Mold In Compost (Should You Be Worried?) (2024)

It can be a bit of a shock!

Finding mold growing in your compost pile isn’t the most pleasant surprise.

If you’ve discovered something moldy in your compost, you’re probably wondering whether this is good or bad?

And if your compost has mold, can you still use it? Should you try to prevent it?

And what about adding moldy organic material to your compost? Can this be done?

Phew! So many “moldering” questions 🙂

I’ll explain everything you need to know about mold and compost in the following article…

Moldy Compost

Adding moldy organic material to your compost is not a problem. It adds beneficial decomposing microorganisms to the mixture. Likewise, it is not a problem if your compost pile has developed mold. But you should turn the pile regularly to mix it evenly throughout the compost. Also, use less water to reduce mold.

As gardeners, we sometimes need to experiment and tweak our garden processes to get the most value from them, and composting is no different. However, when our composting efforts don’t turn out the way we expect, we wonder how to proceed.

Mold in compost is one of those occurrences. It’s a bit of a dilemma. Because mostly, we’re taught that mold is a bad thing.

This raises the question of whether composting moldy material is acceptable. Or whether we can use compost from our pile that has developed mold.

Is Compost Supposed To Mold?

So should there be mold in my compost? The first time I discovered mold in my compost, I freaked out a little, and I wasn’t sure what to do.

Today, as a seasoned composter, my advice is, “don’t panic”!The fact is, it’s perfectly normal for compost to have some level of mold.

However, remember that excessive amounts of mold can upset the balance of the compost.

Mold develops in warm, moist conditions (sounds a lot like the environment in your compost pile… Right?!). Mold is a natural part of the decomposition of all that organic matter!

So don’t worry!

What about Moldy Food? Can it be composted?

Mold In Compost (Should You Be Worried?) (1)

Composting moldy food is perfectly fine. In fact, it is one of the best ways to recycle spoiled food and recover something valuable for your garden.

Mold in compost is beneficial to your compost pile’s decomposition process. Adding moldy food scraps from your kitchen can help kickstart or accelerate composting.

Even if you do not add mold directly to your compost, it will develop naturally in the pile’s warm, damp environment.

Why Does My Compost Have Mold?

Your compost has mold because it is a warm, humid environment that is perfect for developing fungal growth. Tiny mold spores settle on the decaying material in the compost pile, which has ideal conditions for them to grow.

In my experience, the higher the humidity in the compost pile, the more likely the pile is to develop visible fungal or mold growth.

But Is Mold Good For Compost?

Generally speaking, a certain level of mold in your compost is good for the decomposition process. However, mold in your compost becomes a problem when there is an imbalance and mold growth becomes excessive.

Some molds can produce dangerous toxins called mycotoxins, which are detrimental to your plants, and possibly to you if you eat plants that have absorbed these toxins!

When the mold is prolific, it’s difficult to distinguish good mold from bad, so you should never allow the mold growth in your compost to grow unchecked.

Turn your compost more regularly and stop watering. Aerating the pile will help dry it out and should reduce fungal development.

Is Moldy Compost Bad For Plants?

Mold In Compost (Should You Be Worried?) (2)

Mold and fungi are a natural part of the decomposition process and do not affect compost quality. In fact, their presence is beneficial for breaking down tough organic materials like the cellulose found in woody substances.

It’s normal to find fungi and actinomycetes during the composting process. They work at medium temperatures, and you’ll often see them around the fringes of the pile (they leave the hot center of a pile to the thermophilic fungi).

If you spot some white or grayish threads that look like cobwebs, these are actinomycetes.

What To Do If My Compost Has Mold

While there’s no way to completely prevent mold, you can minimize its growth by turning your compost pile regularly.

I have found that turning the compost every 2 to 3 days is an effective measure to keep the mold growth under control.

Turning the compost aerates the mix and distributes the moisture and mold evenly throughout the compost. You can do this more efficiently withan aeration tool like this(Amazon). This prevents a large amount of mold growth in a single area of your compost.

Aeration is especially needed if you find green-looking mold in your compost. This is the result of oxygenless composting! Believe me… you’ll know it when you find it because of the nasty smell!

How To Get Rid Of Mold In Compost

Mold means that your compost heap is healthy, so it is not a cause for stress unless you see the mold begin to reproduce prolifically.

Simple compost pile management is the best way to manage and reduce mold in compost. In most cases, excessive mold develops in compost piles that have been neglected and not managed correctly.

The best way to reduce mold in your compost is to take the following steps:

  • Turn the compost regularly. This is the best method to control mold development in your compost. Most recommendations are to turn the compost once a week, but turning every 2 to 3-days will help disperse mold.
  • Reduce the moisture content. The best way to reduce moisture content in a compost pile is to add more “brown” material to the pile. The dry, woody material absorbs some of the moisture in the compost, reducing the overall humidity and, thus, mold growth.
  • Turn up the heat. Suppose you regularly struggle against excessive mold in your compost. In that case, it may be due to the high humidity in your local climate. Hot composting in these locations will lower the mold development in the compost pile.

Compost Mold Dangers & Precautions

Mold is a small fungus that thrives in warm, moist locations and especially likes decaying organic matter. Although some types of mold can cause problems, they’re not necessarily dangerous.

The main thing to keep in mind is balance. If your compost is unbalanced, you’ll need to adjust it. If it’s too mushy or too damp, it’s a sign that it’s time to adjust it.

Three main mold types develop in compost:

  • green mold
  • white mold
  • pink mold

White and green mold development in compost is natural. Still, thegrowth of pink mold indicates the presence of potentially toxic mold.

Any pink mold on your compost should be scraped off and discarded. Green and white mold are beneficial mold types, and the compost can simply be turned to distribute the mold evenly through the pile.

Those are the precautions for your compost, but what about your personal protection when handling your compost?

For a start, always wear gloves.These rubber-coated gardening gloves are a good option.(Amazon)

Mold in itself is not toxic, butthe sporesthat the fungi give off as part of their reproductive cycle can pose problems for people with respiratory problems such as asthma. Certain people with chest or allergy concerns are more susceptible to mold spores than others.

People with this type of medical history should wear a dust mask when turning the compost or collecting compost to use in the garden.

Conclusion

Mold development in a compost pile often indicates healthy decomposition. However, the compost pile should be turned frequently to evenly distribute any fungal growth through the mixture and prevent it from increasing out of control.

In my experience, simple compost maintenance, such as controlling the moisture level and aerating the compost regularly, will prevent most mold problems in your composting process!

Mold In Compost (Should You Be Worried?) (3)
Mold In Compost (Should You Be Worried?) (2024)

FAQs

Is it okay if your compost has mold? ›

Having some mold in your compost is a natural and healthy thing. In fact, mold in your compost is proof that the system is working as it's supposed to. In addition to the bacteria that break your food down, mold (a type of fungus) also does this critical work.

Can you put moldy bread in compost? ›

Yes, you can definitely compost moldy bread. Mold is probably best avoided as food, but your compost pile will love it! Composting moldy bread is a good idea since mold speeds up decomposition.

What is the white stuff in my compost pile? ›

Saprophytic fungi decay dead organic matter and do not attack or damage living plants. It is common to see white mycelia (the thread-like filaments of fungal growth) when organic mulches are dug into (you also see them in compost piles). There is no need for concern or treatment for control.

Can you compost plants with mildew? ›

Should be no problem at all. Powdery mildews only survive on a living host and the composting process will kill the fungus as well as the plants. Not many plant pathogens survive the process.

Is moldy fruit ok for compost? ›

Mold is a term we use for a class of fungi. Go ahead and add moldy materials to your compost pile." Los Angeles County Public Works, while moldy veggies tend to be fine for worms to digest, moldy fruit and bread could cause the worms to become sick and possibly die.

What is the orange mold in my compost? ›

Thanks for your comment about the orange blob of mould in your compost. Firstly don't worry; they are harmless. These orange blobs, sometimes referred to as dog vomit, are actually slime mould! The orange fungus is a species of slime mould known scientifically as physarum polycephalum.

Can you put rotten fruit in compost? ›

Yes and yes. Veggies and fruits are the quintessential compostable foods. You can compost them in any form: scraps and peels, raw or cooked, and even when rotten. Before you toss, make sure you're not wasting these completely edible food scraps.

What fruit should not be composted? ›

Some fruits and vegetables that you should compost with caution are those with high acidities, such as citrus fruits, pickles, and tomatoes. The acid content of these foods can kill the good bacteria in your compost pile and slow down its decomposition.

Can I put banana peels in my compost? ›

Yes, you definitely can. Bananas are organic matter and so are their peels, so feel free to include these in your compost materials. Your garden and the environment will thank you!

What is the GREY fuzzy mold in my compost? ›

Don't worry about this at all. It's just a nice fuzzy mold and it is one of hundreds of species of living things that will get to work breaking down your food waste. The only time you need worry - and even then don't fret too much - is when using Bokashi.

What does a healthy compost pile look like? ›

While it may not always look appealing depending on the stage, it should essentially feel earthy or loamy. A rotten smell will likely accompany a slimy texture. Piles also commonly feel dry or ashy if they aren't watered sufficiently or are becoming too hot. The task of watering seems daunting.

What are the symptoms of contaminated compost? ›

Herbicide damage from contaminated compost or soil mix is caused by growth regulator herbicides. These herbicides more often affect broadleaf plants. Look for distorted or cupped leaves. The damage occurs in new growth, including the ends of the shoots.

Can I put corn cobs in my compost? ›

You absolutely can compost corn cobs, since they are biodegradable and keep them out the landfill. When you add the corn cobs to your compost, the nutrients that are locked in the cob will release over time and provide a delayed supply of nutrients for your soil.

Can you put moldy cucumbers in compost? ›

While the mold that forms on most vegetables is usually ok for composting, those that form on fruit and bread might be problematic, especially if you have a worm bin. Many compost bins thrive using earthworms, which can help make the soil even more fertile and aid in decomposition.

What flowers should not be composted? ›

Types of Flowers or Flower Parts NOT to Add to Compost

Look for diseased or infested plant parts as well as those that are poisonous to pets. The diseased and infested plant parts are self-explanatory – you risk spreading the pathogens and pests if you add them to your compost.

Is mold bad for compost worms? ›

Mold is not directly harmful to the worms. In fact the worms need the mold to break down the food waste. The worms then eat the mold itself and the smaller pieces of food matter. Without mold you will still have the piece of bread lying in the bin for quite a while, and your worms will not be able to process that!

Can I put moldy food in the green bin? ›

Yes, put it into the compost bin. Mold is actually an agent of composting. Moldy food is food that has partly composted.

How often should I turn my compost? ›

This turning process ensures that oxygen levels do not drop low enough to kill the good organisms and grow pathogens. NOP guidelines require compost to be turned a minimum of five times within a 15-day period, during which time the temperature must be maintained between 131- and 170-degrees F.

How to fix wet compost? ›

If your compost heap is too wet, dig it out completely, then turn the ingredients to incorporate more air before restacking. Add dry materials into the mix to get a balance of greens and browns, improve drainage and prevent the compost from clogging up again.

Top Articles
Latest Posts
Article information

Author: Ray Christiansen

Last Updated:

Views: 6329

Rating: 4.9 / 5 (49 voted)

Reviews: 88% of readers found this page helpful

Author information

Name: Ray Christiansen

Birthday: 1998-05-04

Address: Apt. 814 34339 Sauer Islands, Hirtheville, GA 02446-8771

Phone: +337636892828

Job: Lead Hospitality Designer

Hobby: Urban exploration, Tai chi, Lockpicking, Fashion, Gunsmithing, Pottery, Geocaching

Introduction: My name is Ray Christiansen, I am a fair, good, cute, gentle, vast, glamorous, excited person who loves writing and wants to share my knowledge and understanding with you.