Gardeners commonly grow geraniums as annuals because these tender perennials often fail to survive the winter in most of the United States. With proper autumn and winter care, geraniums will survive the winter, especially when grown as container plants. Cutting back the plants offers several benefits, including a more uniform growth.
In the autumn, cutting back geraniums helps prepare the plants for overwintering in pots inside the house. Begin the preparation for overwintering geraniums long before there is a threat of winter frost. Begin when the temperatures begin to cool, often in late September or early October for most of the United States. Often, geraniums require a second pruning in late winter or early spring to encourage uniform, attractive growth. Overwintering indoors can cause geraniums to develop a leggy, unruly growth pattern.
To properly overwinter geraniums in pots, lift the plants from the garden, carefully digging them up to include all of the plant’s roots. Place the entire plant into a flower pot large enough to hold all of the root material. Generally, 6- to 8-inch pots work well for overwintering geraniums. Cut back the plant until it’s about one-third of its original height. Water until the soil feels moist to the touch. Store in a sunny, south-facing window. About one month after removing the geranium from the garden, treat monthly with a slow-release fertilizer.
After the threat of a winter freeze passes, transfer geraniums back to the garden bed or move pots outdoors. At this time, perform a second pruning. Cut back any leggy, unsightly growth. Be sure to remove any dead or brown plant material. If necessary, cut the plant back to one-third of its original height again. This helps encourage the plant to grow in its natural, bushy shape throughout the spring and summer.
Geranium gardeners often take cuttings of the geranium throughout the growing season to produce new plants. This procedure can be done at any time, but many choose to do so in the autumn when preparing plants for overwintering. Cut off a 3- to 4-inch-long shoot tip using a sharp knife. Remove lower leaves and dip the end in a root hormone for best results. Stick the cutting in coarse sand. Roots should develop in about three to four weeks.