Before the danger of frost, dig up or carefully uproot your geranium plants from the garden. Ensure you dig up as much of the root ball as possible. Turn the plant upside down and shake off as much dirt as possible.
With clean pruning shears, prune all of the dead and diseased leaves and blooms, keeping the green full leaves. As you remove the leaves and blooms, check the stems and cut below any areas that show signs of disease or pests.
Prepare a cardboard box by adding several layers of newspaper at the bottom to provide insulation and cushioning for the plants. Carefully arrange the geraniums in the box upside down with the roots up. Space them out so they are not too crowded, but make sure they fit comfortably within the box.
As part of your monthly maintenance routine, consider soaking the potted geraniums in warm water for about one to two hours. This occasional soak can help rehydrate the roots and maintain their overall health during the winter months.