Most need to be back indoors before the night temperature drops to 50ºF, and though some hardy ones could stay out until it regularly approaches 40º, most of them will do better if they can start readjusting before the difference between indoors and outdoors becomes too great.
Before bringing in the plants, get the house ready by washing your windows (Ugh! I know, but clean windows let in a lot more light). If possible, while the plants are still outside, move them into shade ahead of time to prepare them for the drop in light in the house. As you bring the plants indoors, soak the pots up to their rims in a sink full of water to force insects to the surface, which you can then dispose of properly rather than finding them crawling on your floor later.
It’s best to leave repotting until just before the new growing season begins in early spring. Moving to larger pots means more growing medium, which holds more water. With lower light levels, and shorter days, overwatering is more dangerous than being a little potbound for the winter.
And quit fertilizing! They worked hard at growing all summer, so give them a rest until they start actively growing again in late winter/early spring.
Written and posted by Vicki