If you notice a thin layer of white or gray on top of the dirt in your plant container, your indoor plant has white mold. The mold can look dried out and crusty, covering a wide section of the soil, or it can look like small dots or freckles resting on the soil.
Scoop off the moldy soil with a fork to get rid of it. Mold on the soil will not harm your houseplant. Follow up by providing better care. If you want, change out the container and the potting soil.
Wash containers with soap and water before repotting indoor plants to ensure the container itself is disease free. Use only sterile potting soil, which will be labeled as such. If you do not have or cannot find sterile potting soil, you can sterilize it yourself in the oven or microwave. Place soil in a baking pan in a 4-inch layer. Turn the oven on to 190 degrees F and slide the pan with soil inside. Heat the soil to 180 degrees F for 30 minutes to sterilize, testing the soil temperature with a dial or instant read thermometer. Do not allow the soil to go above 200 degrees F.
Provide indoor plants with better care so they do not develop white mold. Decrease the frequency of your watering, adding more only when the soil dries out to the touch. Do not add too much water so the plant sits in water. Increase the amount of air circulation by opening a window or adding a fan; this will help move bad air away from the plant. Give the plant additional light in the form of a plant light or placement in a window.
Don't allow dead or fallen leaves to sit on the soil in your container, since this could expose your indoor plant to new bacteria or fungi. Clean up fallen plant material before it rots, or trim this material off the plant when you see leaves wilt and wither.