"Night temperatures are dropping and most houseplants are from tropical areas and will be injured or killed by cold temperatures and frost," she noted. "Houseplants need time to adjust to the lower light level in your home. Since this move will be a shock to them, it is best to introduce them to this change, gradually."
To start, Grupp recommends placing them on a covered porch or indoors for just a few hours and return them outside for the remainder of the day. Each day, increase the time in lower light. After 10-14 days, they should be better equipped to handle the permanent move indoors.
"While you are acclimating them to new growing conditions, you should check them carefully," she said. "Look for insect and disease problems. Stunted or distorted growth may be a symptom of a problem. If you find sticky leaves, look for sap-feeding insects such as aphids or scale. These insects excrete honeydew that forms a sticky deposit on leaves."
The plant's soil should be checked too for pill bugs, millipedes and ants, as all may be present. Although they cause no harm to houseplants, these pests can become a nuisance in the home.
"Washing leaves with plain water and repotting plants with fresh potting mix are good steps to take when returning houseplants to their indoor home for the upcoming cold season," Grupp said.