Sometimes you have a perfect summer with conditions that have contributed to the most beautiful container of geraniums you’ve ever had. What to do in the fall — let them die off and try again next year, or attempt to keep them over the winter? If you’re tempted to keep them, you have some options.
The perfect solution would be a cool, damp basement (can you say cellar?), where you could just hang them upside down. Shake the excess dirt from the roots, but leave all that clings. Loosely tie a string around the neck area, where the stem meets he roots, and use this to hang them from a rafter or beam. They should get good air circulation; be sure they don’t touch each other or anything else.
A dry basement — as long as it is cool (35º to 45ºF) — is a distant second choice. In that case, you will need to pot them up and they will need a place that’s light. They should be watered thoroughly about once a month, but let them go dry in between — they’re hardly growing.
No matter which way you store them, remove buds and flowers, where the disease botrytis hides, and any leaves that turn yellow. Cut the plants back to 6 inches after planting them outside next year.
Even thought your geraniums appear healthy, they could have picked up at least one of the many diseases that affect geraniums during the summer. When they are ready to go back outside, the geraniums will be stressed from their winter treatment, but any disease organisms will be just fine so the plants may not be as healthy as you expect. Keep a little extra in the gardening budget for replacements.