Can I Compost Mushrooms: Why This Is Good Or Bad

Can I Compost Mushrooms: Why This Is Good Or Bad

If you’re just starting out on your composting journey, you’re going to constantly have questions about what you can or can’t put in your compost. One question I was asked recently is “Can I compost mushrooms”?

My simple answer to this question is yes, you can put mushrooms into your compost. Even though they’re fungi and not plants, they are still organic matter and will break down just like all your other kitchen scraps.

Should You Cut Up Mushrooms Before Composting?

Just like anything else you add to your compost, mushrooms will break down much faster when they’re cut up rather than thrown in whole.

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However, there’s also nothing wrong with throwing a handful of whole mushrooms in your compost. They will eventually break down along with the other food scraps but it might just take a little longer.

mushrooms are beneficial to your compost

What Are The Benefits Of Adding Edible Mushrooms To Your Compost?

As mushrooms are fungi, they can actually help to speed up the composting process. Plus, they will add valuable minerals to your compost. This is really useful because compost normally doesn’t contain a lot of minerals.

Some of the most valuable nutrients that mushrooms can add to your compost include phosphorus, copper, potassium and selenium. As you would know, these are especially useful for fruiting crops such as tomatoes, cucumbers and capsicum.

Plus, mushrooms also have a fairly high moisture content. This will help to speed up the composting process.

Can You Add Mushroom Compost To Enrich Your Compost Pile?

Mushroom compost sometimes referred to as mushroom soil, can also be a valuable addition to your regular compost bin or pile. Essentially, the mushroom compost that you buy is the spent growing medium used by commercial mushroom growers.

bagging up mushroom substrate

It is commonly known as mushroom substrate as it is the medium used to grow mushrooms. Depending on which brand you buy, it may contain straw, horse manure, chicken manure, peat moss and sphagnum moss. 

This compost is usually sold in bags for use in the garden and is popular for vegetable gardens. 

It does contain mycelium which is like the roots and stems of the mushrooms. Unlike plants, mushrooms do most of their growing underground and the mushrooms that appear above the ground are actually the flower or fruit of the fungi.


What is mycelium?

Mycelium consists of an underground network of fine thread-like filaments that look like roots. These are known as hyphae. The mycelium is actually the vegetative part of the mushroom.

What you see above the ground and what we commonly harvest as mushrooms are just the fruiting bodies of the fungi.

You might be interested to know that mycelium is also the fungus or mold that you can see growing on food stuff like blue cheese. 

The mycelium acts a lot like the roots of plants. The tiny strands travel through the soil secreting digestive enzymes as they grow. These enzymes break down decaying matter and the mycelium absorbs this as food for the mushroom.

All of this activity within the soil, or your compost pile, actually helps to create a healthy environment for plant growth.

For those who love the science of the natural world as much as I do, here’s a timelapse video I found on YouTube that shows the growth of a variety of different fungi in the wild.

Can You Add Mushroom Compost To Your Garden Soil?

can you add mushroom compost to garden soil?

While mushroom compost can be used straight on your garden beds, you may find that some mushrooms will grow as well. In this case, you must carefully identify the mushrooms to ensure they’re edible if you want to harvest them.

Although I absolutely love mushrooms, I wouldn’t be confident enough to harvest any that grow naturally in my garden. I have, however, purchased mushroom kits and grown delicious mushrooms that way,

Then, when the mushrooms are all spent, I’ll throw the remaining compost into one of my compost bins to aid the decomposition of green matter and add valuable minerals as well.

Remember that mushroom compost will also raise the pH level of your soil. So, if you have acidic soil and you want to raise the pH, adding mushroom compost is a good way to do this.

However, if your soil is already alkaline, then you definitely don’t want to add mushroom compost to it. This can be detrimental to acid-loving plants including a variety of different vegetables like radishes and peppers.

You’ll also find that soils that are too alkaline will reduce the nutrient availability to your plant roots. 

In addition, mushroom compost does have quite a high salt content which may not be good for young plant roots.

Can Mushrooms Grow In Your Compost?

It is entirely possible for mushrooms to grow in your compost. Especially, if your composting materials are damp and there’s a fair bit of humidity. This is most likely to happen in an open compost pile.

I have both a static compost bin with a tight-fitting lid and a compost tumbler. I must admit that I’ve never seen mushrooms growing in either of these bins. This is probably due to the fact that the compost is totally dark and not exposed to indirect light.

will mushrooms grow in your compost?

Are Mushrooms Growing In Your Compost Bad?

If you happen to have an open compost pile and find that mushrooms grow in this, it’s not actually a bad thing. In fact, they will probably assist with the decomposition of all the green matter that you throw in your compost.

poisonous mushrooms - toadstools

However, not all the mushrooms that grow in your compost are safe. There are plenty of deadly mushrooms that can appear in your compost pile. While many of these are quite beautiful to look at, you have to be careful if you have children or pets.

In this case, it’s best to remove the wild mushrooms and just bury them in the center of your compost pile. Make sure that you wear gloves when you handle wild mushrooms. 

If you do this, the mycelium will still be present throughout your compost and work to break down the organic materials. However, if you don’t allow the mushrooms to grow, there’s no likelihood of them producing spores that can spread to other areas of your garden.

How Do Mushrooms End Up In Your Compost?

Mushrooms grow from tiny spores. These are very small single-cell organisms that are carried through the air by the wind. Moist, humid conditions are ideal for dispersing mushroom spawn or spores. If these land in your compost pile, you will end up with mushrooms growing there.

What Species Of Mushrooms Are You Likely To Find In Compost?

There could be numerous different species of mushrooms that end up in your compost. It’s an interesting fact that different species of mushrooms feed on different types of decomposing materials.

Here’s a simple chart that explains what different species prefer to feed on:

Types of MushroomsWhat They Feed On
ShiitakeTrees that have just died or freshly cut branches
Oyster MushroomsTrees that have just died or freshly cut branches
Wine Cap MushroomsLeaf litter and decomposing wood chips
Blewits such as Wood BlewitGarden waste and decomposing organic matter
Button, Portabella and CreminiDecomposed compost
oyster mushrooms growing in a tree

Apart from these species of mushrooms, you might also find a whole range of wild mushrooms. This could include poisonous mushrooms. So, you do have to be careful to keep children and pets away from your compost pile.

Can You Stop Mushrooms From Growing In Your Compost?

First, let me clarify that just throwing mushrooms in your compost will generally not cause them to grow. This is because harvested mushrooms will just break down like other organic matter.

It’s only if mushroom spores end up in your compost that you’ll end up with fungi growth.

There are some things that you can do to prevent fungi from growing in your compost. Here are a few tips:

  • Use an enclosed compost bin with a tight-fitting lid so that no light gets in.
  • Ensure you have a well-balanced mix of green waste such as vegetable scraps, coffee grounds and grass clippings and brown waste such as dried leaves.
  • If you have a compost heap, endeavor to turn it on a fairly regular basis as this will break up any mycelium.
  • Add worms to your rich compost as these will tunnel through and break up the mycelium as well.

Frequently Asked Questions

Can you throw cooked mushrooms in the compost?

Yes, both raw and cooked mushrooms can be thrown in your compost.

Should mushrooms be cut up before composting?

It is better to cut up your mushrooms into smaller pieces before adding them to the compost. This is a great way to speed up the decomposition process.

Want To Know More About Composting?

Whether you’re just starting your composting journey or you’re well on your way to becoming a seasoned professional, I’ve written a number of articles about this fascinating topic that you might like to explore.

Final Thoughts

If you’ve ever wondered if you can compost mushrooms, then I hope that you found this article helpful. Mushrooms, whether raw or cooked, can definitely be added to your compost.

In fact, they make a valuable addition and will only help to enrich your compost.

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