How to Get Rid of Fungus in Mulch

Are you done with seeing fungus in your mulch every other day? I was up to my neck because of this very common problem a few years back so that’s why I am here with a complete guide to let you help with getting rid of the fungus in a matter of days.

Mulch works as an antibiotic for plants. It kills the reasons(fluctuating temperature and invasive weed) that are ruining your plants.

What causes fungus?

The decomposition process develops fungi. So, mulch and fungus both work in a symbiotic way. They live and keep on growing by consuming the bacteria present in the mulch. This reason makes it hard to put a full stop to this problem. The most accurate answer to this question would be that the decomposition process causes fungus in mulch, and the bacteria acts as a guiding star so it keeps on growing.

What invades mulch more often?

There can be many culprits but the proven ones are slime mold, stinkhorns, and artillery fungus.

If it has just started happening, the solution is simple

If you have noticed a tiny bit of mulch fungus, know that you are safe. All you have to do is to take the affected portion out of the mixture to prevent it from growing.

There are many other methods as well but they need to be applied only when the problem starts going out of one’s hands.

But taking the “affected part of the mulch out” method fails in some cases

The method works for some but for some, it makes the problem even worse. The fear of fungus growing somewhere down is still going to haunt you because the reasons that cause fungus to happen are still there. To bring the effectiveness in this method you have to keep noticing the mulch every day. So as soon as the new fungus starts making its way, you can remove it right away. It will slow down its growth as you will not be allowing its spores to spread this way.

get rid of fungus in mulch

How to get rid of fungus in mulch

There is more than one way to treat mulch fungus. Here are some of the ways discussed to help you resolve the problem.

Dig & Dispose

One of the simplest ways to treat fungus is to dig out the infected portion and dispose it. There are some risks attached to this method

Caution: Wear a mask when digging mold as breathing in the mold spores may be dangerous for people with asthma or allergies. 

In an attempt to move the infected mature mulch, spores spread may happen.

Vinegar Spray

Vinegar spray is one of the simplest methods of treating mold and fungus. Spraying the mold with vinegar kills the fungus growth. The acidity of the vinegar works like a charm in getting rid of the fungus.

Caution:  Be cautious when spraying vinegar. Do not spray it on or near the plants as along with fungus it will kill the plant as well.

Make a vinegar solution by adding water to make it less acidic.

Acidic/Basic Soil

Fungus growth can be prevented by making the soil or mulch more acidic or basic. A pH too high or too low will kill the mulch fungus. To raise soil pH, add lime, whereas, to lower the pH of the soil, add sulfur.

Caution: Raising or lowering soil pH is harmful to the plants nearby. The plant may die, or, their growth shunned. Plants like blueberries or azaleas, if the soil is made acidic for preventing mold. Grow plants that support acidic soil.


Fungicides are a go-to option for those looking for a quicker and result-oriented solution. Many safer organic fungicides deliver results with less environmental impact.

Caution: Follow the instructions manual.

Use Hose/Watering Can

Overwaterered plant beds create a perfect scene for fungus growth during the wet spring months. Watering the plants with sprinklers will give rise to fungus.

Caution: Use a hose or watering can water each plant individually. Do not spill water anywhere, except the plant roots. 

fungus in mulch

Baking Soda and Cornmeal

Baking soda and cornmeal are two organic alternatives to fungicides. Add one cup of cornmeal in 1 gallon of water and spray it over mulch or sprinkle cornmeal over the mulch and water the infected part.

Baking soda can be used in the same way as cornmeal, the only difference is adding two tablespoons of baking soda in a gallon of water.

Bleach Spray

Spraying the mold with bleach is also one of the effective ways of treating mold. If done correctly, the diluted bleach solution gets the job done without causing any harm to the plants.

Caution: A diluted mixture of one part bleach and 9 part water is only used so as to not harm plants.

High-Temperature Kill

The ideal temperature to kill mulch fungus is 104 degrees F or 40 degrees C. There is no need for fancy heating devices to achieve this. Water the mulch thoroughly and keep it in the sunlight for a couple of weeks. The decomposition process will raise the temperature high enough to kill the fungal colonies.

Caution: Do not water the whole mulch thoroughly, only the infected part.

Besides annoyance, what are the dangers of mulch fungus

Yes, not just the annoyance, it brings a lot with itself if not treated on time. It may or may not be poisoning but it can decay and break down the mulch in a matter of days. So, hurry up before it’s too late, do not let it ruin your mulch.

And what makes “getting rid of it asap” a need of the hour

It should be treated as soon as possible as it keeps on growing. Most gardeners recommend preventing it from happening in the first place but if it has already happened you need to move fast to nip the evil in the bud.

Final Word

Mulch fungus is a nightmare for the garden and needs a constant check. It is better to nip the evil in the bud than let it spread over. Hardwood mulch is more prone to fungal attacks. Softwood mulches, made from pine are resistant to fungal spread than other mulches. It is easier to prevent mold growth on organic mulches.

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