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Why Are My Tomato Plant Leaves Turning Yellow? Find Out Now

Dr Ahsanur Rahman, PHD

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Why are My Tomato Plant Leaves Turning Yellow
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Tomato plant leaves turn yellow due to various reasons, such as nutrient deficiencies, overwatering, pests, or diseases. It is important to identify the specific cause to effectively address the issue and prevent further damage to the plant.

Yellowing of tomato plant leaves can be a cause for concern for gardeners. Tomato plants rely on their leaves for photosynthesis and overall health, so any changes or discoloration can be alarming. There are several possible reasons why tomato plant leaves may turn yellow, including nutrient deficiencies, overwatering, pests, or diseases.

By understanding the underlying cause, gardeners can take the necessary steps to address the issue and ensure their tomato plants’ continued health and productivity. We will explore why tomato plant leaves turn yellow and provide solutions to help rectify the problem.

Tomato vine leaf heading toward decay

Common Causes Of Yellow Tomato Plant Leaves

Common causes of yellow tomato plant leaves include nutrient deficiencies, such as nitrogen or magnesium, overwatering, fungal diseases like early blight or fusarium wilt, and environmental stressors like excessive heat or cold temperatures. Proper watering, adequate fertilization, and disease prevention measures can help mitigate these issues and restore the health of tomato plants.

Nutrient deficiencies:

  • Lack of nitrogen: When tomato plants lack nitrogen, their leaves turn yellow. Nitrogen is essential for leaf growth and a scarcity of it can result in stunted plants.
  • Lack of iron: Iron deficiency can cause yellowing of tomato plant leaves, especially in regions with alkaline soils. Iron is crucial for chlorophyll production, and a deficiency can lead to pale, yellow leaves.
  • Lack of magnesium: Magnesium deficiency can result in yellowing older tomato leaves while the veins remain green. Magnesium is necessary for photosynthesis; without it, the plant cannot produce enough energy.
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Why Are My Tomato Plant Leaves Turning Yellow? Find Out Now 16

Overwatering and poor drainage:

  • Excessive watering: Overwatering can cause the roots to become waterlogged, leading to nutrient deficiencies and root rot. This can result in yellowing of the leaves.
  • Inadequate drainage: If the soil does not drain well, excess water can accumulate around the roots, suffocating them and causing yellowing of the leaves.

Environmental stress:

  • Extreme temperatures: Extreme heat or cold can stress tomato plants, causing their leaves to turn yellow. Providing adequate shade or protection during hot summers or cold winters is essential.
  • Excessive sunlight: Too much direct sunlight can scorch tomato leaves, causing them to turn yellow and eventually die off. Providing partial shade or using shade cloth can help prevent this.
  • High humidity: Tomatoes are susceptible to fungal diseases in high humidity. These diseases can cause yellowing of the leaves and other symptoms such as spots or wilting.

Pests and diseases:

  • Aphids and other insects: Aphids and other pests can sap the nutrients from tomato plants, leading to yellowing leaves. Additionally, some insects can transmit diseases that result in yellowing and curling of the leaves.
  • Tomato yellow leaf curl virus (TYLCV): Tylcv is a viral disease that causes yellowing, curling, and stunting of tomato plant leaves. Whiteflies transmit it and it can have severe impacts on plant health.
  • Fusarium wilt: Fusarium wilt is a fungal disease that causes yellowing and wilting of tomato plant leaves. It is soilborne and can persist in the soil, affecting multiple plants.

Cultural practices:

  • Improper pruning techniques: Pruning tomato plants incorrectly can stress them and cause yellowing of the leaves. It is important to follow proper pruning guidelines to maintain plant health.
  • Overcrowding of tomato plants: Crowded tomato plants can compete for nutrients and sunlight, leading to yellowing of the lower leaves. Providing adequate spacing between plants can help prevent this.
  • Lack of air circulation: Poor air circulation can contribute to high humidity and the spread of fungal diseases. It is important to space plants and provide adequate garden ventilation properly.

Identifying the specific cause of yellowing tomato plant leaves is crucial for implementing the appropriate solutions. Regular monitoring, proper care, and timely interventions can help keep your tomato plants healthy and vibrant.

Nutrient Deficiencies: Possible Underlying Causes

Discover the underlying causes of nutrient deficiencies that can lead to yellowing leaves on your tomato plants. Learn how to fix yellow leaves and promote healthy growth without using commonly overused methods.

Lack Of Nitrogen:

  • Nitrogen is an essential nutrient for tomato plants as it is crucial to their overall growth and development.
  • Without an adequate nitrogen supply, tomato plants may experience stunted growth and yellowing leaves.
  • Symptoms of nitrogen deficiency in tomato plants include pale yellow leaves starting from the bottom of the plant and progressing upward.

How to fix nitrogen deficiency in tomato plants:

  • Use a nitrogen-rich fertilizer or compost to provide the necessary nutrients for your tomato plants.
  • Apply the fertilizer according to the manufacturer’s instructions, making sure to cover the entire root zone of the plant.
  • Consider using organic sources of nitrogen, such as fish emulsion or blood meal, to promote healthier growth sustainably.

Lack Of Iron:

  • Iron is another crucial nutrient for tomato plants, as it is involved in essential processes like chlorophyll synthesis and energy production.
  • When tomato plants lack sufficient iron, they may exhibit yellowing leaves with green veins, a condition known as iron chlorosis.
  • Factors like high soil pH, excessive phosphorus levels, or poor root function can cause iron deficiency.

How to correct iron deficiency in tomato plants:

  • Adjust the pH of the soil by adding elemental sulfur or acidifying fertilizers to make iron more available to the plants.
  • Avoid over-fertilizing with phosphorus, as it can interfere with iron absorption by the roots.
  • Consider using chelated iron fertilizers, which are more easily absorbed by the plants and can quickly correct iron deficiency.

Lack Of Magnesium:

  • Magnesium is an essential macronutrient for tomato plants, as it is necessary for chlorophyll production and enzyme activation.
  • When tomato plants lack magnesium, their older leaves may turn yellow while the veins remain green, a condition called magnesium deficiency.
  • Factors like acidic soil, excessive potassium levels, or poor nutrient uptake can cause magnesium deficiency.

Treatment for magnesium deficiency in tomato plants:

  • Apply magnesium sulfate (Epsom salt) to the soil around the base of the tomato plant, following the recommended application rate.
  • Consider adjusting the pH of the soil to a more neutral range, as soil acidity affects magnesium availability.
  • Use balanced fertilizers that contain magnesium to provide a consistent supply of this essential nutrient to your tomato plants.

Remember, ensuring an adequate supply of nutrients like nitrogen, iron, and magnesium is crucial for maintaining healthy tomato plants. Addressing these nutrient deficiencies promptly, you can help your tomato plants thrive and produce a bountiful harvest.

Overwatering And Poor Drainage: Effects On Tomato Plants

Overwatering and poor drainage can cause yellowing leaves on tomato plants. Excessive water can lead to root rot and nutrient deficiencies, resulting in yellow foliage. Ensuring proper watering and improving drainage can help prevent this issue.

Overwatering and poor drainage are common culprits behind yellowing tomato plant leaves. Both issues can lead to waterlogged soil, depriving the roots of oxygen and causing plant stress. In this section, we will explore the effects of excessive watering and inadequate drainage on tomato plants and ways to prevent and improve these conditions.

Excessive Watering:

Excessive watering can harm tomato plants, impacting their overall health and productivity. Here are some signs that your tomato plant may be receiving too much water:

  • Yellowing leaves: Overwatered tomato plants often exhibit yellowing leaves, starting with the lower leaves and gradually progressing upwards. This yellowing can be accompanied by wilting or drooping foliage.
  • Root rot: Waterlogged soil can promote the growth of harmful pathogens, such as fungi and bacteria, leading to root rot. Affected plant roots may appear brown, mushy, or have a foul odor.
  • Stunted growth: Excessive moisture can inhibit nutrient uptake and hinder root development, resulting in stunted growth and smaller fruit production.
  • Increased susceptibility to diseases: Overwatered plants are more prone to diseases, such as powdery mildew and fungal infections, due to the favorable conditions created by excess moisture.

To prevent overwatering:

  • Check the moisture level: Before watering, use your finger to gauge the soil’s moisture content. If the top inch of soil feels dry, it’s time to water. Avoid watering if the soil is still moist.
  • Water deeply and infrequently: Instead of frequent, shallow watering, provide a deep soak once or twice a week to encourage robust root growth. This will also help the plants become more resilient to drought conditions.
  • Use mulch: Applying a layer of organic mulch around the base of tomato plants can help conserve moisture and regulate soil temperature, preventing excessive evaporation and water loss.

Proper Watering Techniques For Tomato Plants:

To ensure healthy tomato plants and prevent overwatering, follow these proper watering techniques:

  • Water at the base: Direct the water at the bottom of the plant, aiming to keep the foliage dry. This reduces the risk of fungal diseases and allows the water to reach the root zone directly.
  • Water in the morning: Watering in the morning allows the plants to dry out during the day, reducing the chances of fungal growth. It also ensures that the plants are hydrated before the temperature rises.
  • Use a watering can or drip irrigation: Avoid using high-pressure hoses or sprinklers that can splash water onto the leaves. Instead, use a watering can or implement drip irrigation for precise and controlled watering.

Inadequate Drainage:

Inadequate drainage is another common issue that can cause yellowing tomato plant leaves. When excess water cannot freely drain away, it accumulates in the soil and suffocates the roots. Here are some signs of poor drainage:

  • Pooled water: If you notice standing water around your tomato plants after watering or rainfall, it indicates poor drainage.
  • Soil compaction: Soil that becomes compacted, heavy, or clayey can prevent proper water drainage and result in soggy conditions.
  • Foul odor: Soil with poor drainage may emit a foul smell due to the presence of anaerobic bacteria that thrive in saturated conditions.

Improving drainage in tomato plant containers:

  • Add drainage holes: Ensure containers have sufficient drainage holes at the bottom to allow excess water to escape.
  • Use well-draining soil: Opt for a high-quality potting mix specifically formulated for container gardening. Avoid heavy, clay-like soils that can restrict drainage.
  • Elevate containers: Place containers on pot feet or bricks to raise them slightly above the ground, allowing excess water to drain more efficiently.
  • Use a layer of gravel or pebbles: Adding a layer of gravel or pebbles at the bottom of the container can help facilitate drainage and prevent waterlogged conditions.

By addressing overwatering and poor drainage issues, you can promote the health and vitality of your tomato plants, ensuring they thrive and produce an abundance of delicious fruits. Remember to maintain a balanced watering routine and provide adequate drainage for optimal growth.

Environmental Stress: Impact On Tomato Plant Health

Discover the impact of environmental stress on the health of tomato plants and why their leaves may be turning yellow. Explore the possible causes and learn effective strategies for maintaining vibrant, thriving tomato plants.

Tomato plants are susceptible to various environmental stresses, which can adversely affect their health and lead to yellowing of the leaves. Understanding the impact of extreme temperatures, excessive sunlight, and high humidity on tomato plants is crucial for maintaining their well-being.

Let’s explore each factor in detail:

Extreme Temperatures:

Tomato plants are sensitive to extreme temperatures, both high and low. Here’s a look at how these temperature extremes affect tomato plants:

  • Effects of high temperatures on tomato plants:
  • High temperatures can cause wilting and yellowing of tomato leaves.
  • Excessive heat can hinder the uptake of nutrients, leading to nutrient deficiencies.
  • Heat stress can reduce flower formation and fruit set in tomato plants.
  • Effects of low temperatures on tomato plants:
  • Cold temperatures can cause yellowing and curling of tomato leaves.
  • Frost and freezing temperatures can damage tomato plants, resulting in stunted growth and poor fruit production.
  • Cold stress can inhibit the plant’s ability to absorb water and nutrients, leading to nutritional deficiencies.

To protect tomato plants from extreme temperatures, consider the following measures:

  • Protecting tomato plants from extreme temperatures:
  • Use shade cloth or row covers to provide some relief from intense heat or cold.
  • Plant tomatoes in well-draining soil to prevent waterlogging that can exacerbate cold stress.
  • Consider using mulch to regulate soil temperature and moisture levels.

Excessive Sunlight:

While tomato plants need sunlight for photosynthesis, excessive sunlight can lead to a common problem known as sunscald. Here’s what you need to know:

  • Sunscald: A common problem in tomato plants:
  • Sunscald occurs when excessive sunlight damages the tomato fruit and leaves.
  • The affected areas appear yellow or white and may develop into sunken, leathery patches.
  • Sunscald can reduce fruit quality and overall plant health.

To protect tomato plants from excessive sunlight and prevent sunscald, follow these guidelines:

  • How to protect tomato plants from excessive sunlight:
  • Install shade covers, such as umbrellas or shade cloth, in areas where the plants receive intense sunlight.
  • Prune the tomato plants to ensure proper airflow and reduce the risk of sunscald.
  • Apply a layer of organic mulch around the plants to reduce soil moisture loss and regulate temperature.

High Humidity:

High humidity can also impact the health of tomato plants. Here’s what you should know about its effects and how to manage it:

  • Effects of high humidity on tomato plants:
  • High humidity creates a favorable environment for foliar diseases such as blight and mold.
  • Excessive moisture can lead to root diseases and rot in tomato plants.
  • Humidity can hinder the airflow around the plants, increasing the risk of fungal infections.

To manage humidity levels in tomato gardens and prevent related issues, follow these tips:

  • Tips for managing humidity in tomato gardens:
  • Choose tomato varieties that are more tolerant of high humidity.
  • Provide adequate spacing between plants to promote airflow and reduce humidity buildup.
  • Water tomato plants at the base to minimize moisture on leaves and prevent fungal infections.

Remember, creating a suitable environment for tomato plants by addressing extreme temperatures, excessive sunlight, and high humidity is crucial for preventing yellowing of leaves and ensuring their overall health. By implementing these measures, you can enjoy healthy, vibrant tomato plants with lush green leaves and abundant fruit production.

Pests And Diseases: Identifying And Treating Tomato Plant Issues

Yellowing tomato plant leaves can be a sign of nutrient deficiencies or diseases. To treat this issue, prune away the yellow leaves and fertilize the plants regularly, paying attention to magnesium levels.

Aphids And Other Insects:

  • Tomato plants are susceptible to various insect pests, such as aphids, whiteflies, and tomato hornworms.
  • Aphids are small, soft-bodied insects that feed on the sap of tomato plants, causing leaves to yellow and distort.
  • Whiteflies are tiny, white-winged insects that suck sap from tomato plants, leading to yellowing leaves and stunted growth.
  • Tomato hornworms are large green caterpillars that can devour tomato plant foliage, causing leaves to turn yellow and wilt.

Common Insect Pests That Affect Tomato Plants:

  • Aphids: These small insects cluster on the undersides of leaves and suck sap from the plant.
  • Whiteflies: These tiny white-winged insects congregate on the undersides of leaves, leaving behind sticky honeydew.
  • Tomato hornworms: Large green caterpillars that can quickly strip the leaves from tomato plants.

Natural Remedies For Controlling Insect Infestations:

  • Neem oil: A natural insecticide that can be sprayed on tomato plants to deter aphids and other pests.
  • Insecticidal soap: A solution made from water and mild soap that can suffocate and kill aphids and whiteflies.
  • Ladybugs: Release ladybugs onto tomato plants as they feed on aphids and other small insects.
  • Beneficial nematodes: These microscopic worms attack and kill soil-dwelling pests like tomato hornworms.

Tomato Yellow Leaf Curl Virus (Tylcv):

  • Tylcv is a viral disease that affects tomato plants, causing yellowing leaves, curling, and stunted growth.
  • It is transmitted by the silverleaf whitefly, which feeds on infected plants and then spreads the virus to healthy ones.

Symptoms And Spread Of Tylcv:

  • Yellowing of leaves, starting from the base of the plant and progressing upwards.
  • Leaf curling, leaf shrinkage, and reduced fruit production.
  • Tylcv can spread through infected plant debris, contaminated gardening tools, or nearby infected plants.

Preventing And Managing Tylcv Infections:

  • Plant resistant varieties: Choose tomato varieties that are resistant to tylcv.
  • Sanitation: Remove and destroy infected plants and debris to prevent the virus from spreading.
  • Control whiteflies: Use yellow sticky traps and insecticidal soap to catch and kill whiteflies.
  • Crop rotation: Avoid planting tomato plants in the same spot every year to reduce the risk of infection.

Fusarium Wilt:

  • Fusarium wilt is a soil-borne fungal disease that affects tomato plants, causing yellowing, wilting, and eventual plant death.
  • It is caused by the fungus fusarium oxysporum, which infects the roots of tomato plants.

Causes And Symptoms Of Fusarium Wilt:

  • Soil contamination: The fungus can persist in the soil for several years, infecting tomato plants.
  • Yellowing and wilting of lower leaves, starting from one side of the plant.
  • Brown discoloration of the vascular tissue, visible when the stem is cut open.

Controlling Fusarium Wilt In Tomato Plants:

  • Use resistant varieties: Choose tomato varieties that are resistant to fusarium wilt.
  • Practice crop rotation: Avoid planting tomatoes in the same soil for at least three years.
  • Improve soil drainage: Ensure proper drainage to prevent waterlogged soil, which can promote fungal growth.
  • Use fungicides: In severe cases, fungicides can be applied to the soil to suppress the fungus.

Cultural Practices: Managing Yellowing Tomato Plant Leaves

If you notice yellowing tomato plant leaves, it could be due to cultural practices such as insufficient sunlight, overwatering, or nutrient deficiencies. Properly managing these issues can help revive your plants and promote healthy growth.

Improper pruning techniques:

  • Over-pruning tomato plants can lead to yellowing leaves.
  • Pruning should be done strategically to avoid stress on the plant.

Importance of pruning tomato plants:

  • Proper pruning helps improve air circulation and sunlight penetration.
  • It promotes the growth of healthy foliage and reduces the risk of diseases.

Proper pruning methods to prevent yellowing leaves:

  • Remove lower branches and sucker shoots.
  • Use clean, sharp pruning shears to make clean cuts.
  • Maintain a balanced shape by removing excessive growth.

Overcrowding of tomato plants:

  • Planting too many tomato plants close together leads to competition for resources.
  • Lack of adequate space can result in yellowing leaves and reduced yield.

Negative effects of overcrowding on tomato plant health:

  • Restricted airflow creates a favorable environment for diseases and pests.
  • The lack of sunlight penetration can hinder proper leaf development.

How to properly space tomato plants:

  • Space tomato plants at least 2-3 feet apart to allow sufficient airflow.
  • Provide adequate room for each plant’s root system to grow.
  • This spacing allows better sunlight exposure and minimizes competition for nutrients.

Lack of air circulation:

  • Poor air circulation around tomato plants can lead to yellowing leaves.
  • Stagnant air traps moisture, promoting fungal diseases.

The importance of air circulation for tomato plants:

  • Proper airflow helps to dry the foliage quickly after rainfall or irrigation.
  • It reduces the risk of diseases caused by high humidity.

Improving air circulation in tomato gardens:

  • Trim neighboring plants to ensure they don’t impede airflow.
  • Use stakes or trellises to support tomato plants, keeping them upright.
  • Consider spacing tomato plants properly to allow for better ventilation.

You can effectively manage yellowing tomato plant leaves by implementing cultural practices such as proper pruning techniques, avoiding overcrowding, and improving air circulation. Remember to regularly monitor your plants and adjust as needed to maintain their health and productivity.

Frequently Asked Questions

How Do You Fix Yellow Leaves On Tomato Plants?

To fix yellow leaves on tomato plants, prune away the affected leaves to redirect the plant’s energy to new growth. If only a few yellow leaves are at the bottom of a well-established plant, there’s usually no cause for concern.

However, if the yellowing is widespread, it could indicate a nutrient deficiency. In such cases, consider providing the plant with proper fertilization. Epsom salts can be used to address yellowing caused by magnesium deficiency. Young tomatoes may require fertilization every two weeks, whereas container-grown tomatoes may need fertilization every two to four weeks.

Ensuring the plants receive adequate sunlight, proper watering, and well-drained soil can also help prevent the issue of yellow leaves. Remember, it’s always essential to monitor the plant’s overall health and address any underlying issues promptly.

Should You Remove Yellow Leaves From Tomato Plants?

You don’t need to worry about yellow leaves on tomato plants as long as the plant is growing new leaves. Simply prune away the yellowing leaves to allow the plant to focus on new growth. If you only see a few yellow leaves at the bottom of a mature plant, it’s usually not a cause for concern.

Does Overwatering Cause Tomato Leaves To Turn Yellow?

Overwatering can cause tomato leaves to turn yellow.

How Do I Add Nitrogen To My Tomato Plants?

To add nitrogen to your tomato plants, you can use fertilizers formulated explicitly for nitrogen supplementation, such as compost, manure, or synthetic fertilizers with a high nitrogen content. Apply the fertilizer to the soil around the base of the tomato plant, ensuring not to touch the stem or leaves directly.

Water the plant thoroughly after applying fertilizer to help it absorb the nutrients. Repeat this process every few weeks throughout the growing season to maintain a steady nitrogen supply for your tomato plants. Additionally, consider planting legumes as companion plants for your tomatoes, as legumes can fix nitrogen in the soil.

This can naturally enhance the nitrogen levels available to your tomato plants. Regularly monitor your plants for signs of nitrogen deficiency, such as yellowing leaves, and adjust your fertilization routine accordingly.


To conclude, it is important to understand that various factors can cause yellowing leaves on tomato plants. Identifying the underlying issue is crucial in order to provide the appropriate treatment. One common cause of yellowing leaves is nutrient deficiency, particularly a lack of magnesium.

Applying Epsom salts can help alleviate this issue. Overwatering or underwatering can also lead to yellow leaves, so it’s essential to maintain proper moisture levels. Diseases such as tomato yellow leaf curl virus and fusarium wilt can also result in yellowing foliage.

Carefully monitoring and providing preventive measures against these diseases is important for maintaining healthy plants. Pruning away yellowing leaves can redirect the plant’s energy towards new growth. Remember, if only a few lower leaves are affected, it may not be a cause for concern.

Understanding the causes and implementing appropriate measures can ensure your tomato plants remain vibrant and productive.

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