Why is my basil turning yellow with brown spots

Basil is an indispensable herb in many different cuisines. It helps increase the flavor of dishes and increase the ability to purify the body effectively. As a result, this herb is grown in many parts of the world, even in non-tropical countries.

From that, many people wonder “Why is my basil turning yellow with brown spots?” This article will show the main causes and how to make this tree grow well. Keep reading for more useful tips!

Why Is My Basil Turning Yellow With Brown Spots?


This herb only requires soil with light moisture rather than being soggy. Therefore, when the leaves turn yellow, it is the first sign that its roots are waterlogged. Then, it cannot absorb the necessary nutrients.

Fungal Disease

Several fungal diseases can cause basil leaves to turn yellow, but the most common is Downy Mildew. It is moisture-loving and thrives in humid, low-wind environments. The obvious sign is the discolored with the underside gray or translucent.

Once the leaves are infected, you can only eradicate the root by cutting off the infected parts or abandoning a plant altogether. This method will prevent it from spreading to other plants.

Growing Conditions

Basil is native to tropical countries where the climate is warm and receives a lot of sunlight. Thus, when the temperature turns cold or there is a lack of sunlight, it can turn yellow.

The temperature range day and night is usually 21 degrees Celsius and 10 degrees Celsius, which is suitable for plants to grow. However, you can also use artificial light to balance the temperature, about 10 to 12 hours a day.

Lack Of Nutrients

This herb’s ultimate cause of color variation is a lack of nutrition. It can grow well in poor soil but needs fertilizing during the breeding season. You need to use slow-release fertilizer and fertilize about every six months.

A potassium deficiency usually causes yellow leaves. You can add this substance to the plant through fertilizers containing potassium-based salts. In addition, at the end of each crop, you should also take care and add nutrients to the soil before setting up a new one.

How To Treat

Water And Sun

Basil usually requires about 1.5 inches of water per week to grow well. At this time, you must pay attention to two points so that the leaves do not burn or become waterlogged:

  • Water carefully around the root
  • Limit wetting the leaves

To avoid the same problems, you should also use a pot instead of a hose, as it can splash water on the herb. Moreover, it also needs at least 6 hours of sunlight a day and a warm temperature to develop better.


Before planting, you should spend about two weeks improving the soil. For every 100 square feet of soil, you can use about 3 quarts of 5-10-10 fertilizer and a 4- to 6-inch-layer of compost.

While planting, you can use 1/3 cup of fertilizer for every 25 square feet. It should be spread near the base of the plant and lightly watered into the soil for better and slow absorption.

Treating Diseases And Pests

Most leaf diseases come from wet or dirty water. As such, you should be careful in watering the plants and surrounding humidity.

If the plant shows signs of disease, such as discolored leaves, you need to prune them with alcohol-soaked scissors to prevent them from spreading to other parts and throw them in a covered trash can.


So the question “Why is my basil turning yellow with brown spots?” has an answer. There are many reasons why the leaves of this plant change color, such as overwatering, disease, lack of nutrition, or bad habitat.

To overcome these problems, you should pay careful attention when watering and providing nutrients to the soil before and during the crop.

Hopefully, some of the above information can help you better understand your garden and take better care of it.

Last Updated on October 13, 2023 by admin