Curtis,
My recommendation will apply only to cannas growing from rhizomes that are reasonably healthy and NOT canna seedlings. If your potted cannas get leggy it is advisable to cut the new growth back to about two inches of the soil line. Generally there is enough stored food reserves in the mother rhizome to produce new growth either from near the base of the removed canna top and often the cut top will continue to re-grow from the toped off stalk. Obviously, you cannot continue to repeat this operation often or the stored food supply will be insufficient to support the regeneration of new growth.
Remember that sunlight or the lack thereof is the most significant issue responsible for the leggy growth. Potted cannas growing at room temperature will or should produce feeder roots and a very, very, very light application of fertilizer will be of benefit. If you are using a sterile potting soil you will need to use an organic fertilizer because the soil does not contain the necessary soil organisms to break down and convert the commercial fertilizers. I would not over water these plants. DonÂt worry too much about the fertilizer for the short term.
Very small or weak one eyed rhizomes may or may not survive this procedure.
Kent

Wow, thanks canna2grow....these are incredibly detailed suggestions. Thank you
I did add a small bit of Espoma Bio-tone Starter to the potting soil because it says it contains mycorrhizae and I read that was good for Canna. I wonder if it would be a good idea to place it outside on "nice days" until our last frost date passes. Today for example was in the 70's but we're supposed to dip back into the 40's later this week. Would it be bad to keep moving it inside/outside as the weather permits or will that be too much shock for the plant.

I donÂt know anything about your soil additive. The idea to place your cannas outside under the MILD weather conditions would be excellent. As you suggested, be sure the temperature change is not severe enough to cause plant shock. Try for full sun and be sure the location is in an area that offers protection from strong winds.
These same suggestions can apply to hardening off the plants just before setting out in the late spring or early summer except the duration of exposure would be greatly increased if weather permits.
Kent