Why Is There Mold in My Compost?

You spot some mold growing in your compost. Is it okay? What to do about it?

When I first started making compost, I was making errors left and right. One morning, I woke up and found a white, moldy substance in my compost. I wasn’t sure what to do and if it was safe.

Sound familiar?

Why Mold Appears

Mold spores are widespread, and air currents transport them. A moist, dark area is the perfect spot for mold spores to settle down and multiply. So, your compost pile is an ideal growing environment for it.

Mold signals good breakdown in your compost. You shouldn’t be concerned because this is all part of the natural and beneficial process that produces the nutrient-rich soil you need for your crop. Make sure you properly mix the mold into the biomass and keep an eye out for other symptoms of difficulty so you can address them before they become a major issue.

Is It Safe?

When you’re new to composting, even a small amount of mold might be alarming. It’s natural to be concerned. Moldy compost, fortunately, is nothing to worry about. It is, after all, a natural occurrence. Mold indicates that your compost is performing its biological function.

However, if the mold starts to take over, it is a sign your compost is out of balance. Normally, simply mixing your pile and pushing the mold deeper into the decomposing material is sufficient.

The mold in your compost pile is unlikely to harm you. However, some people can be sensitive to mold spores, so can consider wearing a mask when handling your compost.

It’s also important to remember that you should avoid ingesting this mold. Mold, unlike edible fungi, can make you—and the wildlife in your yard—sick if it is ingested. But it will not harm your plants. And it is save to consume the produce that grows in soil mixed with compost and mold.

rotting vegetables covered with white mold

Why Is My Compost White?

White fungus-like growth in your compost is most likely Actinomycetes. It may resemble fungus, but it’s actually bacteria, so don’t be alarmed.

Actinomycetes in your compost is good. It is a sign that everything is running smoothly.

Composting is the process of breaking down organic matter to create a beneficial soil amendment for your plants. Worms, insects, and general degradation can all aid with this. Actinomycetes is bacteria that can break down biomass on a cellular level.

How to Tell If Your Compost Is Bad

Your compost pile is working properly if there is no or very little odor. An unpleasant smell is a sure sign that something is not working right.

Whenever something rots, you can smell it. But compost created with the proper proportions of green and brown materials produces very little odor. It should not be smelly enough for you to notice.

If your compost smells unpleasant, it’s most likely because it’s too damp. This will result in anaerobic digestion, which produces toxic, usually sulphureous fumes. What we’re looking for is aerobic action, which is the foundation of any composting process.

A large wooden compost container with rotting apples

How to Fix a Struggling Compost Pile

Air exchange will be restricted if you use a container with limited apertures. It’s critical to keep compost in a well-ventilated space. Turning compost over with a pitchfork or shovel on a regular basis will improve the air flow.

A bad smell can also arise if your compost is too damp. To fix this, add more brown material, such as dried leaves, which will aid in water absorption.

If you’re looking for further answers, check out my article on how to fix common composting problems.

How to Tell When Your Compost Is Finished

When compost has gone through all of the stages of breakdown and no longer produces heat, it is ready to be distributed. The mass should have a strong earthy scent, not like the organic components it was made of.

The finished compost should look homogenous. If you see large chunks or fragments of organic stuff that haven’t broken down yet, it is done ready. Denser materials like wood chips and corn, however, may remain visible, as they take longer to break down.

Jeffrey Douglas
Jeffrey Douglas own a landscaping company and has been in the business for over 20 years. He loves all things related to lawns or gardens and believes that proper maintenance is the key to preventing problems in the first place.
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