Troubleshooting
Dahlia 'Bishop of Oxford' problems — and how to fix them
Dahlia 'Bishop of Oxford' (Dahlia 'Bishop of Oxford') 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 coating on leaves is very common in warm, dry conditions. Improve air circulation; treat with potassium bicarbonate or a fungicide spray.
Aphids
Cluster on new shoots; dahlias are particularly susceptible. Treat with insecticidal soap; check regularly as aphids spread viruses.
Earwigs
Feed on petals and foliage at night. Set earwig traps (inverted pots filled with straw) around plants.
Tuber rot
Caused by waterlogging or storage in damp conditions. Store tubers in barely moist peat or coir; inspect regularly through winter.
Slugs and snails
Attack young shoots in spring as they emerge. Use iron phosphate pellets around the planting area.
Prevent dahlia 'bishop of oxford' problems before they start
Most dahlia 'bishop of oxford' issues are care-mismatch, not bad luck. Dial in the basics:
Dahlia 'Bishop of Oxford' problems — FAQ
Why is my dahlia 'bishop of oxford' powdery mildew?
White powdery coating on leaves is very common in warm, dry conditions. Improve air circulation; treat with potassium bicarbonate or a fungicide spray.
Why is my dahlia 'bishop of oxford' aphids?
Cluster on new shoots; dahlias are particularly susceptible. Treat with insecticidal soap; check regularly as aphids spread viruses.
Why is my dahlia 'bishop of oxford' earwigs?
Feed on petals and foliage at night. Set earwig traps (inverted pots filled with straw) around plants.
Why is my dahlia 'bishop of oxford' tuber rot?
Caused by waterlogging or storage in damp conditions. Store tubers in barely moist peat or coir; inspect regularly through winter.
Why is my dahlia 'bishop of oxford' slugs and snails?
Attack young shoots in spring as they emerge. Use iron phosphate pellets around the planting area.