Zonal geraniums (Pelargonium x hortorum) are celebrated for their vibrant, long-lasting flowers and distinct, dark-ringed foliage. They are a staple of summer container gardens and flower beds, providing continuous color from spring until the first hard frost. Their popularity often leads gardeners to wonder if these plants must be purchased and replanted every year. Understanding the plant’s true nature and climate limitations determines if they can be saved and enjoyed for multiple seasons.
Understanding Zonal Geraniums and Their Perennial Status
Zonal geraniums are classified as tender evergreen perennials, meaning they possess the genetic ability to live for more than two years. This characteristic is fully expressed in their native environment, which includes the warm, frost-free climates of South Africa. They are subshrubs that will continue to grow and bloom year after year under the right conditions.
In gardening terms, this perennial status only holds true for environments that align with USDA Hardiness Zones 9 through 12. These regions rarely, if ever, experience freezing temperatures, allowing the plants to survive the winter outdoors without special protection. The plant’s succulent, water-storing stems make it particularly vulnerable to frost, which causes the cell walls to burst.
For the vast majority of gardeners in temperate climates, from Zone 8 and colder, Zonal Geraniums cannot tolerate the winter environment. Because they perish when exposed to freezing temperatures, they are practically grown as annuals in these locations. Gardeners who wish to preserve a favorite variety must intervene by bringing the plant indoors to shelter it from the cold, a process known as overwintering.
Comprehensive Guide to Overwintering Zonal Geraniums
Preparing geraniums for winter storage begins before the first hard frost, while the plant is still healthy and actively growing. Plants in the ground must be carefully dug up, while container plants should be moved to a sheltered area. Inspecting the foliage and stems for pests, such as whiteflies or aphids, is necessary to avoid introducing unwanted insects indoors.
Dormant Storage (The Cool, Dark Method)
The dormant method is an efficient option for gardeners with limited space, requiring the plants to be stored bare-root in suspended animation. After lifting the plant, gently remove excess dirt from the roots and prune the foliage back by about one-half to one-third. The plant can then be placed into an open paper bag or hung upside down in a cool, dark location, such as an unheated basement or root cellar.
The ideal temperature range for this method is between 40 and 55 degrees Fahrenheit, which prevents the roots from freezing but remains too cold for active growth. During the winter, the plants will naturally drop most of their leaves, but the stems should remain firm and green. It is important to check the plants monthly, and if the stems appear shriveled or dry, soaking the roots in water for about an hour before returning them to storage can prevent dehydration.
Growing Indoors (The Windowsill Method)
Bringing Zonal Geraniums inside to grow as houseplants is a straightforward method, especially if they are already potted. Before moving them, prune the stems back by about one-third to reduce the plant’s size and manage the transition to lower indoor light levels. The container should be placed near a sunny south-facing or west-facing window to receive maximum natural light.
Indoor temperatures between 60 and 65 degrees Fahrenheit are generally preferred, and the plant should be kept away from forced-air heating vents. Water must be significantly reduced during the winter months, allowing the top inch or two of soil to dry out completely between waterings. The plants may become somewhat pale and develop long, sparse stems, a condition called legginess, which can be mitigated by occasionally pinching back the growing tips.
Taking Cuttings (The Propagation Method)
Propagating geraniums from cuttings is the most space-saving method and often results in more vigorous plants the following season. Select healthy, non-flowering stem tips three to four inches long and make a clean cut just below a leaf node. Remove all but the top two or three leaves to reduce moisture loss and prepare the stem for rooting.
While optional, dipping the cut end into a powdered rooting hormone can significantly speed up the formation of new roots. Plant the cuttings into a small pot filled with a sterile, well-draining medium like a mix of perlite and seed-starting mix. Place the pots in a spot with bright, indirect light and keep the medium consistently moist; roots typically develop within six to eight weeks.
Transitioning Geraniums Back Outdoors
The transition process begins in late winter or early spring, approximately six to eight weeks before the last expected frost date. Dormant, bare-root plants should be brought out of storage, and any dead or brittle material pruned back to firm, green tissue. The revived plants should be potted into fresh, sterile potting mix and watered thoroughly to encourage them to break dormancy.
All overwintered geraniums, including potted plants and rooted cuttings, benefit from a hard pruning at this stage to remove winter-damaged or leggy growth. Cutting the stems back to four to six inches promotes a compact, bushy habit and encourages more flower production later in the season. Place these newly potted or pruned plants in a sunny indoor spot to jumpstart active growth.
Before the geraniums move to their final outdoor location, they must undergo hardening off to acclimate them to the harsher outdoor elements. Start by placing the plants in a sheltered, fully shaded spot outside for a few hours each day. Over seven to ten days, gradually increase their exposure to direct sunlight and wind, ensuring they are brought inside if nighttime temperatures dip below 50 degrees Fahrenheit.