Issue: October 26, 2002

Overwintering geraniums

I hope you have ideas on overwintering geraniums. I have 11 large pots overflowing with them. It has taken me several years to propagate them (you are welcome to have some). As in Mexico where I lived as a child, I have them massed to decorate my porch, both red and pinks. - Brenda L., Valencia Co.

I overwinter my few geraniums indoors in a sunny window. They tend to bloom through the winter. This works well for a few plants or if you have a large area that receives sufficient light.

If you choose to winter-over your plants indoors, you can also try pruning them back before bringing them indoors. Root the cuttings for insurance. To most successfully encourage root formation, let the cuttings lie out in a cool, shady location for a day or two. This allows the wound to close (become covered with suberin, a waxy substance). Allowing wounds to suberize is good practice for all succulent plants. When you place the cuttings in potting soil, choose a brightly lighted location (not direct sunlight). Bottom heat, or a warm location, helps them to form roots. After propagating, you may have extra small plants that don't take up too much space indoors, and you also have reduced the size of your larger plants so they are more manageable indoors.

A trick I learned in Montana was that some gardeners unpot geraniums and store them by hanging the geraniums in their cellar (soil floor, not a basement). We don't usually have cellars, so it is more difficult here. Also, the cellar had high humidity and low, non-freezing temperatures. I shared this technique with a county agent in Eastern New Mexico, and he tried it with a modification. He put his bareroot geraniums in brown paper bags and hung them in his insulated garage. It stayed cool and the bags helped reduce water loss. In the spring he replanted them and found he had lost about 3 out of 12. So, most did survive the conditions in the bags in his garage. Occasionally opening the bag and adding a slightly damp paper towel or very lightly misting the geranium stems may help maintain humidity and help the plants survive.

The massed geraniums you described sound very attractive. I hope you will be able to carry your geraniums through the winter. That will give you a faster start in the spring. However, if all else fails, buy some new plants early in the spring, get them started indoors in smaller pots, then move them to the large pots outside when the danger of frost is past.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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