Have you ever seen a yellow mushroom growing from the soil of one of your pots? If not, then you probably haven’t noticed this little fungus before.
These yellow mushrooms aren’t uncommon; they won’t harm your plant and they aren’t harmful to you. They’re just a small part of the ecosystem doing its job in a pot of soil that happens to be in your home (or in my case, in a plant on the front porch).
The yellow houseplant mushroom (Leucocoprinus birnbaumii) is a yellow to white fungus often seen growing in potting soil used in houseplants. It starts out as a bright or pale yellow fuzzy patch on top of the soil and then develops into large parasol-shaped mushrooms. The fungus likely came in with the potting soil you purchased from the store. It isn’t harmful to you (unless you eat it), but it is nearly impossible to remove from the soil.
Where did the yellow mushroom come from? The yellow houseplant mushroom (Leucocoprinus birnbaumii) probably came in the potting soil you bought for your plant. The mushrooms produce spores which are tiny, often microscopic “seeds” that can then create new fungi.
This mushroom, also known as the flower pot parasol or yellow parasol, can remain dormant in the soil or surface for a long time before producing mushrooms or growing into mycelium. The spores of this mushroom may have been in the soil or surface for years before they started to grow. This yellow mushroom begins to grow when I overwater, or when it’s an indoor potted plant, it grows when the weather is really humid and rainy. I’m really bad about watering my houseplants – it’s either jungle or desert for these guys.
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Does it have any harmful effects?
Mushrooms aren’t scary at all. In fact, they’re pretty much harmless unless you try to eat them raw. Most mushrooms are just a normal part of the ecosystem, and eating them won’t harm you. Just don’t Google “human medical mycology.” I mean it, don’t. You can’t unsee some things. Tom Volk, a well-known mycologist at the University of Wisconsin, wrote in his article that you won’t get sick or poisoned by handling or touching mushrooms – only by eating them.
Volk recommends avoiding consuming this mushroom unless you know exactly what species it is. Some studies show it can cause gastrointestinal issues. So, while handling this yellow mushroom shouldn’t cause you any harm, it is possible that some people could have allergies to specific fungi and their skin might react negatively to touching a mushroom. If you’re concerned, wear plastic gloves.
If you have pets that tend to eat things that they shouldn’t, you probably want to remove the plants and its pot from your home. You never know what a pet might eat and they react differently than humans do. The yellow houseplant mushroom isn’t harming your living plants either as it feeds on dead organic matter in the soil – such as dead leaves, pieces of wood, or other stuff. As long as your plant is alive, it is safe from this fungus.
Is there anything you can use to remove it?
This mushroom grows very quickly, so you can expect to see results within just a few weeks. While you can physically pick and remove the mushrooms – that’s only the most visible part of this fungus. It is nearly impossible to remove all of the spores and mycelium from the potting soil that can produce more mushrooms in the future. Short of tossing out your entire houseplant, garden, and pot, you can’t really get rid of it. Try keeping to a regular watering schedule that doesn’t keep the soil too wet and you will reduce the chances of the fungus producing any mushrooms.
The most complicated and risky course of action would be to remove all the soil from the plant’s roots. This could cause the plant to enter shock. There is also no guarantee that you will get rid of all the spores, and after all this effort, the mushrooms may reappear.
Replacing several inches of top soil isn’t as drastic as removing and replacing it, but it won’t necessarily remove all the spores.
An easier way to eliminate the possibility of mushroom contamination is to remove the mushrooms once they appear, before they begin growing again. This eliminates the risk of them re-sporing – unless the spores are coming from another source.
Fungicides are often applied to plants to prevent fungal diseases. They are usually sprayed onto leaves or soil. Fungicides are generally safe to apply, although some individuals do develop mild allergies to them. However, because they are not 100% effective at controlling disease, it is recommended that you avoid applying them unless absolutely necessary. To learn more about how to grow healthy plants, check out our article here.
You could try changing the conditions that the plant is kept in – cooler temperatures, less humidity, drier soil, more air flow. This may reduce the abundance of mushrooms. However, this may negatively affect your plant because the conditions that most houseplants enjoy are the same conditions that mushrooms grow in.
Yellow mushrooms are very difficult to get rid of because the mycelium and the spores have likely settled deep within your plants’ roots and potting soil. It may be almost impossible to remove them entirely.
Is sterilization necessary before potting soil?
Sterilizing the potting mix before adding plant seeds ensures that you won’t end up with unwanted pests or weeds growing inside your pots.
The most effective way to sterilize small amounts of soil is by steam, or you can use a microwave or an oven. Soil needs to reach a temperature of 180 degrees Fahrenheit (82 degrees Celsius) before being exposed to sunlight.
Solarizing uses the free energy provided by the sun to heat up and thus sterilize the soil. Clear plastic or black plastic can be used. The sun provides free and renewable energy, so check out our article on how to solarize your garden.
Solarizing soil: step-by-step guide
- Remove debris and break up large clumps.
- Soak the soil thoroughly.
- Fill clear plastic bags with soil. If you live in a warmer climate, use black plastic bags as this helps retain more heat.
Alternatively, cover heaps of soil with plastic sheeting that is anchored down tightly. Make sure your plastic-covered soil is in a location that receives the maximum amount of sunlight.
Let the soil sit for four to six weeks. This process will rid the soil of any pests, weeds, unwanted seeds, and fungi spores while breaking down plant matter, and improving its nutrient content.
The Yellow Mushroom life cycle
The first thing you might notice is a bright yellow fuzzy patch on the top of your potting soil which in a few short hours starts to produce little knobby bumps that rise an inch or two off of the soil. These little bumps have turned into full-fledged yellow mushrooms the shape of a parasol. The mushrooms may begin as a bright yellow color and gradually change to a light orange or even white at the end of the day. As the mushrooms dry out over the next few hours, they will turn into a sticky mess on top of the soil. Mushroom blooms last anywhere from 1 to 2 days. Be quick to capture it all.
Unless they pose a threat to humans or animals in your home, we think you should make peace with the yellow mushrooms in your potted plants. They are not harming your plant, and, in fact, they are a sign that your plant is growing in good soil and the right conditions.