The widely used garden geranium is traditionally considered an annual; however, several techniques for overwintering are available that allow plants to be kept from year to year, replanting outdoors safely after the winter’s last frost.
Annuals are plants that complete their life cycle in one year, whereas perennials can live for several years. Because geraniums are not frost hardy and cannot survive at subfreezing temperatures, they are categorized as annuals. Unless you live in a tropical zone immune to cold winters, garden geraniums must be brought indoors if they are to survive from year to year.
An easy way to overwinter geraniums is to prune plants to half their size, repot and bring them indoors before the first frost. Keep by a window with southern exposure for maximum sunlight. Another option is to take 3- to 4-inch cuttings using a sharp knife and rooting hormone to spur new plants over winter. If you have a cool, dry basement, try the dormant storage method by removing soil from roots and then hanging the plant upside-down.
After successfully overwintering your geraniums, replant outdoors only after your last-frost date, typically in late May. New buds and shoots should appear within a few weeks, signs that this brightly flowered geranium will bloom another year.