When it comes to plants in the home, we often tend to think of them on their own, often forgetting how each pot of soil is a tiny ecosystem. Microorganisms like fungi live in the potting soil, and the relationship between the fungi and plants is largely symbiotic. So occasionally—when the conditions are ideal—some fungi in the soil will produce mushrooms too.
The fungi present in the plant’s potting soil actually serve two major functions, and both are equally necessary for the plant’s health and vitality.
For one, the fungi help the plant by selectively absorbing forms of nitrogen and acidifying the soil. This acidity is important because it helps to solubilize and mobilize the metals and phosphates that are essential for the plant. These are either absorbed by the plant’s roots, or delivered via the fungi.
Excess nitrogen also leaks into the soil from the fungi. The plant usually trades carbon with the fungi for nitrates, phosphates, and other minerals—and since fungi are open organisms, they allow some of these to escape back into the soil. (Naturally, the plant completely capitalizes on this.)
In other words, fungi help by breaking down beneficial nutrients in the soil the plant can then use. They can also help to extend the plant’s nutrient range by forming vast underground networks that pull these minerals and nutrients into the plant’s roots.
In addition to providing nutrients, fungi also allow for chemical communication amongst plants. In fact, it’s been shown fungi allow for insect-attacked plants to communicate with their neighbors—and as a result of this, nearby plants will boost their own innate defenses if they hear over the fungal network that one of their neighbors is being attacked.
So, if you see a mushroom in your houseplant’s soil, don’t fret: It’s harmless to your plant (even though it might be toxic if you consume it yourself). Consider it a sign of a happy and healthy mini-ecosystem inside your home.
The Sill is a garden shop based in New York City that specializes in indoor plants perfect for city apartments. At The Sill (or on their website), you can shop, learn, or work hand-in-hand with a dedicated Plant Specialist on a plant design and maintenance program.