Answer: That could work as long as they do not become overly root bound. Perhaps you could set your larger containers on casters to help move them indoors for the winter? (You definitely can't leave them outside in containers of any size, the grafts become damaged by the cold winter weather even if the roots manage to somehow survive.)
Here are a few storage tips; in my experience the most common reason for losing them in storage is that they are kept too warm. They need to be kept cool ( say 40 degrees) and dark (to keep them from growing too soon), the soil should be kept barely damp just not bone dry for the storage period.
You would move them indoors in late fall once the weather has turned cold and growth has stopped, they can handle frosts and some freezing but not extreme cold. In spring you would take them back out again as soon as the bitter weather has passed so they can wake up naturally with the season. You would need to stop feeding them in early fall and stop deadheading as well to help them go dormant.
The other thing you could try is plant them in the ground and then do the Minnesota tip -- sever the roots on one side and tip them over flat to bury them in a trench. Refill the soil over top of them and also mulch heavily on top of that. Again you would do this in late fall, unearth in early spring.
I hope this helps.
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