When you bring houseplants indoors before temperatures get too cold, be sure to leave pest problems out in the cold.

A rule of thumb is to bring plants in before night temperatures drop below 50 degrees Fahrenheit to allow plants to adjust to warmer indoor temperatures. It’s a good idea to inspect plants for pest problems several weeks before you plan to bring them inside. This precaution gives you ample time to take care of any insect or disease problems.

To combat foliar diseases, indicated by yellow, black or brown spots on leaves, remove and destroy the affected leaves; leave ample space between plants; avoid wetting foliage; and move plants to a less humid area.

Root and stem rot diseases usually occur under extremely wet soil conditions; so provide good drainage and avoid over-watering plants.

You usually can control small infestations of common insects, limited to a few plants, without using insecticides. For example, spray plants with water to wash off mites, or use a swab dipped in rubbing alcohol to remove light infestations of aphids, mealybugs and scale. To eliminate heavy infestations, use a soft brush or cloth dampened with soapy water solution of two tablespoons of mild soap per gallon of water.

If you decide to use a conventional insecticide on heavy infestations, always follow the
manufacturer’s label instructions. Insects can cause serious problems on plants inside during the winter, because the natural predators that help control these pests outside are
not in your home. So, separate the plants you’ve just brought in from others for several weeks to ensure the newcomers don’t have insects that might travel to the other plants. Regularly inspect all plants to control inconspicuous pests you might not notice until a serious problem develops.

Once you bring plants inside, provide a favorable growing environment including light, humidity and fertility. And remember, most plants don’t like to be in a draft. Optimum conditions reduce the chance of disease problems. Some symptoms are leaf edge and tip death, leaf drop, yellow leaves and spindly growth.

For more information on plant pest control and other gardening topics, contact your local Cooperative Extension Service.

Submitted by Rick Durham, Horticulture Specialist, University of Kentucky & John R. Hartman, Extension Emeritus Faculty, University of Kentucky, Department of Plant Pathology