Why Rose of Sharon Buds Won’t Open: Botrytis Blight

If one Rose of Sharon blooms beautifully while another forms buds that rot and fail to open, the culprit is likely Botrytis cinerea (gray mold).

Symptoms

• Buds turn brown, mushy, and fail to open.
• May see fuzzy gray spores in humid weather.
• Healthy-looking buds on the same plant may be infected inside.

Treatment

1. Remove ALL buds from the affected shrub—healthy and diseased.
2. Bag and trash them (do not compost).
3. Spray the entire shrub with a foliar fungicide labeled for ornamental shrubs (e.g., chlorothalonil, copper).
4. Repeat per label (usually 7–14 days).

Prevention

• Improve air circulation: prune crowded branches.
• Avoid overhead watering; water at base.
• Limit nitrogen fertilizer—excess promotes soft, susceptible growth.
• Clean up fallen debris in fall.

The nearby healthy shrub may escape infection if treated promptly. Monitor closely.