The Q&A Archives: Rose of Sharon

Question: The house we moved into more than a year ago has a Rose of Sharon bush that was probably planted after the house was built, more than 30 years ago. It bloomed last year, but this year the buds don't fully open and they look "sticky", then they drop on the ground. Also, there are only a few buds. Would pruning help or is it too old?

Answer: Rose of Sharon (Hibiscus syriacus Althaea) should be pruned annually to keep it in shape and to promote flowering. Generally the previous season's growth is cut back to two buds. If your plant has never been pruned, and you want to rehabilitate it, plan to spend three years doing it. If you cut it back too drastically all it once, it might not recover. Begin by removing dead or dying branches and leafless twigs. Then cut all of the remaining branches back, leaving two buds on each. Then reach way into the shrub and carefully choose branches to remove, cutting some of them all the way back to the main stem, and others only part way. Try not to remove more than one-third of the plant in any one season. Next year you can cut another third out and the following year, the remaining third. If the flowers are sticky, the plant may have aphids. These sucking insects distort leaves and damage flowers in a hurry. They also leave behind a sticky residue called honeydew. Sometimes sooty mold grows on the sugar the honeydew contains and makes plants look unattractive. If your plant has aphids, hose them off with a strong stream of water. Be sure to direct the spray on the undersides of the leaves and on the stems, too, to dislodge any eggs.

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