Mold on the Soil of a House Plant

Causes

• Mold spores dwell within porous, moist materials. Since soil is naturally absorbent and contains moisture for long periods of time, it allows airborne mold particles to become active. Soil mold may also result from powdery mildew, a fungus that collects and grows most commonly on leaves and can spread to other parts of a plant. Other contributing factors include lack of sunlight and air circulation.

Improving Air Circulation

• The acceleration of air flow can kill mold spores by drawing moisture outward and providing plants with a source of warm air. You can achieved increased air circulation by placing the plant near an open window and by using a trowel or other small tool to break up the soil. This will allow air to penetrate deeper into the soil. If you have excess mold appearing on your soil, you may also want to consider re-potting the plant with new soil.

Limiting Relative Humidity

• Since mold requires moisture to remain active, it thrives best in environments with high levels of relative humidity. If you live in an excessively humid environment, take steps to keep the inside of your home as dry as possible. You can achieve this by running a dehumidifier or an air conditioner when high humidity occurs. If only certain areas of your home are affected by high humidity (such as poorly insulated areas), consider moving your house plant to a less humid location.

Powdery Mildew

• If your mold occurs as a result of powdery mildew, you can bring the problem under control by following the aforementioned suggestions in addition to pruning the dead and mildewed leaves. If you do have powdery mildew, you will notice a browning or a light, web-like coating on some of the leaves. Remove these leaves to stop the fungus from spreading even further, and apply a commercial fungicide safe for houseplants.