My Mom tried this bare root method once, but not all survived, some did. She hung the geranium upside down in a brown paper bag, in a cool basement. Once in a while she'd go and spray the roots with water. Come spring time she'd pot it up and brought it to a sunny window. But the method I would use is leaving the plant in the pot, less chance of root drying off too much. Store it in a cool basement. no light necessary. If the dirt gets to dry give it a little water, just to dampen it a little, so the roots don't dry out completely. Come spring around March, bring it out to a sunny window, water, and feed.This is how I keep my fushias, and tender plants overwinter.

I'll try that. It never dawned on me that they could survive in the dark with hardly any water. Thanks alot.