How to Get Rid of Fungus in Mulch | Orange, Yellow, Artillery

Many home gardeners rely on mulch to improve soil conditions, grow healthy plants, and create attractive natural landscaping. However, mulch can sometimes attract unsightly and even dangerous fungi into your garden. 

Fortunately, there are plenty of ways that you can safely and effectively remove fungus growing in your mulch beds. In this article, I’ll show you how to get rid of fungus in mulch and keep your yard looking its best. 

How To Get Rid of Mulch Fungus

It can be tough to remove established fungal colonies after a period of unchecked growth. The best way to handle mulch fungus is to tackle the issue as quickly as possible. As soon as you see the first signs of growth, you should take steps to eliminate any further growth and prevent future colonies from sprouting.

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Remove Fungi by Hand

One of the simplest ways to get rid of mushrooms or eliminate mulch fungus is to remove the colonies by hand. This method works best with fungi that produce mushrooms, as these fruiting bodies are easy to spot and handle. 

After removing fungal bodies, you should scrape away the top layer of mulch in any affected garden beds. Otherwise, live fungal material such as hyphae may remain underground and sprout again, leading to future infestations. 

When removing fungi by hand, always make sure to wear protective gear. While the majority of mushrooms and other common fungi are safe to touch, some may contain mild skin irritants or trigger an allergic reaction. 

It’s always best to be on the safe side and wear long sleeves, long pants, boots, and thick gloves when removing mulch fungi by hand. You may also want to wear a mask or respirator to protect yourself from airborne spores. 

Adjust the Mulch pH

Acidic mulch can attract the growth of fungi such as yellow fungus and artillery fungus, among other species. According to Iowa State University, fungi grow best in wet, warm conditions with a low pH, meaning that you can kill fungi and inhibit future growth by raising the pH of your mulch.

One of the best ways for gardeners to de-acidify soil and mulch is to add lime, which is basic enough to raise pH levels. Hydrated liquid lime works quickly and effectively but you can also find slow-acting pellets that reduce the risk of over-liming. Wood ash also works well to raise mulch pH.

When adjusting pH to combat fungus, don’t forget to consider garden plants. While some hardier species can tolerate changes in soil pH, many are sensitive to environmental changes and may experience stunted growth, illness, or even death. Be careful when adding lime or wood ash, and avoid sprinkling too close to root systems. 

Use Fungicides

Fungicides offer a fast, easy, and effective way to control fungal infestations. You can find chemical fungicides at your local gardening store but keep in mind that these can contaminate soil and may be harmful to local plant and animal life.

Organic fungicides are typically the most eco-conscious choice when combating mulch fungus. It’s best to look for options with all-natural and biodegradable ingredients. Even so, be careful where you spray, as some fungicides may stunt plant growth. 

Always protect yourself when spraying fungicides, whether organic or not. You should protect exposed skin as well as your eyes, nose, and mouth. It’s a good idea to wear safety glasses or goggles alongside a mask or respirator as you work. 


While it might sound like an unusual remedy, many gardeners swear by the cornmeal removal method for mulch fungus. Cornmeal contains anti-fungal components that work to kill live growth and may even help to prevent future infestations.

To treat a fungal colony, mix cornmeal with water and spread it across the problem area in a thick paste. You should add about one cup of cornmeal to a gallon of cold or room-temperature water for the best results. 

Baking Soda

Baking soda is another unlikely remedy for mulch fungus that’s both easy and cost-effective. Sprinkling baking soda on the ground raises the pH of the surrounding mulch, creating an inhospitable environment for acid-loving fungal colonies. 

Mix just two teaspoons of baking soda in a gallon of water, making sure to dissolve thoroughly. Pour the mixture on the mulch around a fungal infestation and allow it to soak in. Though it may take a few hours to a few days, the alkaline environment will eventually kill the fungal growth. It will also help to discourage new spores from sprouting. 

What Causes Fungus in Mulch?

While mulch doesn’t cause fungus, it can attract fungal growth under the right conditions. As long as the mulch is kept damp, the fungus will have no problem thriving in warm enough weather. During the reproductive phase, spores are likely to settle on a freshly watered bed of mulch.

Many species of fungus live off rotting organic components, such as decaying wood, while others eat bacteria growing within the mulch bed. As long as there is a hospitable environment and plenty of food, it’s perfectly natural to see fungal growth in your mulch.

During the life cycle of fungi, a fertile fruiting body releases spores into the air. These spores can travel far distances from the parent plant before settling, meaning that a fungal infestation in a neighboring yard can easily end up in yours. 

Once a spore settles, it either lies dormant in wait of more favorable conditions or it begins to sprout. Spores that settle in mulch are often in a good position to sprout, grow, and reproduce, thus spreading to other areas of your garden.

Is Fungus in Mulch Bad for the Garden?

Fungi can be beneficial for your garden’s ecosystem, helping to drive decay and reintroduce nutrients into the ground. As fungus digests mulch, it releases minerals that can help to improve soil fertility and improve local plant growth. 

In most cases, fungus in mulch is beneficial for your garden. However, it may still be wise to treat an infestation before it grows out of hand. While most fungi are safe for plants, the same can’t be said for humans and animals. 

Is Fungi in Mulch Harmful to Pets or Humans?

While most common garden fungi are safe to touch, they may not be safe for consumption. It can be a challenge to tell edible mushrooms apart from toxic species, especially for young children and pets. What’s more, many fungus varieties come in bright, vivid colors that can attract the curiosity of hungry family members. 

Even though fungi in mulch might be beneficial for your garden, it’s good to remove any growth you see as soon as possible. Doing this will prevent any accidental ingestion that may lead to indigestion, poisoning, or even fatality. 

Can You Prevent Mold From Growing in Mulch?

Even if you know how to get rid of fungus in mulch, prevention is always the best option. The best way to prevent new growth is by creating an inhospitable environment for mold spores. They need a moist, stable environment where sprouts can take hold.

Adjusting your watering schedule may help to prevent mold growth in your mulch. Since fungus prefers a damp environment, try to only water plants as necessary and give mulch a chance to dry out between irrigation sessions. It’s best to water plants early in the morning, so that excess moisture has a chance to evaporate.

Raking your mulch beds regularly can also deter new fungal growth. It prevents spores from taking hold while also keeping the underlayer of your mulch dry and aerated. You should take special care to rake in the days following a rain shower to encourage fast surface evaporation. 

Identifying Fungi Growing In Mulch

Knowing how to identify different types of mulch fungi can help you figure out the best way to treat your garden beds. There are several species of fungus that home gardeners commonly see growing in mulch, though not all pose a threat.

Orange Fungus

While some fungus is less than noticeable, many gardeners find bright orange patches growing on their mulch.

These patches are often a type of slime mold known as Physarum polycephalum.

Orange Fungus In Mulch

While the color may look alarming, most orange fungi are often perfectly safe, albeit unsightly. 

Yellow Fungus

Yellow fungi growing in mulch are just as common a problem for gardeners as orange fungus, and it’s often caused by a similar issue.

Certain species of slime mold are bright yellow to gold in appearance, which can ruin the look of a perfectly manicured flower bed.

Yellow Fungus In Mulch

Fortunately, most yellow fungi are also harmless to you and your garden. 

Artillery Fungus

Artillery fungus is a species that lives up to its name, shooting out tarry black spores from fruiting bodies like projectiles.

While these spores aren’t dangerous, they can be difficult to remove from house siding, car paint, and other property. 

Artillery Fungus In Mulch

You can recognize artillery fungus thanks to its small, cup-shaped fruiting bodies. Each cup is cream, orange, or brown in color and holds a tiny black spore. If you recognize artillery fungus in your mulch, it’s best to deal with it before fruiting bodies get the chance to release their spores.

Mushrooms In Mulch

Mushrooms growing in mulch are fairly easy to identify. While mushrooms come in a variety of shapes, sizes, and colors, almost all varieties boast a structure with a cap and stem. Mushrooms can pop up overnight, and a single organism can produce an expansive network of fruiting bodies.

While some mushrooms are safe to eat, many are toxic for children and pets. It can be a challenge even for experienced foragers to distinguish between edible and dangerous mushrooms, so it’s best to remove any you see in your garden just to be safe. 

Stinkhorn Fungus

You can sometimes identify a stinkhorn by its smell alone, which many compare to rotting meat. Stinkhorn fungus can vary in color from reddish or orange hues to cream and brown, most often growing out from a small ball into a long, rounded stalk. 

Stinkhorn is a common problem for gardeners, though it appears to favor some mulch beds over others. While stinkhorn fungi thrive in hardwood mulches, they tend to avoid pine bark mulch. Adding pine bark to a mulch bed may help to deter stinkhorn fungus.

 Stinkhorn fungus

Bird’s Nest Fungus

As the name suggests, this type of fungus closely resembles a bird’s nest.

Each fungus consists of a tiny cup, or “nest,” usually brown to gray in color.

Birds Nest Fungus

Inside, a small clump of tiny, egg-like sacs grow, usually tinted white or cream. These “eggs” are reproductive structures, or “peridioles,” and contain spores.

Bird’s nest fungus is non-toxic and typically safe to leave growing in your yard. In fact, many gardeners choose to compost birds’ nest fungal colonies and reintroduce rich nutrients back into their soil.

Slime Mold Or Dog Vomit

Slime molds, also known as dog vomit fungi, are unique in the fungal world because they are multicellular aggregates made up of single-celled fungi. Each cell comes together independently to act as a single unit in order to reproduce and spread spores.

Dog Vomit Fungus

You can easily identify slime molds thanks to their vivid appearance, with most boasting a bright yellow, orange, or even pink color. Colonies can range anywhere from a few inches across to several feet, depending on the species and stage of growth.

Verdict: Getting Rid Of Mulch Fungus

Plenty of gardeners have battled a fungus outbreak in their mulch beds. An infestation can appear seemingly overnight.

Fungi in your mulch bed can be unsightly at best. At worst, fungi growing in your garden may pose a danger to friends, family, and pets. Some species are toxic or even lethal and require immediate removal. 

Fortunately, there are plenty of safe, easy, and cost-effective ways to get rid of fungi in your mulch bed. As long as you can identify the fungus at hand, you can come up with a treatment solution to leave your yard looking pristine and fungus-free.