Troubleshooting
Begonia problems — and how to fix them
Begonia (Begonia × hortensis) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
Improve air flow; treat with fungicidal soap.
Yellow lower leaves
Overwatering or root-bound.
Few flowers
Too much shade or under-feeding.
Soft black stem base
Botrytis rot; remove and improve air flow.
Wilting in heat
Hot afternoon sun; move to part shade.
Prevent begonia problems before they start
Most begonia issues are care-mismatch, not bad luck. Dial in the basics:
Begonia problems — FAQ
Why is my begonia powdery mildew?
Improve air flow; treat with fungicidal soap.
Why is my begonia yellow lower leaves?
Overwatering or root-bound.
Why is my begonia few flowers?
Too much shade or under-feeding.
Why is my begonia soft black stem base?
Botrytis rot; remove and improve air flow.
Why is my begonia wilting in heat?
Hot afternoon sun; move to part shade.