I have some cannas potted in pea gravel and sitting on a ledge in my pond. I notice this week that some leaves are turning brown....so do they need more water by putting them in deeper in the pond or do they need less water than they are getting and I need to raise them up...what do you think? Right now their pots are sitting in 3 to 4 inch deep water. They had been doing well for about a month before this week. Thanks for your time to help me.