Question
what is the best method to over winter geraniums?

Answer
the best way is to give them a sunny location inside (greenhouse window, N, S, or East exposure). treat them like a regular houseplant inside. water by weight. the pot should feel heavy after watering (about once every 5-14 days- depending on pot size, exposure, temps, etc.). do not keep them constantly wet as they will rot easily, especially during the winter short daylite hours. pick off old flowers & foliage as they develop. stop fertilizing in september. in spring after temps stay 45 or above at night put them back outside and start fertilizing again. you can remove some of the old soil in the pot and repot them w/new indoor mix before setting them out again. as long as the temp outside is 50 or above you can put them out for short periods (as long as temp is above 50). there are other ways (remove dirt from roots, hang upside down in a cool area-above 45-, and repot them in the spring). i prefer keeping them as an intact plant(rootball, pot, and foliage all together) inside.
it's good to try and overwinter them. if it doesn't work buy new in the spring and try again.