Hello
Mine have not bloomed in 2 years. However last year I dug them up when they got hit by frost. That is when my canna and dahlia leaves got black and wilted.
Will be doing the same this year.

I agree with Gwyn. I think after the first freeze, the cannas will turn brown overnight. That will be your indication that it is time to dig them. The rhizomes should be fine.

Hi Gwyn and Turtlegirl03:

Thanks for the advice. I can now wait a bit longer without too much fear. Many thanks again!

Euphemia

My cannas got hit by frost at last and I dug them all up yesterday evening. The one that was bearing buds didn't get to bloom after all, but I at least get to see that it is another yellow. The rhizomes have grown quite huge since they were put in end of July and there are a lot of young "eyes". I broke some of these while digging. Can I assume that each broken piece will become an individual plant, no matter how small it is? Also I can see that the tissues of these young eyes are very fresh and tender. I just wonder if they will rot easily. I intend to wash away the soil with water, dry them and then store them. Will this do any harm to the canna rhizomes? Thanks for any advice in advance!

My canna were hit by frost as well and I am not going to be able to dig up till Sunday. Is dark when I get home.
Last year I washed off and then let dry in garage for a couple weeks, then wrapped in paper and put in a cardboard box in the basement. This year I will probably not wash off.
Not sure this answers the question.

I have never washed my canna rhizomes when brought in for the winter. The less you disturb the roots the faster they will start when put out in the spring.