Why do a peace lily's leaves turn yellow?

The leaves of a peace lily can turn yellow if the plant's root system is completely dry. Yellow leaves indicate that the plant is in need of water. Peace lilies should be watered sparingly when the soil is dry to the touch.

These household plants do not require regular watering and grow best when the soil is a little dry, but they do need water in their root systems to survive. Peace lilies are sensitive to chemicals that are found in treated water, and they thrive more easily when water is given toward the bottom of the plant. The leaves of this plant cannot tolerate chlorine and other chemicals.