Buds

• Rose of Sharon shrubs tend to produce a multitude of buds that sometimes fail to open into flowers. A similar problem involves the shrub that starts flowering normally but later starts to drop buds before they have bloomed. The cause is not clearly understood but is thought to be connected to environmental stress, insects known as thrips that feed on buds and cause them to drop, or a fungal disease known as botrytis.
  
  

Pruning

• Rose of Sharon flowers annually on new growth but develops continually smaller flowers if not pruned. Prune in late winter or early spring to avoid trimming off new growth where buds later develop. Careful pruning in late spring to reduce the number of buds on the shrub causes fewer but larger flowers. To do this, trim back to 2 to 3 buds per stem.
  
  

Pests

• Aphids and whiteflies both prove problematic on Rose of Sharon. Aphids are common insect pests that come in more than 300 species and may be either winged or wingless. They cause curled leaves and excrete a clear, sticky substance that is a telltale sign of infestation. The whitefly is a light-green, winged insect that sucks sap from plants, causing stunted growth, yellowing foliage and leaf drop. Control both insects with insecticides and biological controls such as ladybugs and parasitic wasps.