If you use rotted/composted manure in the rest of your gardens, then by all means use it on your cannas.

I've had years where I've just tossed a handfull of general dry fertilizer around the bases and watered it in well. Other years I've used MiracleGro. I often mulch heavily in the Fall with chopped leaves and that feeds the soil as it breaks down, which in turn feeds my plants. I've even had several years where I didn't fertilize at all and still had cannas that were as gorgeous as the ones that I did fertilize.

Jenna