Remove any decaying organic material from the surface of the soil and ensure that the plant is located in a well-lit area with good air circulation to discourage mushroom growth. Avoid overwatering the plant and allow the soil to dry out slightly between waterings. Preventing Brown Mushroom Growth in Potted Plants To prevent brown mushrooms from growing in potted plants, it is important to maintain proper watering practices and ensure that the soil is well-draining. Self-watering ...