Why Is There A Mushroom Growing In My Cactus

A mushroom growing in your cactus pot is a sign that your soil is staying too wet for too long.

The fungus itself isn’t usually attacking your cactus, but it’s a flashing warning light about your watering habits.

If you’ve spotted a mushroom in your cactus, it means the organic matter in the soil is decomposing, which is exactly what mushrooms love to feast on.

In this post, we’ll dig into why there is a mushroom growing in my cactus, what it means for your plant’s health, and how to prevent these fungal gatecrashers from coming back.

Let’s get to the root of it.

Why There Is A Mushroom Growing In My Cactus

The short answer to why there is a mushroom growing in my cactus is excess moisture combined with organic material in the potting mix.
 
Cacti are desert plants that thrive in bone-dry conditions, but the soil you bought or mixed might be holding onto water like a sponge.
 
Mushrooms are the fruiting bodies of fungi that live in the soil, and they only pop up when the environment is damp and rich in nutrients.
 
So, when you ask “why is there a mushroom growing in my cactus,” the real culprit is usually overwatering or a potting mix that doesn’t drain fast enough.
 
Let’s break down the specific reasons behind this fungal invasion.
 

1. Overwatering Creates the Perfect Mushroom Environment

The number one reason there is a mushroom growing in my cactus is that you’re watering too often or too much.
 
Cacti need their soil to dry out completely between waterings, and they can go weeks without a drink.
 
If you’re watering on a fixed schedule instead of checking the soil moisture, you’re likely keeping the roots wet.
 
Mushrooms need constant moisture to grow, so a consistently damp cactus pot is basically a five-star hotel for fungus.
 
Ease up on the watering and let the top two inches of soil dry out fully before you even think about giving your cactus more water.
 

2. Your Potting Mix Is Too Rich in Organic Matter

Another reason why there is a mushroom growing in my cactus is that the soil contains compost, bark, or peat moss.
 
Many commercial potting mixes are packed with organic material that holds water and breaks down over time.
 
Mushrooms feed on this decomposing organic matter, so a rich soil mix is an open invitation for them.
 
Cacti actually prefer a gritty, mineral-based mix like coarse sand, perlite, or pumice that doesn’t hold much water.
 
If mushrooms keep appearing, it’s time to consider repotting your cactus into a leaner, faster-draining medium.
 

3. Poor Drainage Traps Water Around the Roots

Sometimes the mushroom growing in my cactus is caused by a pot without proper drainage holes.
 
If your cactus pot is sealed or sitting on a saucer with standing water, the soil never gets a chance to dry.
 
This trapped moisture creates the exact conditions mushrooms need to sprout.
 
Make sure your pot has at least one drainage hole at the bottom, and never let the cactus sit in a puddle of water.
 
Lifting the pot after watering can tell you a lot—if it feels heavy and waterlogged, you’ve got a drainage problem.
 

4. High Humidity Around the Plant

If your cactus lives in a humid bathroom or a closed terrarium, that’s another reason why there is a mushroom growing in my cactus.
 
Mushrooms love humid air, and your cactus’s pot can become a microclimate for fungus.
 
Even if you’re watering sparingly, surrounding humidity can keep the soil surface moist enough for mushrooms to fruit.
 
Move your cactus to a spot with good airflow, like a sunny window in a dry room, to discourage fungal growth.
 

Is The Mushroom Growing In My Cactus Harmful?

The mushroom itself is rarely harmful to your cactus, but the conditions that caused it can be deadly.
 
The fungus is just decomposing organic matter in the soil, and it won’t directly attack the cactus roots.
 
However, the constant moisture that brings mushrooms also encourages root rot, which is the most common killer of cacti.
 
If you see a mushroom growing in my cactus pot, check the base of the cactus for soft, mushy, or discolored spots—those are signs of rot.
 
So while the mushroom won’t hurt your cactus, the reason it’s there definitely will if you don’t fix the moisture problem.
 
And don’t worry about the fungus spreading to your other houseplants—this particular mushroom type is usually specific to the pot it’s in.
 

How To Get Rid Of Mushrooms In Cactus Soil

Getting rid of the mushroom growing in my cactus is simple, but keeping it gone requires changing your care routine.
 
Here’s how to banish those fungi for good.
 

1. Remove the Mushroom and Topsoil

First, carefully pluck out the mushroom and scoop away the top inch of soil where the fungus lives.
 
This removes the visible spores and some of the fungal network before it can spread further.
 
Dispose of the soil in the trash, not in your compost pile, to avoid reintroducing the fungus.
 

2. Let the Soil Dry Out Completely

Stop watering your cactus for a couple of weeks or until the soil is bone dry all the way through.
 
You can even move the pot to a warmer, sunnier spot to speed up the drying process.
 
The lack of water will kill the fungus and prevent any new mushrooms from sprouting.
 
When you resume watering, use the soak-and-dry method, which means watering deeply but then letting the soil fully dry before the next soak.
 

3. Repot With A Gritty Cactus Mix

If mushrooms keep coming back, repot your cactus into a fresh, gritty mix specifically designed for cacti and succulents.
 
You can mix regular potting soil with equal parts perlite and coarse sand to improve drainage.
 
Before repotting, inspect the roots and cut away any black or mushy sections with a clean knife.
 
Let the repotted cactus sit dry for at least a week before you water it again, giving any damaged roots time to heal.
 

So, Why Is There A Mushroom Growing In My Cactus?

So, why is there a mushroom growing in my cactus?
 
A mushroom growing in my cactus means your soil is too wet, too rich, or too poorly drained for a desert plant.
 
While the mushroom won’t harm your cactus directly, it’s a clear sign that overwatering or bad drainage is threatening your plant’s roots.
 
By removing the mushroom, drying out the soil, and repotting into a gritty mix, you can keep your cactus healthy and fungus-free.
 
Always remember that cacti thrive on neglect—less water and better drainage are the keys to preventing this issue from ever happening again.
 
Now you know exactly why that mushroom showed up and what to do about it.