Mushrooms Growing In My Compost Bin? Good or Bad? Should I Worry?

Mushrooms Growing In My Compost Bin? Good or Bad? Should I Worry? Have you ever wondered what that white substance on your compost pile is? I guess you might have thought what a gross aspect your compost pile has. Whereas actually, this is quite normal. They're mushrooms. Yes, a mushroom is growing in your compost bin!

Now, why are mushrooms mentioned among typical compost problems? Well, though the production of mushrooms is typical in some decomposing processes, sometimes they might indicate something else. For more on this, don't miss Composting Problems: Types and How to Deal With Them.

Read through to understand why you have mushrooms, which ones can be easily found, and their function (or threats!).


Mushrooms in your Compost?

Fungi or mushrooms? Are they the same? Actually, all mushrooms are fungi though not all fungi are mushrooms. Good point. Some fungi do produce these caps called mushrooms which are, basically, like flowers growing from a plant. It’s important that you know that many mushroom-producing species of fungi are important decomposers, so that’s great news for your compost pile!

If you have mold on your compost, organic materials are breaking down. The presence of mold on your compost is totally a good thing, so don’t worry. They are transforming your organic waste, basically, to turn it into rich soil.

Let’s see the typical “visitors” you can find in your compost pile:


What's mold? What should I do if I have mold in my compost? Should I worry about mold on my compost? The presence of mold means mushrooms growing in my compost? Don’t worry; having mold in your compost is a good sign most of the time. Molds are a type of fungus it might appear on your heap, meaning microbes are doing their job. If you see mold in your compost pile, it means full decomposition, and it’s not dangerous as long as you mix it properly.


Here is what you need to know: How to make a Compost Pile? All you need to know about it

What Does Compost Mold Look Like?

Just think about it. Anything that can decompose will ultimately have mold on it. Bread, fruits, veggies, or food left in the fridge can probably develop this sickening mold. The occurrence of mold is more typically present in cold compost rather than hot because mold doesn’t feel ok in hot temperatures, and it doesn't grow.

White or green mold is the most common in a compost heap. The white one is rather harmless but can indicate that something is wrong in your compost pile. Be careful if it smells bad because this means anaerobic bacteria are in your pile, and we don’t want this. You need to encourage aerobic bacteria instead.

Types of Mold

Molds look like cotton. Their different colors depending on the food they’re “eating” and on climate:

  • Green Mold: this is the most common you may find in compost. It typically appears in compost piles which have a lot of material.

  • White Mold: this is my favorite. When you see white mold in your hot compost pile, it means decomposition is going on well! It feeds from wood particles.
  • Pink Mold: this is the one you should avoid. You’ll find pink mold if you throw cleaning products in your compost pile. You may accidentally throw soapy water or detergent, so the pink mold may probably appear. Cleaning substances kill the organisms working in the decomposition process.

Types of Fungi In Your Compost

  • Toadstools: a toadstool or mushroom is the fruiting body of a fungus. When the heap cools down, these mushrooms will appear to start breaking down cellulose. Most fungi produce their fruiting bodies in autumn mainly.
  • Dog Vomit Fungus (“Slime Mold”): the name just sounds gross. But you can find this in your compost pile, and it’s considered a good fungus. They eat microorganisms found in your compost material and are useful in the decomposition process and cycling of nutrients.

What Is Actinomycetes: Fungus Growing On Compost

Well, though it might sound like a tough word to learn, it’s important that you know what it means. Actinomycetes are fungus-like bacteria playing a big role in the decomposition process in your compost pile. Their presence is a sign of an imbalance of green and brown materials though in manure compost, for example, it might be a good thing (successful decomposition).

If you want to recognize this type of bacteria in your pile, you’ll see a grayish substance that looks like a cobweb, and it has an earthy smell typical of good compost. So, it’s key that you maintain a good environment for this bacteria to grow. Moist the soil (not too much!), reduce pH levels, and add organic material because it’s actinomycetes’ dinner! Also, keep your pile aerated, and you’ll get a perfect dark earthy compost.

Benefits of Mushroom Compost

As said before, having mushrooms growing in your compost is good news. What’s more, you can add mushrooms to your compost pile. The use of mushroom compost is highly beneficial. It makes your soil richer, and it’s a perfect nutrient supplier. Plus, it improves the absorption of water in the soil. And the most important benefit, mushrooms are the ultimate composter, breaking down organic material and thus accelerating the decomposition process.

Check this out: How to Choose the Best Indoor Compost Bins? The Ultimate Guide

Now, there’s a lot you can learn about growing your own mushrooms in your compost pile. No more mushrooms from the grocery. Take advantage of your pile and try this out!

These are called secondary decomposers mushrooms because they appear after the fungi at the top of the rot chain have already done their jobs.

In case you decide to have mushrooms growing in your compost, keep these tips in mind to be successful:

  • It’s important that you aerate and mix your pile.
  • Spray water and turn the pile
  • Nitrogen and gypsum supplements are added to the material and turned again.
  • Aerobic fermentation starts here. Microorganisms start growing and reproducing.
  • Heat, ammonia, and CO2 are released during this phase.
  • Now is the time when mushrooms develop thanks to the chemical nature of the raw materials converted by microorganisms, plus heat and heat-releasing chemical reactions.
  • This is the perfect food source for mushroom development and growth.
  • Keep in mind that for mushrooms to develop, you need: oxygen, moisture, nitrogen, and carbohydrates. That’s why it’s so important that you add water regularly and aerate and turn your compost pile.
  • When finishing composting, it’s important to carry out pasteurization to kill pests and insects. Also, it’s necessary to get rid of all the ammonia formed in the first stage of the composting process.

You may be interested: All the Tools Needed for Composting and Build your Worm Farm.


Among the most typical types of mushrooms to grow on your compost, you have:

  • Wood Blewit: this is a beautiful and colorful mushroom that will make your compost pile really attractive with shades of pink, blue, and lavender. It’s a dense mushroom characterized by an earthy flavor. This mushroom loves decayed organic matter. It takes a rather long to grow one of these, but it’s worth waiting.
  • Shaggy Mane: aka shaggy inky cap, this special mushroom takes a little bit more time and needs attention. It tastes like asparagus. The perfect conditions to grow them is in an ammonia environment of an active compost pile. However, once the pile reaches the hottest peak, these mushrooms normally die.
  • Wine Cap Stropharia: These nutty-flavored and crispy mushrooms grow on wood chips or sawdust, or straw and are great litter decomposers.

When to Worry About Fungi

Watch out in case you have this type of fungus:

  • Honey Fungus: it’s harmful to roots and would kill perennial plants. It smells strongly of mushrooms and infests your compost, thus killing your plants when you use it.
  • Artillery Fungi (Sphaerobolus species): these are responsible for those black spots on plants and around your house. They shoot spores high in the air, so they really invade your area.

Remember that toadstools and fungi, in general, thrive in humid atmospheres. They grow from fine threads of fungus called mycelium, which is present in any compost pile. Also, they love warm and wet environments to produce mushrooms.

If you don’t want mushrooms growing in your compost pile, make sure you have a good ratio of greens and nitrogen sources in your compost pile. Be sure you turn your pile regularly to avoid their presence. Also, keep a good balance between cellulose and nitrogen (food scraps, for example) and frequently aerate with a pitchfork or tumbler.

In A Nutshell

Having mushrooms growing in your compost can not only be a good thing as your pile is working well, but it’s also a great opportunity to start a new challenge: growing your own mushrooms!

Whether you have mold or any type of fungi on your compost heap, it means basically that microorganisms are doing their job. You’re adding the precise amount of water it needs, and the mixing is appropriate. There’s a variety of mushroom species you can grow if you follow the right steps and keep an eye on the pile frequently. It may take extra time, but it’s worth it.

Now, fungi and bacteria are among the most frequent compost problems people face when they start composting. If these mushrooms growing in your compost or mold on top of the pile produce a bad smell, you can always change this by keeping a balance of the ingredients you’re adding.Learn more about this topic on Smelly Compost? How to Control Bad Smell on Your Compost

Remember that though mold is frequent in any decomposition process, you can get rid of it by changing ingredients, techniques, and the quantity of water you add. If your compost is too wet, mushrooms and mold will flourish. Learn the reasons for this in Compost Too Wet? Reasons Why and Tips to Fix a Soggy Compost

The material you add can always be the perfect dinner for mushrooms, so keep an eye on this and make a good selection of ingredients to get that earthy dark fresh soil out of your compost pile.

Veronica Prez

A little person trying to be part of a big change. Compost lover. Editor at Sustainable Warriors.

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