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Why Are Your Basil Leaves Turning Yellow? It Could Be One Of These 5 Reasons!


Who does not like the flavor of basil? It is used so extensively in cooking because of the way it enhances the taste of any dish. It is also called great basil and belongs to the family of mints.

Native to central Africa’s regions to Southeast Asia, Basil is a tender plant with many varieties. Its name comes from the Latin ‘Basilius,’ which loosely translates to the ‘kingly plant.’

It is an easy plant to grow in your garden. However, a common issue of basil leaves turning yellow is something you may face while growing this multi-purpose plant. Sometimes you would be left scratching your head and asking why are your basil leaves turning yellow!

Read on to learn more about this.

Basil In The Kitchen Garden

Do you have basil in your kitchen garden? It is one of the most commonly grown and used herbs around the world. When I first started my kitchen garden, I was excited that I would be able to use fresh, organic herbs regularly.

However, I noticed that the leaves on my basil plants were turning yellow. I thought that the plants were drying and started to water them more often.

They got worse, and I was ready to throw them out! Luckily, a friend who knows a lot about basil saw the plants and told me that I was overwatering the plant.

This is what was causing the leaves to turn yellow. My friend also told me that there were many other reasons why basil leaves may turn yellow. Soon my plants revived and became healthy.

It was after this that I decided to share all that I have learnt about this wonderful plant.

Watch this video for more information.

What Is Special About Basil?

Basil is an attractive herb not only used for culinary purposes but also medicinal uses. It is the flavor and aroma of its leaves, and can be used both fresh and dry, which is its USP.

A warm-weather, fragrant herb, basil is the mainstay of many dishes, including the mouth-watering Pesto. The plant yields an abundant harvest within weeks and will keep growing as you pluck the leaves.

Apart from flavor and fragrance, basil has many other excellent properties.

  • It is a powerful antioxidant. It shields the body from cell-damaging free radicals.
  • Promotes blood flow because it is a good source of magnesium
  • Good source of Vitamin A and Vitamin K
  • Anti-inflammatory effect with eugenol
  • Basil also has calcium and omega-3 fatty acids.
  • Basil oil is used for making essential oils that can be used to treat cuts, wounds, acne, etc.
  • Basil essential oil is also used in aromatherapy to treat mental fatigue, depression, migraines, tension, etc.

So, next time you are eating delicious pasta, you can eat it without feeling too guilty, thanks to basil. That is one thing on your plate which you can enjoy without thinking twice.

Types of Basil

Whether you are buying basil from a shop or cultivating it in your backyard, there is nothing like a little sweet basil added to any dish.

Basil plant has many varieties, and some can cultivate up to 2 or 3 feet in height. The shape and taste of the leaves on the different basil plants also differ a lot. Some of the most well-known and used basil varieties are

Sweet Basil

This is the most frequently found type of basil in the USA. The leaves are smooth and bright green. Genovese basil is a kind of sweet basil, and the two are quite similar.

It has a more delicate floral fragrance. It is best to remove the buds to encourage the leaves to keep growing.

Sweet Basil
Sweet Basil

Thai Basil

As the name suggests, this basil is very widespread in Thailand, Cambodia, Vietnam, and many other far eastern countries in the region.

This basil has a spicy aroma and is usually supplementary to stir-frys at the last minute. It adds wonderfully pleasing anise and clove-like flavor.

It may seem a bit spicy when raw, but once cooked, it is quite mild. With dark maroon branches and specked leaves, this plant stands tall.

Thai Basil
Thai Basil

Holy Basil

Most often used in India for religious as well as medicinal purposes. Its stem is furry, and the leaves are green or purple. Its scent is very strong and is not used for cooking.

Both green and purple varieties are used in many religious rituals, which is why it is known as holy basil. The thin and tender leaves can be easily crushed for home remedies for the stomach, throat, and many other ailments.

Holy Basil
Holy Basil

Fino Verde Basil

Sometimes referred to like the spicy globe basil, it is ideal for kitchen gardens. The size of the leaves are smaller than those of sweet basil though they are similar in taste.

Fino Verde has an undertone of ginger. One unique thing about this variety is that the entire herb can be utilized in cooking, even the stems.

Fino Verde Basil
Fino Verde Basil

Opal Basil

One of the most attractive basil varieties, Opal basil, has profound burgundy colored leaves, stalks, and flowers. They are used in pasta and salads, mainly to add a dash of color and flavor. As the plant matures, you will notice that color also intensifies.

Opal Basil
Opal Basil

Lemon Basil

Who can resist a combination of lemon and basil flavors and aromas. You get the delicate tanginess of lemon along with the distinctive flavor of basil.

It works well when scrubbed onto chicken or fish before baking. It is best used to add flavor to teas, salads, dressings, and soups. You will find it mostly in Persian, Indonesian, and Thai cuisines.

Lemon Basil
Lemon Basil

Why Are Your Basil Leaves Turning Yellow?

Basil is quite a hardy plant and is suitable for growing around the year. Although this plant is generally trouble-free, certain things can cause it damage and turn the leaves yellow.

Some of the reasons why leaves turn yellow can be rectified very easily, while some are difficult, and some factors are incurable. It will also depend on the time of the season.

It is not an easy task to determine what is causing the leaves to turn yellow because it could be any of the following:

1. Over-watering

This is probably the simplest and most common reason why basil leaves turn yellow—these plants sunny weather and airy soil. If you notice the leaves turning yellow, you should look at the watering schedule first.

Basil thrives in soil which does not hold too much water. You should use water only when necessary. Check by inserting your finger into the soil.

Water only if the top couple of inches of the soil feel dry. If you notice that the soil remains wet for 1 or 2 days after watering, then you must consider the option of changing the soil. You can do this easily if you have planted the basil in a pot.

Ensure that the drainage holes are not blocked and remove the plate or saucer from under the plant to let the water drain properly.

2. Disease

Though basil is a tough plant, a disease or infection can cause some damage to it. Leaves turning yellow could also be due to some disease, and it is best to take care of it as soon as possible. Two of the most common diseases which can affect a basil plant are:

Root Rot

Generally a direct effect of over-watering. If you do not take quick actions and leave the soil with excess moisture, root rot can set in. It is caused by fungi that thrive in moist surroundings. It leads to mould and rot setting in the roots.

You must remember that root rot does not have remedy, but it is preventable. Once it sets in, it is best to remove the affected plant and keep it spreading to nearby plants.

You can prevent root rot by keeping the soil well-drained. Make sure to remove to excess mulch and add some gravel for better drainage.


Many plants are susceptible to this disease. Downy mildew is wind-borne, so it spreads easily and fast. If you notice the leaves turning yellow and see a greyish downy layer on the underside, it is downy mildew.

It loves a wet and humid environment where there is low ventilation. You can prevent it by being careful while watering. Make sure that you only water the plant at the base and leave the leaves dry.

3. Nutrient Deficiency

Many people believe that there is no requirement of fertilizing a herb because they can feed themselves! However, when you notice the leaves turning yellow, you know that something is not right.

You don’t have to frequently fertilize herbs; but, it is essential to make sure that they receive the required nutrients.

If you are growing basil in a pot, you can initially mix fertilizer and then check the plant’s health after 6 months. Depending on where you live, climate, condition of the soil, and the container’s size, you may have to fertilize them within a 3 months interval.

Overwatering is a problem because this washes the nutrients. Give the soil fertilizer treatment towards the end of every growing cycle. As far as possible, use organic compost for best results.

At the same time, if you over fertilize, you will notice increased production of leaves. It may look nice, but you will notice that the yield is less flavourful. EarthPods Premium Garden Herbs & Vegetable Plant Food is a fantastic fertilizer for herbs. You can try it on your basil plants.

EarthPods Premium Garden Herbs Vegetable Plant Food

4. Pests

Pests can bring a healthy plant down in no time. Though, unlike a disease, plants under pest attack can usually be salvaged. Pests on one plant generally mean that they are on all surrounding plants as well.

The most common pests which attack basil plants are:

  • Aphids: if you see a black substance on the back of the yellowing leaves and tiny little orange insects, then these are aphids. They suck the juice from tender leaves and stems, turning them yellow. These can be controlled easily with an insecticide.
  • Caterpillars: they feed on basil and damage the plant. Their attack can cause the leaves to turn yellow. Big caterpillars can be picked off by hand, or you can use Bt (Bacillus thuringiensis), a natural bacterium that targets these insects.
  • Nematodes: these are small, soil-dwelling pests and form small galls on the roots and cause the leaves to turn yellow. You cannot do much apart from harvesting the plant for healthy leaves. You may choose resistant varieties of the plant next time.
  • Mealy Bugs: these are white coloured, soft bugs which can turn the leaves yellow. They excrete a substance on the stem near the leaf nodes. You will have to use specific insecticides to get rid of these.

5. Temperature

Apart from the above-given reasons, temperature also plays an important part in keeping basil healthy. Chilly temperatures can turn the leaves of basil plants yellow.

The ideal temperature during the daytime should be above 70 degrees Fahrenheit. At night it should be above 50 Fahrenheit. Lack of sun also causes yellowing of leaves.

Six to eight hours of bright sunlight is preferable. You may have to use artificial lighting if you plan to keep the plant indoors.

Treating Diseases And Pests

The yellowing of leaves in basil is also a natural occurrence as the plant ages. This is something that happens with all plants.

However, if you notice the leaves turning yellow prematurely, then you need to assess the problem carefully. When it is a disease or pest which is causing this problem, then you can take these measures.

  • Some insects act as predators like ladybugs and green lacewings, and they will turn aphids and mealybugs into their meals. They can get rid of the pests for you.
  • Use neem oil instead of pesticides otherwise; you may end up harming the predators. Apply it near the base of the plant and some on the plant. Always be careful with the instructions and follow it thoroughly to get the best results.
  • Ants love the secretions of both aphids and mealybugs. They even carry these pests to surrounding plants, which causes more damage. Keeping the ant population down will help you in controlling aphids and mealybugs.
  • The system of a companion plant is also a good option. By planting basil around plants which the pests don’t like can help. Zinnias and garlic are two such plants. They release a strong odour that repels these pests. Mint and geraniums are also quite effective. You will find it a harmless and effective way of controlling pests.
  • If your basil plant is under attack from bacterial infections, then you may have to pluck off the infected parts to save the rest of the plant.
  • When it comes to fungal infections, prevention is the only option. Keeping the leaves dry and improving airflow will help in controlling such infections. Plant basil plants at least 18 to 24 inches apart. Remove the infected plant immediately and ensure no infected leaves are left behind.

How To Harvest Basil

There is no specific time or season to harvest basil. You just pluck some leaves when you need them. However, to keep the plant healthy and growing well, it is essential to harvest it regularly.

  • Even if you do not need it, harvest it regularly. About 1/3rd of the leaves can be harvested every month, depending on the size of the plant. Use as much as you can fresh or freeze for later use.
  • Snip the stem at the point where two large leaves meet. A good pair of hand shears will ensure a clean cut. This promotes new growth and a healthier plant.


Called the ‘king of herbs,’ basil is an easy-to-grow herb with a distinctive flavor and fragrance. It does not require much maintenance and grows well, even without too much care.

However, if you notice its leaves turning yellow, you need to show a little tender loving care to the plant. Keep these things in mind.

  • Regular watering with good drainage. Avoid overwatering. Too dry and too moist soil, both are a problem.
  • Basil requires very light fertilization. Just twice a season application is enough for the plant.
  • Pinch leaves from the tips of the plant as soon as you notice two sets of true leaves. This will make the plant bushy.
  • Companion plants are an option for keeping the pests away and making both the plants’ produce tastier. Garlic for pests and tomatoes and lettuce for flavor are good companion plants.

All in all, having basil at home in your yard or a container is always a great thing as far as using it in dishes is concerned. Look after the plant well and enjoy its benefits.