This year, I am digging up as many of the geraniums as I can fit onto two large tables in the barn and I will let them overwinter there. So far, I dug out about 50 plants, carefully getting as many roots as possible. Each plant is trimmed back so that only a few stems with leaves remain, and then placed in a flowerpot with potting soil. Our barn will be rather cold, but I hope they will make it. I have kept potted geraniums in my cellar before (which also gets rather cold), but it has very little light and I ended up with very spindly looking plants. I also tried shaking off all the soil from the plant and placing them in brown paper bags to overwinter in the cellar – letting the plant go completely dormant. Some of those actually do come back to life, if I remember to plant them early enough. I found that keeping potted geraniums in a cool spot with light seems to work best for me.