Does Epsom Salt Kill Fungus Gnats?

Epsom salt contains magnesium sulfate, which is toxic to fungus gnats virtually on contact. So to answer the question, “ does Epsom salt kill fungus gnats” the answer is: absolutely

How to make a solution of Epsom salt to kill fungus gnats?

 If you have a severe infestation of pests going on with multiple plants suffering from these fungus gnats and their offspring:

  1. Prepare four to five gallons of distilled water. You won’t want to add any more nutrients to this solution, and tap water contains too many traces of vitamins and minerals that can harm your plant leaves.
  2. Add two tablespoons of Epsom salt to every gallon of water that you made up
  3. Fill the solution into mister spray bottles

Dowse your affected areas and the soil with this mist spray once or twice a month. If you notice damage to the plant leaves, move back to one tablespoon of Epsom salts rather than two.

Is using Epsom salts the best way to get rid of fungus gnats?

Adult fungus gnats will look for rotting plants or food matter to lay their eggs. So the salt sprays can kill the adult gnats and babies alike.

Alternatives to Epsom salt solution

Another option that kills fungus gnats is adding a drop of dish soap to a pan of a sugary liquid like wine or juice. This will kill many adult fungus gnats to keep them from reproducing. The dish soap poisons the gnats and gets them stuck in the liquid, so they die. 

A combination of white vinegar and water with a dash of dish soap is known to kill both adults and larvae. Just mix all these ingredients into a solution and use it as a spray to eliminate these pesky pests. However, the white vinegar itself does not kill the gnats. But instead, it lures them to the soapy solution to be killed by the dish soap, even in the soil. 

What plants don’t like Epsom salt? 

plants dont like Epsom saltEpsom salt in plant soil is known to burn and kill a fungus gnat on contact. This is also true of most plants’ roots in the soil. Their soil is very sensitive to the acidity of Epsom salts. 

It’s easier to remember the few plants that can take doses of Epsom salt, like tomatoes. Neem oil is a better alternative to Epsom salts when using a fungus gnat killer on plants. If you are unsure if your potted plants can take the treatment meant for killing fungus gnats, that can also inhibit plant growth. 

This treatment will also prevent fungus gnats and can kill common garden bugs, and pests that have been eating ate decaying organic matter in your garden soil. 

Frequently asked questions

Will using Epsom salt damage your plants or affect the soil?

If your potted plants have a magnesium deficiency, it shouldn’t harm the plant if you don’t put too much into the soil. However, a properly fed plant can suffer from nutrient burns on its roots if fed Epsom salt when it doesn’t need it. A safer alternative is using one cup of hydrogen peroxide to four cups of distilled water to make a hydrogen peroxide solution you can safely mist onto your plants and soil to get rid of fungus gnats. The salts will not damage the actual soil itself. 

Can Epsom salt be used as a soil insecticide against any larvae living in the soil of plants in addition to the fungus gnat infestation?

epsom salt kills slugsAbsolutely; it will kill adult fungus gnats and kill the infants living in potted plants. Dry Epsom salt sprinkled around plants and the soil can also kill slugs and snails. 

Why do I have fungus gnats in my home?

Fungus gnats are attracted to decaying organic matter and excess moisture. Did you water your plants after a long dry spell recently? The chances are good that you over-watered your plants’ soil to compensate for having not watered them, and now you have created the perfect environment in which fungus gnats and their larvae can thrive. Now that you have a decaying organic matter on your hands, choose between using Epsom salt to kill fungus gnats or a white vinegar solution. 

Can Epsom salt hurt my skin?

In addition to killing fungus gnats and getting rid of the offspring, Epsom salt spray on your skin is used to heal many types of inflammation, such as bug bites. There’s nothing to be afraid of if you walk through a mist of this solution or even a solution of white vinegar. The salt kills fungus gnats and will get rid of the babies in the soil, but it will also heal your skin

How does Epsom salt kill fungus gnats’ offspring through the soil?

It’s toxic to the fungus gnats’ offspring in the soil to grown fungus gnats. Just use the Epsom salt spray on the babies in the soil as you would for the adults. 


How does Epsom salt kill fungus gnats? By being a toxin! Whether on leaves or soil, the salts are toxic. Before killing fungus gnats with Epsom salt, remove all decaying organic matter from your home. Then you can make up the white vinegar solution and/or the Epsom salt kill spray to kill fungus flies and poison the soil their offspring live in. The best way to kill fungus gnats is at the source: the nest with Epsom salt. 

The nest of the gnat infestation will be around a lot of decaying matter, so it’s important to remove any traces of dead material, rotting food, or moist, dirty items in your home. You can then follow up to kill fungus gnats with various sprays and salts because there will be remaining fungus gnats to kill in the air and within the soil. 

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