Assuming your rhizomes survived the winter storage, you can repot your cannas roughly 3/5 weeks prior to moving outside for the summer. If you have a heated and well lighted area you could start earlier. Once plants emerge, do not allow to freeze. Trimming the old feeder roots is not a problem. Most containers sold at Lowes and other outlets are not large enough for maximum potential growth. I would suggest a much larger container for each large 3/5 eye rhizome.
Best,
Kent

Thank you very much for the response. I believe the rizomes are fine. A couple look dead. Also I'm going to try planting a few in the ground but I know I'll have to dig them up in fall. Our winters are to harsh.