Q.transplanting canna lily
Once a canna lily has begun its growth and emerged from the soil, can it be transplanted? A canna rhizome was inadvertently put in a pot with a houseplant, which spent the summer outdoors. It is in north-facing window and somehow has begun to grow. I would like to keep it but am afraid it will kill the houseplant if left in the same pot.
I would go ahead and split the two apart and pot up the Canna in it's own pot. Then just let it grow until you are able to plant outdoors after the danger of frost has passed. I know many gardeners who start their Cannas indoors since they live in a zone with a short growing season.
Here is an article that may help you.