The common garden plants known as geraniums are technically Pelargonium species, which originate from South Africa and are classified as tender perennials. These vibrant, sun-loving flowers cannot withstand freezing temperatures and will perish outdoors after the first hard frost. To preserve favorite varieties year after year, special winter preparations are necessary to protect the plants from cold damage. There are reliable methods to ensure these perennial beauties survive the winter season and return to bloom in the spring garden.
Essential Preparation Before Winter
The first step in saving your plants is to act promptly before the first hard frost is even predicted for your area. Exposure to freezing temperatures can compromise the plant’s health and ability to survive winter storage. This preparation is universal, regardless of whether you choose to store the plants in a dormant state or keep them actively growing indoors.
Pruning is a necessary step that reduces the plant’s moisture loss and makes it easier to handle during the transition indoors. Reduce the overall size of the plant by cutting back the stems by about one-third to one-half of their height.
A thorough inspection for pests is also mandatory before bringing any plant material inside your home or storage area. Remove all dead leaves, spent flowers, and any debris that could harbor insects or fungal spores. Treating the plants with an insecticidal soap can prevent unwanted hitchhikers like whiteflies or spider mites from spreading to other indoor plants.
Overwintering Geraniums Using Dormant Storage
Dormant storage is the traditional and space-saving method, especially suitable for gardeners with a large number of plants. This process begins by lifting the plants from the garden or pot before the ground freezes. Gently shake off the majority of the soil and growing medium from the root systems to create a bare-root specimen.
The plant is then prepared for its long sleep by trimming the roots minimally, focusing on any long, straggly sections. The goal is to move the plant into a state of suspended animation where its metabolic rate is significantly slowed. This allows it to survive on stored energy reserves within its stems and roots.
The ideal storage location must be dark, dry, and consistently cool, with temperatures hovering between 45°F and 55°F. Unheated cellars, cool basements, or insulated garages that remain above freezing are suitable environments. The bare-root plants can be hung upside down from the rafters or placed loosely in open paper bags or cardboard boxes to ensure adequate air circulation.
Throughout the winter, the plants must be checked periodically, typically once per month, to monitor their condition. The stems should remain firm and the roots should not be allowed to completely dry out and shrivel. If the roots appear brittle or excessively dry, a minimal application of moisture is required, such as a light misting or a brief soaking of the roots in water for an hour before returning the plant to storage.
Maintaining Geraniums as Indoor Houseplants
An alternative to bare-root storage is to maintain your plants in active growth by treating them as temporary houseplants. This method requires providing the specific environmental conditions needed for successful winter survival. Geraniums need substantial light exposure to remain healthy and prevent the development of weak, spindly growth.
A south-facing window offers the best natural light, but supplemental grow lights, placed a few inches above the foliage, are often necessary to sustain them through the short, dark days of winter. The plants thrive in cooler indoor temperatures, ideally around 60°F to 65°F during the day, which helps them avoid becoming overly leggy. Warm air from heating vents or fireplaces should be avoided, as it can stress the plants.
The watering schedule must be drastically reduced from their summer needs to align with the plant’s slower winter metabolism. Water only when the top inch or two of the soil feels completely dry to the touch, which may be as infrequent as every two to four weeks. Fertilizer application should be completely suspended during the winter months, as feeding will only encourage soft, weak growth that is susceptible to pests and disease.
Reintroducing Geraniums to the Spring Garden
Waking up dormant plants or preparing indoor ones for the outdoors requires a gradual transition timed roughly six to eight weeks before the last expected frost date.
Waking Dormant Plants
Dormant, bare-root plants should be removed from storage in late winter or early spring. Prune them back to firm, green stem tissue, removing all shriveled material. Repot them into fresh potting mix, water thoroughly, and place them in a bright location to encourage new growth.
Preparing Potted Plants
Potted plants, whether freshly repotted or those maintained indoors, will likely appear pale and somewhat stretched out from their winter confinement. A spring trim, cutting back the stems by a few inches, will encourage bushier growth and a more compact shape for the growing season. Begin a light feeding schedule with a balanced liquid fertilizer once new growth becomes clearly visible.
Hardening Off
The process of “hardening off” is necessary for all overwintered plants before they can be permanently moved outside. This involves slowly acclimatizing them to the harsher outdoor elements, including direct sun, wind, and fluctuating temperatures. Start by placing the plants outdoors in a shaded, sheltered location for just a few hours each day, gradually increasing their exposure to sunlight and wind over a period of one to two weeks. The final move back into the garden should only occur once all danger of frost has definitively passed, and nighttime temperatures consistently remain above 50°F.