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Why Do Basil Leaves Turn Red? (Explained)

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Last updated on September 27th, 2022 at 12:16 pm

Basil is a pretty wonderful herb to grow in your garden. This plant’s leaves serve various purposes that make it indispensable in every nursery where you find it.

This plant is very beneficial, from helping to alleviate colds to even curing worm infections. So, we tend to want to grow as much as we can.

However, it can be frustrating to see your Basil plant not grow well. And there are many anomalies that you may notice in the course of its life. One of them is the leaves turning red.

Why do Basil’s leaves turn red? Basil leaves turn red when the plant produces excess anthocyanin under certain conditions. The anthocyanin circulates the plant, and when it reaches the leaves, it makes them turn red or purple.

What Does It Mean When Basil Leaves Go Red?

When Basil leaves turn red, it is usually a result of increased anthocyanin levels. If your basil leaves turn black after washing, I recommend you, please read this article.

Anthocyanin is a water-soluble chemical found in plants like Basil. It is a pigment, just like chlorophyll.

However, it occurs naturally in different colors, and just like chlorophyll, it influences the color of certain parts of plants. 

Anthocyanin could be black, purple, red, or blue, as seen in some berries and flowers. This is because anthocyanin belongs to a group of molecules called flavonoids.

Flavonoids were once called vitamin P because of their many health benefits. They are present in plants with deep colors.

You may wonder whether your plant that’s naturally supposed to be green turning red is okay.

If you want to find out, please keep reading as I’ll explain how anthocyanins affect your Basil.

Is It Good For Your Basil Leaves to Turn Red Because of Anthocyanins?

Anthocyanins are very beneficial to your plant. They help protect your plant against the adverse effects of changes in environmental factors.

One of the most critical environmental factors affecting Basil is sunlight or high-intensity light.

When your plant receives more light than it needs, its chloroplasts produce a type of oxygen that’s bad.

This reactive oxygen species can alter your plant’s DNA and cause many more problems. Anthocyanins in your plant help reduce the light your plant absorbs in such cases.

Furthermore, they warn you of the environmental stress your Basil is facing.

So, it’s not normal for your Basil plant to turn red, but it is the only way it can keep itself from being affected by the adverse environmental conditions it faces.

What Causes Your Plant to Produce More Anthocyanin than Usual?

Several factors could cause an increase in anthocyanin levels in your plant. They include:

1. Exposure to Excessive Light

The amount of light your Basil plant receives significantly affects its anthocyanin level. Light is an essential factor for plants, especially in photosynthesis.

In addition, light helps your Basil plant to generate ATP that it needs from its carbon dioxide synthesis. This is a critical part of your plant’s daily activity.

However, research has proven that intense light encourages anthocyanin production in plants. This increase in its production causes your plant to turn red. 

If you suddenly transferred your Basil to a green room with a lot of light entering it, it is most likely the reason it’s turning red. 

Also, if there’s an increase in the amount of sunlight your plant receives over a while, you’ll notice that its leaves will gradually turn red.

2. Increase In Magnesium Levels

Magnesium is an inorganic element that helps in plant growth. It is very beneficial to your Basil plant as it allows the plant to absorb carbon dioxide in vital areas.

It also helps in photosynthesis and phot assimilates transportation in your plant. Nevertheless, excess amounts in your Basil plant could cause it to produce more anthocyanin.

This, in turn, causes your plant’s leaves to turn red. If there is an increase in the magnesium content of the soil where you planted your Basil, it could likely cause its leaves to discolor.

This occasion is rare, however, since magnesium is a non-renewable mineral.

So if you added magnesium yourself, probably from fertilizers, it is most likely a factor causing your plant to have more anthocyanin than usual.

3. Exposure to High Temperature

Temperature is one of the most critical factors that affect your Basil’s growth. In average temperatures, your plant will thrive well.

The daytime temperature is between 70-80 degrees. Fahrenheit benefits your plant.

However, there are times when daytime temperatures can fluctuate, increasing more often than not.

During these periods, anthocyanin levels in your plant will creep up to incredible levels. The chemical will be distributed in the leaves, turning red.

Are Anthocyanins Responsible for the Yellowing of Basil Leaves?

No, anthocyanins are not directly responsible for the yellowing of Basil leaves. The yellowing of leaves is called chlorosis.

There are a couple of reasons why your Basil could turn yellow. First, it could be because of.
1. Inadequate water levels.
2. Damaged roots.
3. Nutrient deficiencies.
4. Frigid temperature.
5. Excessive heat.
6. Too much sunlight.

How to Restore Your Plant to Its Normal Color?

I have established that Basil turns red because of anthocyanins produced in response to changes in environmental conditions around it.

You can restore your Basil’s lush green color by tackling these changes. Some steps you can take include

1. Providing shade for your plant

If you grow your Basil in an outdoor nursery, it would be best to construct a shade to prevent excessive sunlight from harming it. It would also regulate the heat that reaches your plant.

2. Reducing the amount of light that enters your greenroom

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If you keep your plant indoors using artificial UV lights to grow it, you should reduce the intensity of the light it receives.

This would curb any adverse effects that lead to anthocyanin production.

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3. Always apply organic fertilizers in the right amount

It would be best to treat the soil you planted your Basil on with an adequate amount of fertilizers rather than too much.

4. Provide enough water for your plant

Dehydration during the period when your plant is countering adverse effects of environmental factors could cause chlorosis after it turns red.

Therefore, always ensure that your plant is well watered.


Basil plants discolor for several reasons. Turning red is primarily due to increased anthocyanin content in the plant.

This is a defense mechanism against adverse conditions and stresses your plant undergoes.

While anthocyanins are not bad, you should always ensure you take the necessary measures to restore the natural color of your Basil’s leaves.

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