How can I over-winter my geraniums indoors?
Geraniums (Pelargonium) can be overwintered indoors by potting up individual plants, taking cuttings, or storing bare-root plants in a cool, dry location. Remove plants from the garden (or take cuttings) prior to the first fall frost.
Overwintering as Potted Plants
Carefully dig up each plant before the first fall frost and place in a large container. Water each plant thoroughly, then place the geraniums in a bright, sunny window or under artificial lighting. Geraniums prefer cool indoor temperatures. Daytime temperatures of 65 to 70 degrees Fahrenheit and slightly cooler night temperatures are ideal. During their stay indoors, water plants when the soil surface becomes dry. Geraniums are likely to become tall and lanky by late winter. In March, prune back the plants. Cut the geraniums back by one-half to two-thirds. The geraniums will begin to grow again within a few days and should develop into nice specimens by May.
Overwintering as Bareroot Plants
Carefully dig up the geraniums before the first fall frost. Shake the soil from the plant’s roots. Then place one or two plants in a large paper sack and store in a cool (45 to 55 degree Fahrenheit), dry location. An unheated bedroom or indoor porch might be a suitable location. An alternate (somewhat messier) method is to hang the plants upside down in cool, dry location. The foliage and the shoot tips will eventually die. In March, prune or cut back each plant. Remove all shriveled, dead material. Prune back to firm, green, live stem tissue. After pruning, pot up the plants and water thoroughly. Place the potted geraniums in a sunny window or under artificial lighting. Geraniums that are pruned and potted in March should develop into attractive plants that can be planted outdoors in May.
Overwintering by Taking Cuttings
Using a sharp knife, take 3- to 4-inch stem cuttings from the terminal ends of the shoots. Pinch off the lower leaves, then dip the base of each cutting in a rooting hormone. Stick the cuttings into a rooting medium of vermiculite or a mixture of perlite and sphagnum peat moss. Pots and flats with drainage holes in the bottom are suitable rooting containers. Insert the cuttings into the medium just far enough to be self-supporting. After all the cuttings are inserted, water the rooting medium. Allow the medium to drain for a few minutes, then place a clear plastic bag or dome over the cuttings to prevent the foliage from wilting. Finally, place the cuttings in bright light, but not direct sunlight. The cuttings should root in 6 to 8 weeks. When the cuttings have good root systems, remove them from the rooting medium and plant each rooted cutting in its own pot. Place the potted plants in a sunny window or under artificial lighting until spring.