What is Black Mold on an Onion?

If you go to the store and look at the onions being sold, you’ll notice that a lot of them appear to have a small amount of black mold on the outside of them. This can be concerning, after all, it’s dangerous to eat mold on most foods. However, this is not the case with onions.

The mold that grows on the outside of onions is called Aspergillus niger. It comes from the soil that the onions are grown in and is mostly harmless to humans however, it should be removed before the onion is consumed.

The rest of this article will go over exactly what the black mold is and the best ways to remove it from an onion.

What to Do with Onions with Black Mold

The first reaction that many people have when they find an onion with black mold is to throw the onion away. After all, mold is dangerous and can make people very sick if they eat it, right?

Generally speaking, this is correct. Most food that has grown mold should be thrown away as the mold itself it toxic. Mold is also a sign that the food has not been stored properly which could mean that it also has dangerous bacteria growing on it.

However, in the case of onions, this is not always the case.

The most common mold that you will find on onions is a black mold that grows on the outer layers of the onion’s skin. This mold is called Aspergillus niger. It is a very common mold on onions and frequently grows both when the onions are in the field and once they have been packaged to be sold.

Fortunately, this mold is mostly harmless and is very easy to remove from the surface of an onion. 

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Even though it is rare to get sick from this type of mold, it is still best to remove it. That way you don’t have to worry about the mold affecting the flavor of the onion in any way or worry about the slight chance that you may become sick from eating that type of mold. 

Wash It Off 

The first way to remove this type of black mold from onion is simply by washing it off. To wash it off the onion you’ll want to use a vegetable scrubbing brush and some basic soap. The mold will usually require a bit of scrubbing to come off, but it should still come off relatively easily with soap, warm water, and a bit of elbow grease.

Peeling the Skin

Another super easy way to remove black mold from an onion is by removing the skin. This works best if the mold only affects the outer layers of the onion. 

To use this method you’ll simply want to peel away layers of the onion until you have reached a part of the onion where you can no longer see any evidence of the black mold. Once you have gone that far the onion should be safe to prepare and consume.

To learn about some of the different types of onions and their uses, click here.


If the mold has affected very specific parts of the onion then a super simple way to remove the mold is by cutting it away. This is very easy to do with a sharp knife and a steady hand. Cutting the mold away is also a great option if you want to preserve as much of the onion as possible and don’t want to lose excess onion peeling away layers.

To use this method you’ll simply take a sharp knife and begin to cut away the parts of the onion that are affected by the black mold. The sharper the knife, the easier this will be to do and the less likely you are to cut yourself. Using a sharp knife also helps to reduce the stinging sensation that the onions can cause your eyes.

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Facts to check 

In recent years, there has been some false information circulating saying that the mold growing on onion is mucormycosis. This is a type of fungus that is common in India and can cause serious illness.

To an untrained eye, these molds can look similar which can make consumers concerned that they are going to contract the disease.

Fortunately, mucormycosis is not common in the United States and does not grow on onions. The type of mold that grows on onions is mostly harmless to humans and comes from the soil that the onions are grown in.


Although the appearance of mold on your onions can be scary, it is usually nothing to be concerned about. It is very common for onions to be sold with mild to moderate amounts of black mold growing on their outer layers of skin. This mold comes from the dirt that the onions were grown in and is mostly harmless to humans.

You are able to remove this mold easily by washing it off, peeling away layers of skin, or by cutting away affected areas. After the mold has been removed the onion is perfectly safe to eat and can be prepared and consumed normally.