5 Causes of Mint Leaves Turn Brown[Complete Solution]

Mint is an outstanding aromatic, perennial herb under the genus Mentha of the family Lamiaceae. It is a very popular plant among gardeners for its aroma and other health benefits.

But like all other plants, mint can also get affected by various types of problems and diseases. Turning the leaves into brown is one of them.

If the disease has already spread vastly and you don’t take any action to solve then it may destroy all the mint plants of your garden. Luckily, If the disease is at the beginning stage then you have got your time to fix it.

In this article, I have described the causes and solutions of the mint leaves turn brown. I hope you will find it effective.

So, without losing your time let’s get started-

What is Exactly Happening with your Mint Plant?

Probably you notice that your mint leaves are turning brown, having spots here and there. Or part of the leaves has already been turned into brown. After a few days, the leaves die. Eventually, other leaves get affected and then the whole plant.

Why are the Leaves on the Mint Plant Turning Brown?

Sometimes brown spots appear for simply lack of light as well as photosynthesis, lack of fertilizer, or just in case of some chemical changes of the plants. In this case, the brown spot will be very tiny and light and you don’t have to take any step rather wait for a few days and it will vanish automatically.

But if the brown spots have sprayed vastly then it can be a result of fungal rust, bacterial blight, or insect/pest attack. Read throughout to know the causes and solutions in detail.

1.Fungal Rust of Mint

Fungal rust is one of the most common problems for basil and mint to gardeners. Even, different types of fungal organisms can develop diseases to your indoor mint plants.

If the brown spots are on the underpart with a complementary yellow splotch on top of leaves then it is suspected as rust, a fungal disease. It is normally affected by Puccinia menthae.

The solution of Fungal Rust

First, you need to destroy infected mint leaves so that it cannot affect other leaves. After destroying, prevent further mint rust by irrigating the plant at soil level as well as providing adequate airflow around it. Then apply a fungicide to kill the fungus.

Here is the homemade solution for fungal disease-

#Neem Oil 

Neem oil is a very effective solution for fungal rust as well as insects or mites. The benefit of it is It will not affect your health, your children, your livestock, or pets. It contains azadirachtin that kills fungus without doing any damage to the plants.

Good news; you can prepare it at home easily. Here are the simple steps you can follow: 

  1. Mix 2 tablespoons (1 ounce) of the Neem oil with one gallon of water thoroughly.
  2. Then spray all over the plant surfaces (including the bottom side of leaves) until completely wet.

Don’t have any extra time in hand? Don’t worry here is ready to use Neem oil for you- Natria 706240A Organic Neem Oil Concentrate

#Baking Soda

If you want a gentler solution then try utilizing baking soda. Baking soda (sodium bicarbonate) is a very effective antifungal agent that can even destroy some established fungus. Additionally, it is entirely non-toxic for mammals, and affordable.

You can prepare the baking soda spray easily at home. Here is the procedure-

  1. Mix 1 teaspoon of baking soda with one quart of water. 
  2. Add a few drops of liquid soap to spread the solution as well as stick to the leaves.
  3. Pour the solution into the sprayer and spray it on the foliage.

#Ready to Use Fungicide

If you want to get a ready and quick solution for the fungal rust. Here is the quick-acting fungicide that you can spray on your mints to treat and prevent fungal disease including rust, black spots, and powdery mildew-

2.Bacterial Blight of Mint

Bacterial blight is a bacterial infection which also results in damping off, a seedling sick condition. 

Although it normally infects the mint’s primary stem and the leaves too that causes brown spotting and finally kills the leaves. The infection may enter your other house plants or cuttings with newly brought from outside.

The solution of Bacterial Blight

To save your mint plant from bacterial blight, you need to prune affected twigs 8 to 12 inches below the case of observable symptoms and dispose of them by either burning or burying.  Always try to prune your mint in dry weather, and after each prune, disinfect the pruning shears with bleach solution. Soak them for a minimum of 30 seconds in a-

10% bleach mixture, or Alcohol (spray disinfectants which include at least 70% alcohol).

#Copper-Mancozeb Fungicide

You can also use a mixture of copper and mancozeb-containing fungicides to control bacterial blight by applying every 7 to 10 days interruptions as leaves originate. Two or three application is enough to get rid of it.

Here is the recommended ready to use Copper-mancozeb Fungicide-

3. Insect/ Pest Attack

A plethora of two-spotted spider mites (Tetranychus urticae) decreases a mint plant’s proficiency to run photosynthesis. The mite’s nourishing results in brown spots on the foliage and leaves. Spider mites grow when the air and soil are dry and also when the air temperature is higher than normal. 

They are tiny microscopic creatures, so you need to use a magnifying glass to search them. Also, four-lined plant bugs (Poecilocapsus lineatus) live on mint leaves, resulting in brown, dead scars behind.

The solution of Insects and Pets

Rinse the mint plant into cool water to eliminate the mites, and spot the pot in a cooler location. 

#Homemade Oil Insecticide Spray

You can prepare an oil spray for your plants from vegetable oil and mild soap (Our pick: product name). It can control and kill the most destructive insects like mites, aphids, thrips, etc.


  1. Make a solution using 1 cup of vegetable oil and 1 tablespoon of soap. Then shake and mix them completely.
  2. Add 2 teaspoons of the oil spray and 1 quart of water.
  3. Shake properly and spray on the affected plant surface.

#Homemade Insecticidal Spray

You can use the insecticide soap spray, which is also very powerful for controlling mites, beetles, aphids, whiteflies, and many other insects.

To prepare a basic soap spray insecticide, just follow these steps:

  1. Measure 1 or 1/2 teaspoons of mild liquid soap and mix it with 1 quart of water.
  2. Now spray the solution on the affected surfaces of the plants directly.

#Ready to Use Insecticide

There are lots of ready to apply insecticides available today. All are very effective to get rid of different types of insects. Here is the recommended insecticide that can help you to get the insects free mints-

4.Cultural Causes

Mint plant does not allow salt and shows its irritation by turning leaves brown as well as crispy. 

The solution of Cultural Problems

Spray liquid 10-10-10 fertilizer by following the label directions of the fertilizer. The rule of thumb is to use 7 drops in 1 quart of water and then water the mint with the solution every 4 weeks. 

If you notice white salt crystals on soil, you should leach the soil with water by flushing four to five times, letting it drain entirely between flushes.

5.Viral Diseases

This 20 varieties of the virus under the Tospovirus genus can be affected the mints. Although it is rare indoors, it is logical to enter the virus with new plants. Symptoms of this include dead growing tops and dead brown spots on the leaves.

The solution of Viral Diseases

Unfortunately, there is no cure for the infection and the best procedure of action is to eliminate the plant and dispose of it to stop spreading on other plants.

Caution: Don’t use too much pesticides or solutions for the first time. It can burn your plant leaves. Before spray, the whole plants, test on a few leaves, and wait. If you notice any burn signs, then apply thoroughly.

Some Mint Care Tips

  1. If it is identified particularly Diplocarpon rosae or another fungus then you should use chemical fungicides or Neem oil or water and milk solution. But if the fungus spread vastly, the fungicides won’t be a decent idea.
  2. Try to isolate and destroy those leaves that are already affected. Thus you can protect other parts of the mint plant. 
  3. Fungi rapidly grow in moisture situations. Try to water adequately.
  4. Sometimes you can buy plants that are already affected. So be careful when buying them.
  5. Get a magnifying glass and inspect your mint plant occasionally.
  6. Get rid of debris like dead leaves or egg shells that can cause fungus issues. 
  7. Try to plant a new mint plant in a pot that contains holes. Because holes are important for water drainage and mint plants require it in order to grow well.


I have tried to provide all the necessary information and solutions covering the whole topic of mint plant leaves turning brown. I hope that your mint plant will be healthy again gradually. Take proper care of it and if possible, then consult with a plant doctor with some disease samples.

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