Geraniums do not tolerate freezing winter weather, but gardeners willing to expend a little effort can bring the plants back year after year. Gardeners have a number of options that, depending on their circumstances, can give them a vibrant plant early the next year. Because the plant has no stored energy in the form of a bulb, it needs to winter either completely dormant or as a growing plant.
Transplant the geranium plant into an 8-inch pot prior to the first killing frost of the fall. Trim the plant to about one-third of its normal height before placing in the pot filled with potting soil. Water the geranium every few days while keeping it in a well-lit window or under an artificial grow light. The geranium prefers a nighttime temperature of about 60 degrees Fahrenheit, so keep it in the cooler part of the house.
Dig the geranium before the first killing frost of the fall. Shake the roots free of dirt and store in a potato sack or other ventilated bag. Store the bare plant at about 50 degrees Fahrenheit in an area with low humidity. A cool, dry basement is ideal. Soak the roots in water for an hour about once a month to keep the geranium alive through the dormancy.
Take cuttings from the geranium plant before the first frost of the fall. Start the cuttings in sand to develop roots. After the cuttings start roots, transplant into pots and grow through the winter as a houseplant. Follow the same procedures listed for the geranium houseplant.
Plant the geranium in the garden after the last threat of frost has passed in the spring. Transplant the plant, either started by cuttings or transplanted from the garden, into the soil and water. Trim the top of the geranium back to less than half its height. Plant the bare root dormant plant in the ground at the same time. Trim back about half of the previous year’s dried stems.