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Why Do Basil Leaves Turn Purple? (Explained)

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Last updated on September 27th, 2022 at 12:21 pm

Growing basil plants for food and medicinal purposes is undoubtedly the key reason many people propagate and cultivate this plant.

However, before these purposes are achieved, cultivators certainly experience a certain satisfaction and pleasure from admiring basil’s lush bright green leaves.

They anticipate utilizing these healthy leaves when due, so seeing the basil leaves turning purple becomes disheartening.

Yet, why do basil leaves turn purple? There are numerous reasons why basil leaves turn purple. An excellent explanation for this phenomenon is the deficiency of phosphorus in the soil where basil is grown.

This explanation is especially true when the basil plant leaves start with a bright green pigment.

Does Basil Turn Purple?

Even though basil is widely known and identified by its characteristic light green color, certain conditions could cause it to trade that color for another, such as white, red, brown, black, and even purple!

So, yes! Basil leaves can turn purple. Remember, though, that this is not a natural order for basil. Instead, they are meant to be harvested green and fresh.

An endearing feature of the basil plant is the ease of propagation and cultivation. This occurrence is mainly due to its requirement for trace amounts of soil nutrients to thrive.

Also, being a fragile plant not resilient like weeds, it is expected to immediately show symptoms of a deficiency in any of the required nutrients.

This sign is usually done by the change in condition and coloration of the leaves.

It is important to note that the purple coloration of green basil leaves is not necessarily an indicator of the immediate death of the basil plant.

You would have noticed that even though the color of the leaves has changed, it is not accompanied by a corresponding sharp change in the overall health of the basil plant.

The stem remains firm, and the leaves stay broad and smooth.

What if you propagate basil by seed (i.e., planting of basil seeds) and you anticipate a bright green plant only to see upon germination a purple coloration right from the onset?

Well, this could probably mean that you have sown purple basil! So, there is a species of basil plant that occurs naturally with a purple coloration, and it is just as healthy and flavored as the green basil.

Why are some of my basil leaves purple?

When a basil plant starts all green with fresh green leaves, it is safe to conclude that it is green basil, not a purple basil plant.

However, as it grows, some leaves may begin to turn purple, as has been noticed in some unusual cases. What is the reason behind such a change?

The reason for the purple coloration of some leaves of green basil is a phosphorous deficiency.

Just as Nitrogen is essential in a plant to keep the leaves smooth, fresh, and fleshy, so is Phosphorus necessary in retaining the green pigment of the leaves.

Therefore, when basil plants lack phosphorus, a purple coloration in the leaves usually occurs in proportion to the level of deficiency of that nutrient.

This lack of phosphorous in the basil plant is majorly a lack of phosphorous in the soil where it is planted.

Since we cannot discern the nutrient content of soil by simply looking at the soil, we can only judge the nutrient content of soil by the welfare of the plant growing on it.

Thus, when basil leaves turn purple, it usually indicates that the ground it grows lacks phosphorous.

Sometimes, the soil may be rich in phosphorous but still produce purple basil leaves. In this case, it may be that the soil is cold.

Basil is a tropical, heat-loving plant, so the plant is also affected when grown on cold soil.

Here, the cold prevents the roots from taking phosphorous present in the soil to the plant body, where it is synthesized, causing the leaves to turn purple.

Basil also thrives in soil with a PH range of 6.0-7.0. Therefore, if the soil is more acidic than this, the basil plants’ roots cannot absorb the available phosphorus from the ground up.

Hence, making the basil plant phosphorous deficient is evident in the purple coloration of its leaves.

How do you revive purple basil?

As we have established, the purple coloration of basil leaves is not necessarily a death sentence to the basil plant.

On the contrary, it can even be considered a reversible change if one knows how to go about it. So, how can purple basil be revived?

If you are looking to restore and revive purple basil, consider doing the following;
1. Remove all purple leaves on the plant, as this will enable the plant to focus its energy and available nutrient on valuable leaves.
2. Use organic manure like cattle and poultry droppings to boost the nutrient content of the soil on which basil is grown.
3. Prepare and apply compost manure. Compost can be prepared by simply collecting organic waste like dead leaves and allowing them to decompose in a container or shallow pit until they become refined, dark, and rich soil.
4. Use fertilizers with an exceptionally high composition of phosphorous to supplement the soil nutrients.
5. Provide shade temporarily for the basil plant. Purple-colored basil is stressed basil. Temporarily shading the plant will enable the plant to relieve stress.
6. Timely harvesting will ensure the proper utilization of available nutrients.
7. Mulching also helps to retain soil moisture and thus encourages the recovery of the basil plant.
8. Test soil for acidity and alkalinity and improve appropriately.
9. Keep soil moist but warm by avoiding overwatering.


Basil leaves are the main product of basil plants, and keeping these leaves healthy remains a priority. It is, therefore, unfortunate to see basil leaves turning red or purple.

Although this is caused by nutrient deficiency, purple basil can be revived to the lush green leaves we cherish.

Applying the lessons from this article will enable us to rejuvenate and prevent our basil from gaining purple pigmentation.

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