Issue: September 6, 1999

Overwintering geraniums

My geraniums are growing and doing beautifully this year. I like the geraniums and want to save them over the winter to plant next year. How can I do that? I have tried to dig them up and grow them indoors without much success, they always die in the winter.

The geraniums should survive the winter if you dig them in the fall before the first frost pot them in an appropriate potting soil and care for them properly in a well lighted room. It is important that the potting soil replace the native soil, especially if the texture of the soil differs greatly from the potting soil used. If the potting soil is too different from the garden soil that you dig it will create watering problems. It may be easier to use the garden soil as the potting soil, but even that can cause some problems. If the soil has much clay in it, as the soil dries it will crack and pull from the sides of the flower pot. Then with subsequent irrigations, the water will run through the cracks and out of the pot without moistening the soil. This could be a cause of the loss of the geraniums during the winter. If the soil moistens well, but holds too much water, that may also cause problems. Proper potting soil is critical.

When growing indoors geraniums need a well lit location. As with most flowering plants, insufficient light will result in weak growth and poor flower production during the winter. If a brightly lit location is not available, try to keep the plants cool but well above freezing to slow their growth and reduce the need for bright light.

Geraniums seem to have little trouble with insects which infest other house plants, but there are some insect problems for which you should be watching. You should check the plants carefully before bringing them indoors to prevent insect problems. Later, as the plants are growing indoors, check them frequently for insect pests. If insects are found, take samples to your local Cooperative Extension Service Office, Master Gardeners, or garden center to have them identified and to determine a proper treatment strategy. Remember to be especially careful if insecticides are needed. Choose a product labeled for indoor use.

If you water carefully, diseases should not be a problem. If disease symptoms appear, as with the insects, you should get the disease identified so that a proper management strategy may be selected.

It is possible to reduce the degree of difficulty if you are only trying to keep the plants alive through the winter for replanting outdoors next year and not interested in having them flower through the winter. It is possible to dig the plants, store them in paper bags without soil through the winter. To do this they must be kept in a very cool place. In most of New Mexico an insulated garage where they will not freeze may provide a good storage environment. The geranium is a succulent plant that can resist extended drying periods. It may help to moisten the stored plants by misting them occasionally in the winter. However, do not keep them too wet.