My mother was given an Aloha Lilly that was in some type of trouble. It is wilted and a check of the soil showed it was moist. She felt it may have been overwatered because the person who gave it to her advised she had watered it several times and when that did not seem to help she put a saucer of water under the pot. In looking at the Cannas information it seems that Cannas likes water?
Just on this sketchy info do you have any suggestions?