Troubleshooting
Tuberous Begonia problems — and how to fix them
Tuberous Begonia (Begonia × tuberhybrida) 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 dusty coating on leaves from poor airflow and humid, crowded conditions. Space plants, water at the base, avoid wetting foliage, and remove affected leaves; treat persistent cases with an appropriate fungicide.
Bud drop
Flower buds dropping before opening usually signals heat stress, erratic watering, or low humidity. Provide afternoon shade, keep moisture even, and shelter from drying wind.
Tuber rot
The fleshy tuber rots in cold, wet soil or in storage. Ensure sharp drainage, never overwater, and store cleaned dormant tubers dry and frost-free over winter.
Botrytis (grey mould)
Fuzzy grey rot on stems and flowers in cool, damp, stagnant air. Improve ventilation, remove spent blooms and dead material promptly, and avoid overhead watering.
Prevent tuberous begonia problems before they start
Most tuberous begonia issues are care-mismatch, not bad luck. Dial in the basics:
Looking for tuberous begonia in general rather than its problems? Read the full tuberous begonia care guide — light, water, soil and feeding.
Tuberous Begonia problems — FAQ
Why is my tuberous begonia powdery mildew?
White dusty coating on leaves from poor airflow and humid, crowded conditions. Space plants, water at the base, avoid wetting foliage, and remove affected leaves; treat persistent cases with an appropriate fungicide.
Why is my tuberous begonia bud drop?
Flower buds dropping before opening usually signals heat stress, erratic watering, or low humidity. Provide afternoon shade, keep moisture even, and shelter from drying wind.
Why is my tuberous begonia tuber rot?
The fleshy tuber rots in cold, wet soil or in storage. Ensure sharp drainage, never overwater, and store cleaned dormant tubers dry and frost-free over winter.
Why is my tuberous begonia botrytis (grey mould)?
Fuzzy grey rot on stems and flowers in cool, damp, stagnant air. Improve ventilation, remove spent blooms and dead material promptly, and avoid overhead watering.