Skip to Content

Can Mulch Get Moldy? (And Can Mold Hurt Your Plants?)

Can Mulch Get Moldy? (And Can Mold Hurt Your Plants?)

Share this post:

Disclaimer: Some links found on this page might be affiliate links. If you click an affiliate link and make a purchase, I might earn a commission. As an Amazon Associate I earn from qualifying purchases.

It’s a bright, sunny morning, and you’re taking a tour through your backyard. You see your flower beds blooming and thriving.

Yet, out of the corner of your eye, you notice a white patch in the middle of your garden bed. After closer inspection, you realize that it’s mold growing straight off the mulch.

At this point, you’re left wondering, can mulch get moldy? If that’s the case, we can help.

In this article, we’ll walk you through everything you need to know about moldy mulch. We’ll cover the drawbacks and what you can do to repair the organic compound.

Can Mold Grow on Mulch?

The simple answer to this question is yes, under specific conditions, mulch can get moldy. To help you understand this, let’s take a look at the composition of the fertilizer.

It’s a combination of dead leaves, straw, hay, bark, wool, and animal manure. As you can tell, these materials are all organic.

That means bacteria can feed on the mulch and break it down into nutrients for your plants. Although, these aren’t the only microorganisms that get an invitation to your flower beds.

There are tons of other pathogens that can make their way into the soil, like fungi. However, under normal circumstances, these microorganisms can’t multiply or grow.

That’s unless the moisture content of the mulch is incredibly high.

This creates the perfect environment for fungal infestations. Sadly, that leads to mold.

Why Does My Mulch Get Moldy?

There are three main factors that fungi need to thrive. These are:

  • Food source
  • Moisture
  • Warmth

The mulch itself provides the nutrition for the fungi. Plus, as bacteria break down the fertilizer, they generate heat.

So, the only missing element is moisture.

As soon as spring and summer come around, the humidity in the air will rise. This will cause soil to retain more water.

When that happens, it creates the perfect breeding ground for fungi.

How to Identify Moldy Mulch?

By now, you should know that moldy mulch is a result of a fungal infection. Yet identifying the culprit can be a little tricky.

That’s because there are many types of fungi that can cause the issue. Each one will lead to different symptoms and has distinct physical characteristics.

So, before you can treat the disease, you should be able to identify the infection.

Moldy mulch can present in a few unique ways. For starters, the first symptom people notice is discoloration.

Mold can change the color of the mulch. It can turn yellow, white, brown, black, or even green.

Other than that, there’s usually a texture shift. Normal mulch is a bit grainy and coarse.

Yet, moldy mulch is softer and has a fuzzy surface.

Can Mold Spread from Mulch to Other Areas?

When you first see mold on mulch, you assume the problem only affects your flower beds. Unfortunately, that’s not the case,

That’s because mold can spread from one area to another quite rapidly.

For instance, heavy rainfall can move fungal spores from one location to another. The same applies to a strong gust of wind.

Moving on, animals and insects also play a part. If a critter touches the mold with its limbs, it can spread it all over your backyard.

Finally, if gardeners aren’t careful, they can have a hand in spreading the infection. Just shifting the mulch around to dig it up can send spores flying in every direction.

That’s why you need to get rid of mold as soon as possible.

Will Moldy Mulch Harm Plants?

While mold can be unsightly, most of the time, it’s not harmful to plants. That’s because the fungal infection can’t spread from the mulch to the florae.

So, your flowers should still be able to bloom without any issues.

Yet, mold can give off an incredibly unpleasant odor. It’s a little musty with a hint of earthiness.

This won’t affect your plants, but it’ll make enjoying an afternoon in your backyard tough.

Moving on, as we mentioned, the fungi will feed on the mulch to multiply. That means there will be fewer nutrients in the soil for your plants to soak up.

Lastly, if the fungal spores manage to spread, your moldy problem may get out of hand.

So, you can use moldy mulch in your garden, but it’s not a good idea.

Can You Fix Moldy Mulch?

If you want to get rid of moldy mulch, you’re in luck. There are a few simple steps you can follow to resolve the issue in a flash.

First up, you should start by removing any visible traces of the mold. To do that, you’ll need a garden shovel.

Dig out any discolored areas and make sure to remove as much of the fungi as possible.

After that, spray a little vinegar directly onto the mulch. While you do this, make sure you avoid your plants.

That’s because vinegar is acidic, and it can damage the florae.

Other than that, you can choose to spray your flower beds with a fungicide. It’s a chemical that attacks microorganisms and stops them from growing.

As you get rid of mold, it’s crucial that you wear safety gear. That includes gloves, masks, and even safety goggles.

This will prevent the fungal spores from landing on you as you clean out the mulch.

Are Fungicides Harmful to Plants?

Fungicides specifically target fungal spores and stop their germination. However, as they do that, they can cause harm to your plants.

The chemical will seep into the soil and cause phytotoxicity. That means it’ll get rid of all the beneficial plants around it.

That’s why it’s incredibly crucial that you don’t overuse fungicides. You have to read the instructions on the label carefully and ensure you apply the proper dose.

Plus, it’s never a good idea to water a flower bed after you spray fungicides. Otherwise, the water will carry the chemical and spread it all around the soil.

How to Prevent Mold From Growing on Mulch

Getting rid of mold isn’t all that challenging. Yet, the process can be exceptionally tedious.

So, if you’d rather skip the hassle, it’s a good idea to take measures to prevent the fungal disease before it starts.

Luckily, there are a few things you can do.

For starters, it’s best to keep mulch as dry as possible. This is a little tricky to do, but there are a couple of tips that can help.

For example, try to apply thin layers of mulch. This will prevent water retention and make keeping the area dry easier.

Other than that, only water your flower beds when the mulch is dry to the touch.

Moving on, if this sounds like too much work, you can opt for cedar mulch. This is a specific type of organic compound that can resist fungal infections.

Final Thoughts

Can mulch get moldy? Simply put, yes, the fertilizer is susceptible to fungal infections. That’s because mulch can provide warmth, moisture, and nutrients to fungi.

Moving on, the mold can present in a few different ways. That includes yellow, white, or brown patches.

Plus, it usually has a fuzzy texture.

The fungal infection shouldn’t be harmful to your plants. So, you can use moldy mulch, but it’s not the best idea.

Share this post: