Mushrooms that pop up in plant pots are not going to harm your plant but they’re classified as ‘medium poisonous’.
They’re unlikely to cause lasting damage but whoever eats them (they’re not poisonous to touch) could get a severe stomachache.
I leave mushrooms where they are, because they disappear a day or two after they turn up so there's not really much point in me removing them, but if you have pets or small children that might fancy a bite of mushroom, then it makes sense to remove them.
Mushrooms are just the fruit of the fungus in the soil, most likely to be Leucocoprinus birnbaumii in houseplant soil.
Houseplant mushrooms tend to be the species Leucocoprinus birnbaumii.
They’re extremely common in nurseries all over the world, despite originating in the tropics. They’re even growing wild in a couple of forests in England now. Suffice to say, they’re not easy to get rid of.
How to remove houseplant mushrooms
Leucocoprinus birnbaumii won’t do you any harm if they only come into contact with your skin, so the easiest way to remove the mushrooms from houseplants is to just pluck them out with your fingers.
Just be sure to wash your hands afterwards, because if you accidentally eat some they could make you ill.
You’d probably need to eat about a dozen to suffer any ill effects, but let’s be safe rather than sorry.
You don't need to remove the mushrooms if they don't pose a risk. They'll pop up (literally overnight in some cases), release their spores, and then disappear again. They won't cause your plants any harm. They're just the result of warm weather and damp, nutritious soil.
How to prevent mushrooms from growing in houseplant pots
If the idea of mushrooms in your houseplants freaks you out, for example, if you have a lot of pets and kids running around and you don’t want them to accidentally ingest them, then there are steps you can take that will reduce the chances of mushrooms setting up shop in your houseplants.
The good news is that mushrooms like specific conditions, and if you don’t provide those conditions, they likely won’t turn up.
Since life finds a way, there are no guarantees, but we can try our best.
Mushrooms are just the fruit of the fungi, so the mycelium (the fungi’s root system) will likely still be there. Even if you get rid of it, more will weed its way into your soil.
Keep the top of the soil dry
Mushrooms like damp soil, warm and high levels of nutrients. This is why they’re most common in July and August when it’s hot, humid, and we’re feeding our plants more.
If you keep the top of the soil dry, then you’re making a less inviting home for the mycelium, and whilst they probably won’t be harmed, the chances of them producing a mushroom are lower.
Drier soil also results in less decaying matter and reduces the chances of mushrooms further.
The bonus here is that creating an inhospitable environment for mushrooms also creates an inhospitable environment for fungus gnats, because they feed on decaying matter.
There are a few things you can do to keep the top of the soil dry:
- Bottom water your plants, and remove them from the water before the top of the soil is damp
- Top dress the soil with something that doesn’t retain water, like sand or gravel
- Put the plant in a sunny window so the top of the soil dries quickly – obvs only do this with plants that will appreciate a sunny window, and won’t just burn to a crisp
Mycelium don’t do well in hot temperatures, so you can try heat pads BUT Leucocoprinus birnbaumii seem to be pretty good at adapting to different temperatures, so we can’t promise that this’ll work.
(I can’t promise anything will work – they’re extremely ambitious fungi).
Use a substrate that doesn’t retain much water
Again, don't do this if it's going to interfere with your plant care routine or will cause drought stress to your plants. However, plants like cacti, succulents, and snake plants that prefer not to sit in damp soil, could really benefit from being in a more free-draining soil. You could add grit or sand to your potting mix to ensure that it's drying out quickly.
Don’t do this for plants like Calathea and ferns – you’ll likely just end up underwatering them.
Make sure the plant pot drains well
When we water our houseplants, it’s best to water them deeply and then let them dry out a bit. Ideally, it should take one to two weeks for the soil to need rehydrating, but drainage can massively impact that.
If our plants don’t have adequate drainage then not only do we increase the chance that mushrooms will grow (because the soil is so moist) but we also risk our plants getting root rot because the longer the soil stays wet, the less oxygen there is in the soil.
The less oxygen there is in the soil, the faster the bacteria that produces root rot can reproduce.
The number one easiest way to make sure that your pot is draining well is to make sure it has drainage holes. One is fine for terracotta, but if your pot is made from a non-porous material then it's better to have a few drainage holes.
Don’t use gravel or anything for drainage – all it does is reduce the amount of soil in the pot and create a perched water table.
Sterilise your soil
I don’t recommend sterilising houseplant soil, because it gets rid of good microbes and bugs as well as bad ones, but it will kill the mycelium in the soil and reduce the chance of it coming back.
You can heat your soil in the oven for half an hour at a low heat, or leave it out in the sun on a black bag.
This sounds like it would be a great solution, but unless you change the conditions you were keeping the plant in, more spores will germinate and more mushrooms will grow.
Each Leucocoprinus birnbaumii mushroom can produce millions of spores. We don't know the exact amount, but button mushrooms can produce 3.6 billion spores. Every time you go into the garden centre, spores will likely land on you and you'll end up bringing them home.
As well as heating your soil, you can try pesticides and hydrogen peroxide. They could get rid of the mycelium – apparently systemic pesticides can help – BUT you can compromise the quality of your substrate so I wouldn’t recommend doing that on the off-chance that it gets rid of the mushrooms.
Many organisms can build up resistance to pesticides over time anyway. You don’t want to create a race of superthrips just to get rid of the odd mushrooms.
Remove any dead leaves/decaying matter
Many people leave dead leaves and cast cataphylls on top of the soil, because they break down over time and add nutrients back into the soil.
I wouldn't recommend this, because the decaying matter is the perfect food for the mycelium to feed on. The Leucocoprinus birnbaumii lifecycle is basically fall into pot, germinate, eat, fruit, repeat, so the more nutrients you provide it, the more likely you are to end up with a mushroom or two.
Is the picture of all the cast rubber plant cataphylls mine? Yes. But the top of my rubber plant stays super dry so I don’t think I’ll get any mushrooms.
Remove debris as soon as it drops. Not only will you reduce the chance of getting mushrooms, but you’ll also reduce the chances of getting fungus gnats, which are not fun.
Move the pot away from other plants
This is common advice, but not really suitable for people like me with hundreds of houseplants. However, if you just have a few, make sure that you keep your houseplants spread apart so that when mushrooms do pop up, their spores won’t travel into other plants.
I don't know how far spores can travel, but since they're extremely small and light, I bet it's quite far. Leucocoprinus birnbaumii didn't make it from the tropics to England just to thwarted from spreading in one house.
What not to do to remove houseplant mushrooms
Repot your plant
Not because it’ll damage your plant, but because it’s largely pointless.
Unless you scrub the roots of the plant, you’ll just move the mycelium from one pot to another.
If you do succeed in having a totally sterile, mycelium-free pot, it’s just a matter of time before some spores find their way into it.
A commonly recommended piece of advice is to remove the top layer of soil from your plant, but the mycelium are likely deeper than that and won't be affected. Of course, you can try it, but be aware that a LOT of store-bought houseplant soil can already contain mushroom spores before you open it.
Use fungicides
Again, fungicides will remove the mycelium, but they won’t prevent it from coming back.
There are also reports that Leucocoprinus birnbaumii aren’t particularly phased by fungicides, but I imagine it depends on the brands you use.
I don’t use fungicides because mycorrhizal fungi can be beneficial to the plants, plus good bugs like springtails rely on it to stay alive.
Cinnamon
There is no evidence that cinnamon does ANYTHING to help houseplants.
No studies have even been done on the effects of cinnamon on houseplants. There is evidence that cinnamon has antifungal properties but all of the studies were done in sterile conditions in a lab, and so far, no one has managed to replicate the results in a real-world situation.
Cinnamon won’t harm your plants though, though if you want to give it a go, go ahead. I once tried cinnamon as a top-dressing (just to see if it’d get rid of gnats) and it just grew a layer of mould. The opposite of anti-fungal, it would seem.
Final thoughts
The easiest way to get rid of mushrooms in your houseplants is just to pluck them out and put them in the bin.
It’s incredibly difficult to remove mycelium from houseplant soil, but also, mushrooms don’t crop up that often so it’s not really worth going to all the trouble of doing things like amending your soil mix and exclusively bottom watering just on the off chance that a mushroom turns up.
Leucocoprinus birnbaumii are very difficult to eradicate, and don’t pose much of a threat to us. They’re also not particularly prolific, because they need specific conditions in which to fruit.
