Basil leaves turning yellow is a serious problem that is due to improper watering, poor lighting, nutrient deficiency, insect infestation, and disease attack. Fortunately, you can fix this problem if you know the causes.

Basil Leaves Turning Yellow

Please continue reading to know details about the reasons that cause yellowing and how to deal with them easily.

What Are the Reasons That Basil Plant Leaves Turn Yellow?

The reasons basil leaves turn yellow are adding inadequate water, providing incorrect lighting conditions, and weather stresses. Moreover, deficiency and over-adding of nutrients can also cause discoloration in leaves. In some cases, insect attack and disease damage can also cause basil leaves to change their color to yellow.

– Water Stress

Basil plants need the proper amount of water to thrive. If you don’t follow the watering schedule and the soil dries, problems will occur. It is because plants’ physiological processes and nutrient uptake depend on the moisture available in the soil.

So, mineral uptake and processes like photosynthesis, transpiration, and evaporation will only happen if the soil is moisture-less. This will weaken the plants, and the effects will be visible on the leaves.

– Extra Moist Soil

Just like dryness, excess water around the roots is not desirable either. Again, the oxygen supply gets restricted when there is lots of moisture on the root hairs. As a result, roots will feel suffocated.

When this happens, the water and nutrient uptake won’t be normal, and the physiological processes will take a hit. Ultimately, leaves will start to change their color to yellow and drop off.

– Light Stress

When you notice basil leaves turning yellow at bottom, then chances are the plant is facing light stress. Basil plants need light for around 6-7 hours to continue performing photosynthesis – a process critical for energy production. If you grow them where less light falls, photosynthesis won’t happen, and an energy shortage will occur.

Since leaves are the main site where most photosynthesis occurs, they will start to become yellow. But everything will happen gradually in case of light stress. First, you will see your basil leaves turning light green. If you don’t change their spot, plants will finally have yellow leaves.

Sometimes, you have placed pots in a well-lighted area, and still, light stress occurs. It happens because of overcrowded plants. You should ensure no plant is casting shade on the nearby plants if you want them to avoid facing lighting stress.

– Heat Stress

Yellow leaves can also be the outcome of temperature stress. Basil plants love temperatures between 50-80 degrees Fahrenheit. If it exceeds the limit, plants can face heat stress, which is never desirable.

Causes of Basil Leaves Turning Yellow

In heat stress, the water in the leaves starts to evaporate quickly, leading to dryness and wrinkles. The moisture-less leaf cannot perform physiological processes and eventually become yellow.

– Cold Temperatures

Just like heat extremes, low temperatures also cause problems for basil. The reason is that cold surroundings can freeze the moisture in the leaves or impact evaporation. This causes yellowing and stunted growth.

– Disease Damage

Basil leaves turning yellow and brown is also a sign of a disease attack. Basils are prone to lots of plant diseases. Generally, they are affected by fungi, but bacterial diseases can also damage them.

Root rot is a common basil disease. It occurs when you add more water than required for a long time. The fungi first attack the root, causing it to rot. The effect can also move upward to the stem and leaves too.

In addition to Root rot, downy mildew is another common disease that leads to the yellowing of basil plants. In this, you will also see brown spots on the leaves. If downy mildew gets severe, the affected leaves will drop off, giving an unaesthetic look to a plant.

Fusarium Wilt is another fungal disease that affects the Xylem vessels of plants. These vessels carry water, so plants affected by this disease face drought stress (even if you apply water). In this disease, leaves turn yellow with black spots or lesions in severe cases.

When it comes to bacterial diseases, bacterial leaf spot is a common one that plants face. In this, the leaves start having big yellow patches first. After some time, the whole section can get yellow and fall off.

Can you eat yellow basil leaves affected by diseases? No, it would be best if you did not consume such leaves. They are usually safe for human consumption, but the yellowing makes them taste bitter. So, it is better to avoid eating them.

– Pest Infestation

Why are my basil leaves turning black is a question you will ask yourself if you don’t control the pest infestation. You will likely see Aphids, Japanese Beetles, slugs, and snails on basils.

When aphids attack, they leave sooty mold on the black leaves. In addition, these pests feast on the leaves, which reduces the sap. When this happens, chlorophyll gets depleted, and leaves become yellow.

– Lack of Nutrients

Basil leaves yellowing can also be caused by nutrient or mineral deficiencies. Plants need minerals to carry out physiological processes at a normal rate. Lack of them affects their speed, which ultimately causes energy shortages in plants.

It’s no secret that plants low on energy cannot maintain leaf shape and color. First, the yellow patches start to emerge. After some time, the leaves become wrinkly and curl up. If you don’t apply fertilizers, they will finally fall off.

– Over-fertilization

Yellowing basil leaves is also an indication of over-fertilization. Just like deficiency, adding an excess of minerals harms the plants too. It is because soil can get toxic, which may burn the root hairs. If this happens, roots won’t be able to do their role.

Another reason to avoid over-fertilization is that the soil pH changes when you overflood soil with nutrients. The pH must stay in the optimal range of 6.0 to 7.5. If it doesn’t, then the nutrient lock will happen.

The nutrient lock is a condition in which roots won’t uptake minerals, even if you apply more doses. As a result, there will be a mineral deficiency in basil, which will cause leaves to become yellow. So, how to fix yellow basil leaves?

What Are Easy Solutions To Treat Basil Leaves That Are Yellowing?

The easy solutions to treat basil leaves that are yellowing are to add sufficient water and ensure they grow in a well-lighted area. It is also critical to apply organic fertilizers to avoid nutrient complications. If insects and diseases cause the yellowing, uproot weeds and apply appropriate sprays.

– Add Enough Water

If you don’t want leaves to become yellow, ensure the potting mix has sufficient moisture. Plants hate both bone-dry and overly moist soil. So, you must apply adequate water only.

The best practice is to check whether there is any moisture in the soil. If there is, then let it dry before you add water. Also, ensure you fill the pot with water, or else overwatering can occur.

– Let the Plants Enjoy Light

When basil leaves turn pale, ensure the plant receives proper light. It would be best to grow basil in those spots where it can get light for at least six hours. Also, over-exposure to light could be better too. Provide shade if you sense light intensity is more for a long period.

Similarly, if you have put the pots indoors, ensure proper growing conditions too. Use LED Grow lights to provide proper lighting to the potted basil plants. If you don’t have led lights, place plants near a window.

– Add Fertilizers Sufficiently

It is crucial to add sufficient fertilizers to grow basil properly without any yellowing of leaves. Both deficiency and over-adding can harm the plant in different ways, including the discoloration of leaves.

Remedies for Basil Leaves Turning Yellow

It is better to use organic fertilizers, like Compost. It is because these do not cause toxicity or change the soil pH. But if the plant is a lot weaker with more yellow leaves and you are sure you last applied fertilizers a while ago, then go for chemical fertilizers as they release nutrients more quickly.

– Go for Insecticides

To control the insect population, you should use organic repellents like insecticidal soap, baking soda, and wood ash. It is also a good option to spray neem oil to eliminate unwanted pests. Furthermore, you can handpick the beetles, slugs, and snails too.

Use chemical insecticides if the above-discussed methods don’t provide the desired result. Make sure to follow the proper application instructions printed on the label to avoid complications.

– Control Diseases

When diseases attack basil, you must act immediately. You should first cut off any infected part and put it in a sealed bag. Then, throw this bag away far from the plants. In addition, you should maintain proper distance between two plants to improve the air passage.

Furthermore, replace the potting soil if the disease spread does not stop. It would be best to put the infected pots separately from the healthy plants to control the spreading of disease. If nothing works, go for fungicides and bactericides.

Another critical thing to do is to keep the garden free from weeds—many diseases spread through these unwanted plants. Moreover, clean off any dirt, debris, or pet feces as soon as possible, as these things can also play their role in the spread of bacteria. Following these care tips will protect your plants from disease damage.

Conclusion of Basil Leaves Turning Yellow


You now know why basil plant leaves become yellow and how to fix this problem. Here are our final thoughts to summarize key points:

  • Apply sufficient water to maintain the green color.
  • Ensure leaves get proper light for seamless physiological functions.
  • Use organic fertilizers like compost to enrich the soil with vital minerals.
  • Don’t let insects and diseases damage plants. If they do, tidy the garden, uproot weeds, and apply appropriate sprays.

Doing this thing will keep the leaves green as they should be!

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