Kenny,

You need to help us out with a bit more information and a photo would be helpful.

The full sun and watered daily is ideal. Are you growing them in the original pots or are they in the ground? Would you say the stems are weak or appear to be rotted at the soil line? How dense is the stem growth to each other? Are they growing in a high wind prone area? Have you use an excessive amount of nitrogen fertilizer?

Canna Australia is a tall growing plant and is not well suited for pot growth (if that is a factor). Any canna that grows 7 to 9 feet tall and produces large (heavy) flower heads may occasionally be blown over but that is more of an exception than a rule. Often this is a result of rapid growth due to excessive nitrogen which results in weak stems or overcrowded plants.

Kent

Kent thank you for the information. They are planted not potted in full sun (south side of house. I have a programed watering system (rainbird programable timer) I do not use fertilizers. I've had my soil tested and the N (nitrogen?) is 2.3 if that's any help. They started flopping before any real winds to speak of. The stems feel firm at the soil line. Short of digging them up, it appears like the root system just can't hold the weight. I looked up rust, I don't see any on them (I've read rust can weaken them and cause flopping). I'm not having success at getting pictures to upload from iPhone.Which doesn't help. I tap the image upload, nothing happens for some reason. I didn't think flopping was normal behavior for Australias, hopefully, the info I prvide will help you oor someone else move to a direction as to what it could be, for I am stumped.

Kenny, if possible you might consider sending your phone photo to your pc and simply downloading from there. A good photo would really be helpfully providing the file size is large enough to get a good look?

From your updated information I now suspect your cannas may be deficient in some important nutrients. Is there a reason you do not fertilize? Cannas are heavy feeders and require plentiful amounts of nutrients along with adequate water. They are not picky about the nutrient source; be it organic or otherwise. I am still concerned about the density of the plants. Cannas growing in dense beds produce very tall weak stems, causing them to simply fall over. Did you divide last yearâÂÂs clumps before replanting? A good 2 to 5 eye rhizome like Australia can be spaced at least 18/24 inches apart and by years end will have multiplied 4 to 5 times that original number.

Sorry but I am not sure what your soil test for nitrogen reading indicates but nitrogen must be added yearly in almost all horticulture applications. It simply does not replenish itself from one year to another. Your soil Ph reading is also important because it can lock up nutrients. A Ph reading between 5.5 and 7.0 would be good for cannas.
I do not believe rust is a problem for you at this time in your area. I wish I could be more helpful.

Kent

Kent thank you for the information. They are planted not potted in full sun (south side of house. I have a programed watering system (rainbird programable timer) I do not use fertilizers. I've had my soil tested and the N (nitrogen?) is 2.3 if that's any help. They started flopping before any real winds to speak of. The stems feel firm at the soil line. Short of digging them up, it appears like the root system just can't hold the weight. I looked up rust, I don't see any on them (I've read rust can weaken them and cause flopping). I'm not having success at getting pictures to upload from iPhone.Which doesn't help. I tap the image upload, nothing happens for some reason. I didn't think flopping was normal behavior for Australias, hopefully, the info I prvide will help you oor someone else move to a direction as to what it could be, for I am stumped.

Sorry for repost, I hit the wrong button, going to try your suggestion, to send picture via email to PC. I did not dig them up. Frost hit them, cut them off and mulched over them. I will be around a PC I can use later today.

Mine are doing the same Thing. I have tied them up , but I have never had one get 9 feet tall before.

The only ones I ever have that do this are my Omega's. I found that it came from the rhizomes being planted to shallow in the soil. once they started to spread and push themselves up they were almost at soil level causeing them to fall over..a quick dig and replant fixed the problem.