Although perennial, geraniums don’t survive hard frosts. They are often treated as annuals for this reason. The plants often wilt and die if grown them as indoor plants in winter because they don’t receive enough sunlight during the short days. Forcing the plants into dormancy allows you to keep your geraniums perennial, so you can enjoy them again the following summer.
Whether grown in a pot or the garden bed, geraniums require uprooting before storage. The plant goes dormant once out of the soil, allowing you to store it indoors with minimal care during the winter months. Dig up the geranium carefully, severing as few roots as possible, before the first fall frost. Plants exposed to frost die. Shake the soil gently from the roots after uprooting but don’t rinse any remaining soil off the roots. The soil dries and eventually falls off on its own.
The foliage won’t survive dormant storage but avoid damaging the thick, succulent stems. These stems store the water and nutrients necessary for the geraniums to recover from dormancy in spring. Cutting back the foliage by half its height makes the plant more manageable but doesn’t harm the stems. Set the prepared plant inside a large paper bag. Leave the bag open allowing air circulation, which helps prevent rot and fungus problems during dormancy.
Overly dry conditions kill the geranium. Keep the bag in a humid and cool 45 to 50 degree location. A basement or unheated garage usually provides a suitable storage area. Check the geraniums monthly during storage. If the stems shrivel and no longer appear firm and succulent, rehydrate the plants before returning them to storage. Soaking the roots in lukewarm water for one to two hours helps replenish moisture in the stems. Shake the excess water from the roots before returning the geraniums to storage.
The geraniums are ready to awaken from dormancy in late March. Inspect the plants and dispose of any with withered stems, as these plants have died and won’t resume growth. Repot the remaining geraniums into fresh potting soil. The stem tips won’t survive storage, so trim these back to the topmost bud or leaf node. Resume watering and place the geraniums in a sunny windowsill in a warm room. Growth typically resumes in one to two weeks. Move the pots outdoors or transplant the geraniums to the garden after all spring frost danger is past.