With nighttime and daytime temperatures dropping and hard frosts in the near future, it is time to turn our attention to bringing in and acclimating houseplants that have been outdoors during the summer. Most experts recommend transitioning plants from their present light conditions to lower light conditions over a period of several days when temperatures drop below 50-60 degrees which is typically in latter September in the midwest. When time does not permit this transitioning time, plants will likely show signs stress with yellowing and leaf dropping as they adapt to indoor light conditions.
Plants should be inspected and treated for pests before bringing inside. Aphids, mealybugs, white flies and other pests usually aren’t a problem when potted indoor plants are outside, but can quickly turn into a major infestation during the winter if they highjack their way inside. Some experts recommend bathing or soaking plants before bringing them inside in a tub of water with a mild dishwashing soap. If plants are too big for a tub, spray them with water and wash the top and undersides of the leaves as much as possible with water and dishwashing detergent rinsing with water; in addition to removing potential insects, it also removes outdoor dust from the leaves. It is important that the soapy water also get into the soil as it will help to kill any pests residing there, too. Wash the outside of the pots to remove dirt and any unwanted pests. It may also be a good practice to report the plants with fresh potting soil providing them with new nutrients and minimize the risk of insects residing in the soil. Once inside, plants should be checked with each watering for any sign of infestation and if spotted, treat religiously with an insecticidal soap until the problem is resolved.
Houseplants may put on a lot of new growth over the summer and may get very large. After cleaning, the second step is to determine if they need pruning, separating, or repotting. Some plants may have outgrown their pot and need something larger. Others may be too large for the indoor space and need to be pruned, separated, or propagated to start a new plant.
While geraniums are typically an annual plant, they can be successfully wintered indoors in different ways–left in their pot, pruned and repotted, propogated from cuttings, or stored as dry-root plants in a cool, dry location. University of Minnesota provides information on these methods.
Plants should be placed in the brightest locations possible in the home with a southern exposure if possible. Once the plants are inside a new kind of care begins–watching for pests, watering appropriately, cleaning up dropped leaves and petals, and fertilizing as needed. To prevent overwatering, that means letting the soil dry to the touch before watering. When houseplants need to be watered depends on many environmental conditions including light, humidity, and temperature. Depending upon the conditions of the home, some plants may need nearly as much water in the winter as they do in the summer. Iowa State University Extension horticulturalists recommend reducing or stopping fertilizing plants in the fall and winter months, as abundant fertilizer will only promote growth that cannot be supported by the slower-growing houseplant leading to pale or spindly growth.
Bringing houseplants, tropicals, and geraniums indoors for fall and winter is a great way to preserve special plants and save money by not repeatedly buying new plants each spring. It does take considerable time in the fall, but in doing so, one may be able to enjoy the same plants and collections for many years and use the money saved to purchase new or interesting plants.
Updated 10-12-2023 mg.