leave some in pots, plant some in ground. they will perform well either way.
probably a little easier when have to dig up rhizomes for winter if in a pot.
cannas love full sun and lots of water and fertilizer. will probably not bloom if in shade.
fern

I've taken the same variety in a pot and the ground and it definitely grew taller and fuller in the ground. Pots are easier to dig the tuber from in the fall.

You don't want to put them outside if there's still a chance of frost, which I suspect there is where you live. So either tide them over in their tiny pots (OK as long as you keep them watered), or uppot them.