This week's cooler temperatures have me looking ahead to saving the geraniums around my house. There are three different ways to overwinter these popular flowering plants. Geraniums can be overwintered indoors by potting up individual plants, taking cuttings, or storing bare-root plants. Regardless of the method, the plants should be removed from the garden prior to the first frost.
If interested in potted plants, carefully dig up each plant and place in a large pot. Water each plant thoroughly and place the geraniums in a bright, sunny window or under artificial lighting. Geraniums prefer cool indoor temperatures with daytime temps of 65 to 70 degrees F and slightly cooler night temperatures. During their stay indoors, water the plants thoroughly when the soil becomes dry. The geraniums are likely to become tall and lanky by late winter. If that is the case, in March prune back the plants by one-third to one-half. The geraniums will begin to grow again within a few days and should develop into nice specimens by outdoor planting time in May.
If you choose to do geranium cuttings, use a sharp knife and take 3- to 4-inch stem cuttings from the terminal ends of the shoots. Pinch off the lower leaves and 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. Suitable rooting containers would be clay or plastic pots with drainage holes in the bottom. 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, and then place a clear plastic bag over the cuttings and container to prevent the cuttings from wilting. Finally, place the cuttings in bright light, but not direct sunlight. The cuttings should root in six to eight 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 newly-potted plants in a sunny window or under artificial lighting until spring.
Lastly, if you are interested in handling bare root plants, dig the geraniums and carefully shake all the soil from their roots. Place one or two plants in a large paper sack and store in a cool, dry location. An unheated bedroom or indoor porch in the 45 to 55 degrees F range would be a suitable location. A messier alternative would be to hang the plants upside down in a cool, dry location. The foliage and the shoot tips will eventually die. In March, cut each plant back to the firm, green, live stem tissue removing all the shriveled and dead material. After pruning, pot up the plants and water thoroughly. Place the potted geraniums in a sunny window or under artificial lighting and be ready to plant outdoors in May after the danger of frost is past.
After being indoors all winter, your geraniums will be ready for next spring's planting. While enjoying their color, you can invest your savings in new geranium varieties to overwinter next year.
We have a lot of information here at the Cherokee County Extension office about indoor plants and how to put your garden to bed for the winter. Stop by and check it out.
Cherokee County Extension, 209 Centennial, Suite A Cherokee, 712-225-6196.