Troubleshooting
Dahlia 'Mystery Day' problems — and how to fix them
Dahlia 'Mystery Day' (Dahlia 'Mystery Day') 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 coating on leaves in dry, warm spells; treat early with a potassium bicarbonate spray and improve spacing.
Aphids
Cluster on soft stem tips; remove manually or spray with insecticidal soap solution.
Earwigs
Damage spiky petals overnight; use overnight traps made from rolled newspaper filled with dry straw.
Tuber rot
Lifted tubers must be dried and stored correctly in cool, frost-free conditions with good air circulation.
Staking failure
Tall stems are wind-susceptible; stake plants when 30 cm tall using bamboo canes and soft ties.
Prevent dahlia 'mystery day' problems before they start
Most dahlia 'mystery day' issues are care-mismatch, not bad luck. Dial in the basics:
Dahlia 'Mystery Day' problems — FAQ
Why is my dahlia 'mystery day' powdery mildew?
White coating on leaves in dry, warm spells; treat early with a potassium bicarbonate spray and improve spacing.
Why is my dahlia 'mystery day' aphids?
Cluster on soft stem tips; remove manually or spray with insecticidal soap solution.
Why is my dahlia 'mystery day' earwigs?
Damage spiky petals overnight; use overnight traps made from rolled newspaper filled with dry straw.
Why is my dahlia 'mystery day' tuber rot?
Lifted tubers must be dried and stored correctly in cool, frost-free conditions with good air circulation.
Why is my dahlia 'mystery day' staking failure?
Tall stems are wind-susceptible; stake plants when 30 cm tall using bamboo canes and soft ties.