Troubleshooting
Dahlia problems — and how to fix them
Dahlia (Dahlia pinnata) 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.
Slugs on young growth
Slug barriers at emergence; established plants outgrow them.
Earwigs in flowers
Trap with rolled corrugated cardboard or inverted pots stuffed with straw.
Blind shoots
Pinch out the central growing tip at 30 cm to encourage branching and flowering.
Tubers rotting in storage
Lift after first frost, cure for a week, store in dry vermiculite at 5-10°C.
Powdery mildew
Common in late summer; remove affected leaves and improve airflow.
Prevent dahlia problems before they start
Most dahlia issues are care-mismatch, not bad luck. Dial in the basics:
Dahlia problems — FAQ
Why is my dahlia slugs on young growth?
Slug barriers at emergence; established plants outgrow them.
Why is my dahlia earwigs in flowers?
Trap with rolled corrugated cardboard or inverted pots stuffed with straw.
Why is my dahlia blind shoots?
Pinch out the central growing tip at 30 cm to encourage branching and flowering.
Why is my dahlia tubers rotting in storage?
Lift after first frost, cure for a week, store in dry vermiculite at 5-10°C.
Why is my dahlia powdery mildew?
Common in late summer; remove affected leaves and improve airflow.