3 Causes of Brown Spots On Mint Plant [Troubleshooting Guide]

Will you eat if you see the mints on your salad have brown spots? probably not! 

You wouldn’t wanna serve that to your guest also. And if you are growing mints to sell, then this brown spot surely is a big concern for you.

Luckily you can fix this problem if you take the right steps at the right time. But before that, you need to know what are the reasons behind it.

There are 3 reasons for brown spots on mint leaves, i.e. Fungal Disease, Viral Disease, and Pests.

In this article, I have tried to provide all the necessary information to fix the brown spot of mints with their easiest solutions. So that you can easily cure your precious mint leaves.

How to Fix Brown Spots On Mint Leaves- Solution

1. Fungal Disease of Mints

Mint Rust is caused by a fungus. It mainly affects the mint family, especially spearmints and peppermints. It starts with small brown spots on the mint leaves. When the rust goes on advanced stage the whole leaf turns brown and falls off from the plant

Downy mildew starts with yellow spots on the mint leaves. The spots gradually become dark and brown. Also, you will see a grey fuzzy growth on the lower side of the leaf.

Fungal leaf spots also cause dark brown spots on your mint and basil plants. Their severe infestation kills the plants. All these fungal diseases are favored by damp and humid conditions.

Control Measure

Start by removing all the leaves with brown spots. Then you need to use an all-purpose fungicide that is best for herbs (our pick: Bonide Copper Fungicide)

Avoid overhead irrigation. Because, if the leaves stay wet, this rust will keep attacking. Plant mints with enough space between them. 

Don’t let the brown leaves mix with potting soil. Burn them or throw them in the garbage. 

You can try these DIY homemade fungicide recipes on your mint plants. 

#Recipe 1:- Baking Soda Spray Recipe


  • 2 tablespoons of baking soda
  • 4 tablespoons of vegetable oil
  • 2 gallons of water
  • 3 teaspoon of liquid dish soap


  • Mix everything together and shake thoroughly
  • Spray this solution on both sides of mint leaves with brown spots.

#Recipe 2:- Vinegar Spray Recipe


  • 1 tablespoon of apple cider vinegar 
  • 2 liters of water
  • Few drops of liquid dishwashing soap


  • Mix the ingredients and shake.
  • Spray on both sides of the infected leaves until the fungal problem is solved.

Note: Try the homemade recipes on a small leaf first. Wait to see the reaction. If the leaf burns then add some more water and dilute the solution. Then try again. If still it doesn’t work then try the other recipe.

Preventive Measure

To free up some space, prune some old leaves. In the case of indoor potted mints, keep them away from walls or corners for better air circulation. Disinfect the potting mixture yearly.

Water your mints from the bottom instead of on the leaves. Water them in the morning. This way extra water can evaporate from the mint leaves.

2.Bacterial Disease

Bacterial attacks sometimes cause brown or black spots on the mint leaves and other herbs like basil and oregano. The brown spots look angular and water soaked. The bacterial infection can even affect the stems. 

So, when you see spots on the stems too then you know what is making brown spots on your mints.

Control Measure

Pick out the water-soaked brown-spotted leaves and cut off the parts of the infected stem. Then apply a good bactericide on your mints (our pick: Monterey Fungicide & Bactericide)

Follow the same preventive measures mentioned in the Fungal disease section. 

3.Pests of Mints 

Aphids are a serious enemy of mints. They suck the nutrients from the leaves and produce a sticky brown substance. So, the leaves get brown spots wherever they feed. 

Herbs like mints, basil, and oregano are very susceptible to slugs. Slugs feed on the leaves and make brown spots with a slimy trail.

Control Measure

For a small infestation of mint aphids, give a strong spray of water. But they attack a large scale. So, you need to use the best insecticide that does not contain harmful chemicals (our pick: Monterey Garden Insect Spray)

Slugs cannot be killed by regular insecticides. You need to apply Slug and Snail Killer (our pick: Ortho Bug-Geta Snail and Slug Killer)

Toads eat slugs so you can encourage toads in your garden for natural slug control.

Try these homemade insecticide recipes given below for organic control of aphids:

#Recipe 1:- Neem oil Recipe


  • 3 teaspoon of pure neem oil
  • 1 teaspoon of liquid dish soap
  •  3 liter of water


  • Add water and neem oil into a mixing bowl
  • Stir slowly. Then add the liquid dish soap
  • Pour it into the spray bottle
  • Spray this mixture on the affected leaves every 2-3 days. 
  • It is very effective against aphids and safe for application.
  • You can spray this solution regularly to prevent aphids.

#Recipe 2:- Orange Spray Recipe


  • 2 orange peels
  • 1 liter of water


  • Boil the water in a pot and then remove it from heat.
  • Add the orange peels to the hot water.
  • Cover the pot with a lid and let it stay until the water cools down.
  • Remove the peels and pour this into the spray bottle
  • Spray them on your infected mint leaves twice a week.

#Recipe 3:- Garlic and Hot Pepper Spray Recipe


  • 3 garlic cloves
  • 5 large chili peppers
  • 2 liter of water


  • Put the garlic cloves and chili peppers in an electric blender to make a paste.
  • Strain this garlic-chili mixture very well with a fine cheesecloth. 
  • Now mix them with water 
  • Pour the solution into the spray bottle.
  • Use this solution twice a week as long as you see aphids on your mint plants
  • Do not let the solution come in contact with your skin or eyes. Wear disposable gloves while spraying

Frequently Asked Questions (FAQs)

Can I Eat Mint Leaves With Brown Spots?

If the brown spots are made by insects then you can eat them after treating them properly. But if it’s due to fungal or bacterial disease then you should not eat them. These leaves will not taste or smell good.

Can Brown Spot On Mint Leaves Come Back?

If the brown spots are treated properly and the plant is taken care of then the spots will not come back.

Is Mint Rust Fungus Edible?

No! The leaves with mint rust or any other kind of fungus should not be eaten. It can create health hazards like diarrhea and other problems.


Fix the Fungal and bacterial issues and prevent your mints from pests. The brown spots on the leaves will not be a problem anymore.  

In this article, I tried to explain how to treat the brown spots on mint leaves. I hope you found this writing helpful while solving the problem. 

If you have any further questions ask away in the comment section below and share your experience with us about the brown spots on your herbs.

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