Troubleshooting
Canna 'Red King Humbert' problems — and how to fix them
Canna 'Red King Humbert' (Canna 'Red King Humbert') 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 leaf roller
Caterpillar larvae roll leaves and feed inside. Remove manually or apply Bacillus thuringiensis where infestations are severe.
Spider mites
Hot, dry conditions encourage spider mite colonies on the underside of leaves. Increase humidity and wash foliage to dislodge mites.
Frost damage / overwintering
Not frost hardy. Lift rhizomes after the first autumn frost and store in barely moist compost in a frost-free location over winter.
Viral mosaic
Mosaic-patterned, distorted leaves indicate canna virus. Remove and destroy affected plants; buy from virus-indexed suppliers.
Bacterial rot on rhizomes
Damaged or wet rhizomes in storage can develop bacterial rot. Inspect stored rhizomes regularly over winter and remove affected portions.
Prevent canna 'red king humbert' problems before they start
Most canna 'red king humbert' issues are care-mismatch, not bad luck. Dial in the basics:
Canna 'Red King Humbert' problems — FAQ
Why is my canna 'red king humbert' canna leaf roller?
Caterpillar larvae roll leaves and feed inside. Remove manually or apply Bacillus thuringiensis where infestations are severe.
Why is my canna 'red king humbert' spider mites?
Hot, dry conditions encourage spider mite colonies on the underside of leaves. Increase humidity and wash foliage to dislodge mites.
Why is my canna 'red king humbert' frost damage / overwintering?
Not frost hardy. Lift rhizomes after the first autumn frost and store in barely moist compost in a frost-free location over winter.
Why is my canna 'red king humbert' viral mosaic?
Mosaic-patterned, distorted leaves indicate canna virus. Remove and destroy affected plants; buy from virus-indexed suppliers.
Why is my canna 'red king humbert' bacterial rot on rhizomes?
Damaged or wet rhizomes in storage can develop bacterial rot. Inspect stored rhizomes regularly over winter and remove affected portions.