Potted plants add beauty and life to a home's interior or exterior. Occasionally, a strange mushroom or fungus may pop up overnight. These can occur with a new plant, or with plants that have been stationary for years. Many people panic at the sight of them, and want to know how to eradicate the mushrooms from the potted plant.
Mushrooms and fungi in potted plants come in all shapes and sizes. The most common houseplant-invading mushroom is the yellow mushroom. The caps vary from high-domed and compact to flat and broad. "Dog vomit mold" takes its name from its appearance. There are oblong-shaped, yellowish-brown fungi. These "explode" with spores when they are touched.
Mushrooms and fungi grow in moist, cool, dim conditions. This is why most seem to pop up overnight. If you water too frequently, or if you use a water-retaining potting soil, this contributes to the optimum conditions for mushroom growth. If the plant in question is a new plant, the soil was probably infected with the spores when you bought it, and the dormant spores became active after you brought it home.
Only very severe cases need to be treated. To treat, find a washtub that is taller and wider in diameter than your plant's pot. Fill the washtub with water, and mix in a liquid fungicide. Carefully place the entire pot into the wash tub. Allow it to sit in the antifungal bath for several hours. Remove the plant, and place it in a hot, sunny area of your yard to dry out for a day or two.
Mushrooms and fungi in potted plants can be prevented to an extent. Use size-appropriate pots for your plants; a container that is too large requires more water than the plant needs. The excess water sits in the soil, creating a breeding ground for spores.
Water plants in the early morning, so that they have ample time for excess water to drain and evaporate.
Place plants in areas that receive plenty of sunlight throughout the day.
Resist the urge to pull mushrooms up and/or repot. Disturbing the mushroom will release millions of spores into the air. This will compound your problem, as those spores will most likely take root in your other potted plants, or in your gardening beds or lawn. Most cases of mushrooms in potted plants are self-limiting, and will go away after a while.