Some of mine have shoots as well. I store mine in a cool dark place (well cupboard). I'm thinking of potting them inside to get them growing. I nicked and sprouted some seeds and have them started as well. I was at the local garden center today and they have canna roots for sale. So of course, I couldn't resist buying a couple more. Canna has become my obsession in the past couple of year.

A canna sprouting in storage is a fairly common occurrence and generally is not a problem except the new tender growth may encourage young insects to multiply and feed on the tender growth. You can choose to remove the excessive growth just prior to planting and usually new growth will arise from either the center of the removed sprout or at the base of the same. I would cut back all sprouts that exceed three or four inches. If this Âtall new growth is planted and exposed to the typical outside conditions it will generally sun/wind burn and grow very slowly. Please do not remove the sprout all the way to the rhizome.
Kent