Geraniums are everywhere in the spring, so I’m not sure why it became such a tradition to overwinter geraniums for next season. I guess gardeners are a frugal lot and it’s hard to part with a perfectly good plant. Besides, it’s easy to store your geraniums for the winter. Overwintering geraniums doesn’t even need to take up valuable space under lights or in bright windows. It’s easy, but it’s not always worth it. The longer you keep your geraniums, the woodier the stems get and the less they will flower. They do acquire interesting bonsai type shapes, but if it’s a profusion of bloom you want, you’re better off getting new plants each year. Pruning will increase the blooming somewhat, but you’ll almost always get more flowers from a new plant.
I’m talking about zonal geraniums or Pelargonium here, not true geraniums. Zonal geraniums are only hardy to USDA Zone 8 (7 in a good winter). Gardeners in other areas basically have 4 choices of what to do with their geraniums after frost: Let them die off as annuals, bring them indoors as houseplants, take cuttings and make more plants or store them dormant until next spring.