Troubleshooting
Southern Canna problems — and how to fix them
Southern Canna (Canna flaccida) 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.
Canna rust
Orange pustules on leaf undersides are caused by Puccinia thaliae. Remove and destroy affected leaves; avoid overhead watering to reduce humidity on foliage.
Leaf roller caterpillars
Caterpillars roll leaves for shelter. Unroll and remove larvae by hand or apply Bacillus thuringiensis when damage is first noticed.
Aphids on flower stems
Dense aphid colonies on emerging spikes weaken flowers. Spray with a strong jet of water or insecticidal soap solution.
Slugs
Particularly active in the moist conditions this canna prefers. Use iron phosphate slug pellets which are safe near water.
Prevent southern canna problems before they start
Most southern canna issues are care-mismatch, not bad luck. Dial in the basics:
Southern Canna problems — FAQ
Why is my southern canna canna rust?
Orange pustules on leaf undersides are caused by Puccinia thaliae. Remove and destroy affected leaves; avoid overhead watering to reduce humidity on foliage.
Why is my southern canna leaf roller caterpillars?
Caterpillars roll leaves for shelter. Unroll and remove larvae by hand or apply Bacillus thuringiensis when damage is first noticed.
Why is my southern canna aphids on flower stems?
Dense aphid colonies on emerging spikes weaken flowers. Spray with a strong jet of water or insecticidal soap solution.
Why is my southern canna slugs?
Particularly active in the moist conditions this canna prefers. Use iron phosphate slug pellets which are safe near water.