Troubleshooting
Cathedral Begonia problems — and how to fix them
Cathedral Begonia (Begonia 'Cathedral') 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.
Rhizome rot
Overwatering or water sitting on the crown causes rapid rotting; switch to bottom-watering and ensure the compost dries slightly between sessions.
Powdery mildew
Common on rhizomatous begonias in humid but poorly ventilated rooms; increase airflow and remove affected leaves at the first sign of white coating.
Failure to flower
Insufficient light or keeping temperatures too warm year-round can prevent the late-winter bloom flush; a slightly cooler rest period (16-18°C) in autumn encourages bud set.
Prevent cathedral begonia problems before they start
Most cathedral begonia issues are care-mismatch, not bad luck. Dial in the basics:
Cathedral Begonia problems — FAQ
Why is my cathedral begonia rhizome rot?
Overwatering or water sitting on the crown causes rapid rotting; switch to bottom-watering and ensure the compost dries slightly between sessions.
Why is my cathedral begonia powdery mildew?
Common on rhizomatous begonias in humid but poorly ventilated rooms; increase airflow and remove affected leaves at the first sign of white coating.
Why is my cathedral begonia failure to flower?
Insufficient light or keeping temperatures too warm year-round can prevent the late-winter bloom flush; a slightly cooler rest period (16-18°C) in autumn encourages bud set.