I threw my coleus away every year until I read two years ago about overwintering. It's pretty easy too, which made me think I should try. Bascially, once temperatures start consistently dropping below 50degF later in the day or evening, I bring my coleus inside. It's frost-sensitive, so if that gets to them, it's too late and into the trash they go. Then inside, make sure they're getting bright, but indirect light, like a sunny windowsill or a well-lit room. Mine are off to the side of a large living room that has a ceiling window. Indoor temps should stay between 60-70degF and don't place them near air vents (that dries the soil) I like that I don't need to water much, just when I see it looks dry. Lower light actually slows it down so it's not as thirsty in the winter inside.
Coleus plants that overwinter - Overwintering coleus is an easy process and one that can ensure these unique plants will show their bright colors again next year. They should get started before the first freeze, which usually falls in late summer to early fall. Overwintering Tips The perfect environment for overwintering is a well-lit indoor area with temperatures of 60 - 75 degrees F and indirect lighting. More mature plants can be potted and brought indoors or rooted from cuttings in a glass of water or set directly in the soil. Care during the winter months involves very little watering to just keep the soil slightly damp along with occasional pruning of dead leaves and shaping. It does not need to be fertilized during this time of dormancy. Inspect for pests and provide adequate airflow to avoid mold or mildew. Sterilize your pots and cover them with fresh soil to prevent disease. Coleus can also save money on new plants and help you get a head start on garden planning for the next growing season.