Troubleshooting
Rex Begonia problems — and how to fix them
Rex Begonia (Begonia rex-cultorum) 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
White powdery patches on leaves are the classic rex begonia complaint, driven by stagnant, humid air. Improve airflow, water at the base, avoid wetting foliage, and remove affected leaves promptly.
Crispy brown leaf edges
Usually humidity too low or salt buildup. Raise ambient humidity, keep away from heating vents, and flush the soil to clear accumulated fertiliser salts.
Rhizome and root rot
Mushy, blackened rhizome from overwatering or a soggy mix. Let the surface dry between waterings, use a shallow well-draining pot, and never bury the rhizome too deeply.
Winter leaf drop / dormancy
Many cultivars naturally drop leaves and rest in low light and cool temperatures. Reduce watering, hold off feeding, and keep the rhizome barely moist until new growth reappears in spring.
Prevent rex begonia problems before they start
Most rex begonia issues are care-mismatch, not bad luck. Dial in the basics:
Rex Begonia problems — FAQ
Why is my rex begonia powdery mildew?
White powdery patches on leaves are the classic rex begonia complaint, driven by stagnant, humid air. Improve airflow, water at the base, avoid wetting foliage, and remove affected leaves promptly.
Why is my rex begonia crispy brown leaf edges?
Usually humidity too low or salt buildup. Raise ambient humidity, keep away from heating vents, and flush the soil to clear accumulated fertiliser salts.
Why is my rex begonia rhizome and root rot?
Mushy, blackened rhizome from overwatering or a soggy mix. Let the surface dry between waterings, use a shallow well-draining pot, and never bury the rhizome too deeply.
Why is my rex begonia winter leaf drop / dormancy?
Many cultivars naturally drop leaves and rest in low light and cool temperatures. Reduce watering, hold off feeding, and keep the rhizome barely moist until new growth reappears in spring.