Also, the leaves on a few of mine are turning yellow. Are they dying?

Has anyone found anything to work on this problem? I have exactly the same problem as r VorBroker and Ms Rowan. TN extension service has not a clue. My brown buds are still attached. Bush is fine. I hate to loose all my Rose of Sharons. Disease eventually spread to all 9 of my bushes by the end of the year last year. They are now dormant at 22 degrees outside. Thank you for your attention.

Bud drop can be caused by too much or too little soil moisture, and as Mr. Stack mentioned the disease we know as Botrytis, which we can treat. As noted in your description of the problem a disease will spread from one plant to the next all the way down the row, versus an environmental cause which would affect all the plants at the same time. Fungicides are only preventative and must be applied before the disease develops. In Illinois, fungicides currently label are products such as Captan, copper sulfate, chlorothalonil. Read the labels at your local garden center to be sure both the disease and plant are on the label before purchasing.