What is the best temperature for houseplants?

Most houseplants do well at 68° to 70°F during the day, with a drop—as in nature—to 55° to 60°F at night. Temperatures much higher or lower are generally harmful, but some plants (such as cyclamen, primrose, and strawberry geranium) require lower-than-average house temperatures—even down to 50°F in the daytime.