Geraniums are lovely, colorful perennial plants that are often treated as annuals, but also require special care for winter storage. You can keep them outdoors during the cold season, but you will have to know the proper way to store them so that they survive winter.
If you are planning on bringing your geraniums indoors for the winter, dig them up thoroughly and place them in pots. Be sure to get the entire root. Prune your plant by about one-third. Geraniums will require generous watering and will need to be placed in a cool room in the house that also receives a good amount of sunlight. However, if the room you have in mind doesn't have enough sunlight, you should put a lamp in place for the plant's benefit and leave it on 24 hours a day.
Another option is to dig up the geranium bulb and hang it in your garage. This is a good option, as the plant can receive the coolness it requires but go dormant for the winter months. Remember to thoroughly soak the plant's roots in water for about an hour once a month. You can expect the geranium to lose all of its leaves, but this is normal when a plant goes dormant, or "goes to sleep." This will keep your geraniums healthy so that they'll thrive when spring returns.
If you would like to take cuttings from your outdoor geraniums for the winter, remove three- to four-inch sections of the stem with a knife. Cut into the rooting hormone. You can find rooting hormones in powder or liquid form at your local home center or nursery. Place your cuttings in a container where they will receive adequate drainage of water, with a type of sand soil. Make sure to keep them in a humid environment at all times for their survival.
Once the roots have grown about an inch long, you should plant the cuttings in their own small pots with well draining soil. Put them on a windowsill in the house so that they receive good amounts of sunlight, and regularly water them.