Why are your basil leaves turning black? (Cause and solutions)

Basil are types of the leaf which we commonly use for cooking and medicines, but how does it feel when your beautiful, fresh leaves turn black???

Primarily, today I will chew over the fat with you about the basil leaves. To the best of my knowledge, many of you might know the benefits and uses of these leaves, but some people are anxious to understand why basil leaves turning black or brown?

There is no specific reason why basil leaves turn black or brown because almost all leaves have the same issues and common causes. But, in general, if you want to know why the reason is due to oxidation.

In this garden gild guides we’ll discuss the following:

  • Why basil leaves turning black or brown?
  • Are basil leaves terrible when they turn black?
  • How do you keep basil from turning black?
  • Why are basil leaves losing color?
  • How long will basil keep in olive oil?
  • How do you get rid of black mold on basil leaves?
  • FAQs
Why are your basil leaves turning black thumbnails

Why basil leaves turning black or brown?

Just think about an apple or guava. After you cut or eat some of the apples, you will see some black marks on the areas of the apple or guava on which you bite. This is the same case with basil. 

There can be other reasons for which basil leaves turn black or brown. The reasons are:

  • Deficiencies of nutrition
  • Fungi and bacterial diseases
  • Pests
  • Exposure to excessive heat and cold

Let’s know about this in detail.

1. Deficiencies of nutrition:

If the human body does not maintain a balanced diet, it will suffer from various diseases due to improper nutrition. And it is the same case for basil or any other kind of leaves.

If basil leaves get less or excess amount of nitrogen or any different types of chemical compounds such as potassium, magnesium, iron, etc., from the soil, leaves will turn yellow or pale from the green leaves.

Eventually, it will change into brown or black. This states that they do not have proper nutrients.

2. Fungi or bacterial diseases:

Fungal and bacterial infections are typical for the basil leaves. In basil leaves, some bacteria disease, Pseudomonas Cichorri, can be made when the soil is unavailable to deliver proper nitrogen amounts.

If these leaves are kept in a wet area, that spreads due to the rain and watering time. This can cause bacterial disease that leads the basil to have some black or dark spots and leaves begin to dry out, and many holes are created on the leaf.

With the help of host pathogens, Peronospora belbahrii, related to fungal diseases, yellow spots occur on the leaves due to downy mildew symptoms. If the yellow spots increase, it will slowly create brown/ blacky, wet, slimy blotches on the leaves.

 3. Pests:

Some pests, such as aphids, thrips, spiders, etc., love to live on the basil leaves. If these types of problems once started to get freedom and you kept it untreated, you will see black spots on your basil leaves after some days.

This is because they will create some perforation in the leaves, and due to the invasion of these insects, your leaves will become weak and eventually spread on the nearby whole leaves.

4. Exposure to excessive heat and cold:

Although different herbs can live in cold and hot temperatures, basil leaves can not tolerate excess heat and cold temperatures.

They are generally herbs which we use for cooking. If kept under high or low temperatures,  it creates black, irregular, small round shapes on the basil leaves. They will die if not properly maintained because they are sensitive to exposure to excessive heat or cold.

How do you keep basil from turning black?

It may not work 100% efficiently, but I suggest some general ideas to keep basil turning black.

Some of the primary methods are:

  • Do not use Too much fertilizer
  • Do not Overwater basil 
  • Remove the basil leaves which are infected or eaten by the insects such as aphids, caterpillars, spiders, etc 
  • Use sticky traps 

1. Do not use too much fertilizer: 

If you use too much fertilizer on the basil leaves, it can overdose salts on the soil. You know, fertilizer contains various chemicals such as Nitrogen, Potassium, Magnesium, etc., that can lead the basil leaves from turning black. So do not use too much fertilizer. 

2. Do not Overwater basil:

Overwatering basil or other leaves is not a good idea because the leaves’ cells will become weak. Before that, you can see some black marks on the leaves, which tell us basil leaves will not live longer. If you do not Overwater, it may reduce the black or brown spots.

3. Remove the infected or eaten leaves from the insects:

Do not keep the infected leaves with the fresh basil leaves because if the insects start to stay in the leaves, they will produce larvae or eggs very quickly. So there will be a chance for them to spread microorganisms and remove the eggs visible to your eyes if possible. Instead, you can clean the basil leaves by putting this into edible soapy water.

4. Use sticky tapes:

After cleaning the infected leaves, you can check the leftover tiny insects using sticky tapes. Most of the leftover insects will be attached to this tape. The lesser the number of insects or larvae, the lesser the chance for the basil to turn black or brown.

Are basil leaves terrible when they turn black?

Are basil leaves terrible when they turn black?

Yes, basil leaves are terrible when they turn black.  Becoming black can be considered as a sign of a rotten smell. It looks awful when green basil turns black, smelly, watery, and slippery like a snail body and loses its natural oil as the basil leaves become older.

Why are basil leaves losing color?

There are three reasons why the basil leaves are losing or changing color. Some of the reasons are:

  • The time when basil leaves are not getting enough nutrients
  • Too much or too little water
  • Too much scorching  heat or too little heat

How long will basil keep in olive oil?

If you keep basil leaves in olive oil, it will last up to 48 hours or more if the condition of the basil leaves is entirely perfect. Besides, with olive oil, you can put these leaves into the butter or salt, etc.

How do you get rid of black mold on basil leaves?

There are some easy solutions to get rid of black mold on basil leaves. They are:

  • Firstly, you have to remove all the basil leaves that have become black and any hole. Because if you do not remove or throw it in the waste bin, there can be a probability of spreading the microorganisms. For this, other fresh basil leaves can be damaged or filled with black mold on the basil leaves.
  • After buying basil leaves from the shop, try to eat the leaves in one day.
  • It will be good if you do not use the basil leaves for compost because it can not kill the microorganisms if they do not get enough heat.

1. How do you know if basil’s root is rotten?

You know, basil’s root is generally soft and wilted. So if the heart becomes weak and fully bend, they can not raise their heads off the leaves.

If the soil is moist, it can grow fungi with basil roots that can cause damage to the basil leaves. The root is the central part of the basil to develop. Avoid watering too much.

2. How do I know your basil is overwatered?

It is straightforward to understand if your basil is overwatered because the colorization of the basil will change. It will change from green to pale yellow color, which means the growth of the basil is falling down day by day.

After some days, you will notice basil leaves crying looking down. If the water is too excessive, it will not grow, and due to the lack of care, it may die.

3. Is black basil okay to eat?

NO WAY! Why should you even taste the smelly rotten black basil? 

Black or discoloration is due to bacterial or fungal infection. These types of microorganisms containing leaves can be caused by the fungus Pseudonymous Chichorri.

I would highly recommend not to taste a bit, especially if the basil leaves have become slippery like a snail’s body and slimy. It can cause various types of diseases such as rashes in your throat and diarrhea etc.

Relevant post:


Basil is a leaf that protects against infection unless you eat the rotten one!!! And do not try rotten basil or other kinds of food, and you will feel nauseating if you want to eat it.

So, eat fresh and be healthy. If you want to know more about any topics, be our guest and share with your friends.

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