In this article, originally published on November 21, 2016 and ranked as the 11th most viewed article, Larry Hodgson discusses a common but little-known phenomenon: the presence of fungi in houseplant potting soil. He explains the reasons for their appearance, their role in the pot’s ecosystem and shares practical tips for keeping them under control. Although often harmless, these little organisms can be surprising, but with the right gestures, it’s easy to ensure a healthy environment for your plants.
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Sometimes mushrooms pop up in the pots of our houseplants. These are almost always harmless to the plant, living instead on decomposing potting soil. Besides, if you thought that the soil of your houseplants was sterile, think again: it is a living microcosm containing all sorts of fungi, bacteria and other microorganisms. And that’s actually a good thing, because most of those living things are beneficial to your plants: they help decompose the soil, releasing the minerals your plants need for their growth.
What To Do?
Of course, finding mushrooms in your houseplants can be a bit of a shock. If they disturb you, you just have to pull them out and aerate the surface of the potting mix with a fork to try to eliminate the mushroom’s hyphae (roots). If they grow back, try again. In some cases, it may be wise to repot the plant and change the potting mix, as mushrooms generally prefer older soils that are already fairly decomposed to fresh ones.
Fungi in potting soil often appear due to excess humidity combined with a lack of ventilation. To limit their presence, start by reducing the humidity of the potting soil. Allow the surface of the potting soil to dry between waterings, and avoid overwatering. Make sure the pot is well drained, with holes at the bottom to allow excess water to drain away. A simple trick is to water only when the first centimetre of potting soil is dry to the touch. In addition, good ventilation is essential to prevent the proliferation of fungi. Place your plant in a well-ventilated area and avoid dark or confined corners.
Remember that the mushrooms found in our houseplants are almost never edible, and some are toxic. Although most indoor mushrooms are harmless to the touch, some species can cause skin irritation or allergic reactions in sensitive individuals. As a precautionary measure, it is recommended that you wear gloves or wash your hands thoroughly after handling visible mushrooms.
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