While plants need water to survive, to avoid root rot, the plant’s roots need to dry out between each watering. In fact, root rot caused by the roots sitting in too much water is the most common cause of problems and disease in houseplants. With a fast-draining soil, your plant’s roots will have access to the necessary moisture without the risk of root rot.  In our blog post on choosing the best soil for your houseplant, we discuss this in more detail.