Overwintering Geraniums: 3 Tips for Overwintering Geraniums

Overwintering a plant is the process of ensuring a plant survives the winter by protecting it from the cold and providing the extra light needed in the long, dim winter months. In the case of geraniums (Pelargonium), an annual flower in all but the warmest climates (in USDA zones ten and eleven, they are perennials), there are a few methods gardeners can use for overwintering.

There are different methods for overwintering geraniums. Depending on your climate, the resources you have at your disposal, and the condition of your geranium plant, you can choose which method works best for keeping your plants alive through the winter and into next year.

1. 1. Bring geraniums indoors. You can move geraniums indoors during cold months if you have southern-facing windows for ample light or grow lights. First, check for any pests, signs of disease, or general indications of stressed plants—you are most likely to have overwintering success with healthy plants. Next, dig up the plants you want to overwinter. Pot and prune the geraniums, taking extra care to remove dead leaves. Reduce the plants to about a third of their previous size. Water them generously, then let the soil dry. Bring them inside and near a sunny window when it starts to get cool out, making sure to do so before the first frost, which can kill the plants.
2. 2. Let your geraniums go dormant. You can keep the plants alive through the winter by allowing them to go dormant. Pot them, then prune them back to half the size and allow the soil to go dry. Place a paper bag over each potted geranium plant and put them somewhere cool and damp—a basement is usually ideal for keeping geraniums in dormancy. When storing dormant geraniums, check them every few weeks to ensure they aren’t too dry. If they are withering, spritz with a spray bottle of water, and replace the paper bag. A variation on dormant storage of geraniums involves digging them up but forgoing repotting. In this case, you simply shake the roots loose of any excess dirt and let them dry for a couple of days. Then, either hang the plants upside down, cover them with a paper bag, or store geraniums in a closed cardboard box. Store in a cool place, checking periodically to ensure they aren’t getting overly dry. If necessary, spritz with a water bottle, let them dry completely and place them back in their storage area.
3. 3. Propagate your geraniums. Another way to overwinter your geraniums is by taking cuttings to propagate new plants. Start the process during a lull in the plant's flowering. Just above a node on the plant—the spot on a stem where leaves emerge and grow—make a clean cut and remove the four to six-inch stem. Trim all the leaves and flowers, except for those at the very top. Then, moisten the bottom of the cutting and roll it in powdered rooting hormone or gel rooting hormone. Make a narrow hole in the damp potting soil with your finger, and place the cutting in the hole, being careful not to wipe away the rooting hormone. You can fit a few cuttings or several in the same soil, depending on the size of the pot, giving them a couple inches of spacing. Then firm the soil around the stem and place the pot near a bright window or under a grow light.

The best way to overwinter geraniums depends on the growing conditions in and around your home, as well as how much experience you have with repotting, propagating cuttings, and other methods of plant care. Below are some helpful tips to make the process go as smoothly as possible:

1. 1. Watch for pests. The ideal environment for geraniums is outdoors, so bringing them inside as houseplants can cause stress, making the plants more susceptible to attack by aphids, fungus gnats, and spider mites. Give the plants you want to overwinter a close inspection before bringing them inside, and keep a watchful eye out once they’ve been relocated indoors.
2. 2. Get a head start. When bringing geraniums inside for overwintering, be sure to start early when the weather begins to cool. By making the transition gradual, the plants will have time to adjust to the lower levels of light and humidity they’ll experience inside the house.
3. 3. Make an indoor greenhouse. Using the cutting method, you can put your plant in a small greenhouse or container. After treating the cuttings with rooting hormone, place the plants in rooting media and tent the container they’ve been placed in with clear or translucent plastic—a plastic bag works well, securing the bottom to the pot with a rubber band. You can use a few sticks to keep the bag from collapsing on the new shoots. The greenhouse will help concentrate warmth and humidity to boost the cuttings. After seeing new growth in six to eight weeks, transfer it to the pot with regular potting mix and place it in direct sunlight.

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