Why Are Your Tomato Leaves Turning Brown?

1. Overwatering

Overwatering is a common cause of brown leaves in tomato plants. When tomato plants receive excessive amounts of water, it can lead to root rot and other water-related issues, causing the leaves to turn brown. Here are some key points to understand about overwatering:

  • Causes: Overwatering can occur due to poor drainage, frequent and excessive watering, or using containers without drainage holes. It can also be a result of heavy rainfall or improper irrigation practices.
  • Symptoms: The leaves of overwatered tomato plants may turn brown, starting from the edges and progressing towards the center. The affected leaves often become soft and mushy. Additionally, overwatering can lead to wilting, stunted growth, and the development of fungal diseases.
  • Prevention and Treatment: To prevent overwatering, ensure that the soil is well-draining, and water the plants only when the top inch of soil feels dry. Use containers with drainage holes and avoid excessive watering. If overwatering has already occurred, adjust your watering schedule, allow the soil to dry out between waterings, and improve drainage. Consider using a fungicide if fungal diseases have developed as a result of overwatering.

2. Underwatering

On the other hand, underwatering can also cause brown leaves in tomato plants. When tomato plants do not receive enough water, they may become stressed and exhibit symptoms such as browning of the leaves. Here are some key points to consider about underwatering:

  • Causes: Underwatering can happen due to inadequate watering frequency, insufficient water volume, or poor irrigation practices. High temperatures, windy conditions, or sandy soils can also lead to faster water evaporation, increasing the risk of underwatering.
  • Symptoms: The leaves of underwatered tomato plants may turn brown, starting from the edges and progressing towards the center. The browning can be accompanied by wilting, dryness, and a general lack of vigor. The plant may also produce fewer flowers and fruits.
  • Prevention and Treatment: To prevent underwatering, establish a regular watering schedule and monitor the soil moisture levels. Water deeply and thoroughly, ensuring that the water reaches the plant’s root zone. Mulching the soil around the plants can help retain moisture. If underwatering has occurred, increase the frequency and volume of watering, and monitor the plant’s response. Reviving a severely underwatered plant may require additional care, such as providing temporary shade or misting the leaves to increase humidity.

3. Nutrient Deficiencies

Nutrient deficiencies can also contribute to the browning of tomato leaves. When tomato plants lack essential nutrients, their ability to carry out vital functions is compromised, resulting in brown and unhealthy foliage. Here are some key points to understand about nutrient deficiencies:

  • Causes: Nutrient deficiencies can occur due to imbalanced soil conditions, inadequate fertilization, or poor nutrient uptake by the plant’s roots. Factors such as high soil pH, excessive rainfall, or certain cultural practices can also influence nutrient availability.
  • Symptoms: Different nutrient deficiencies can manifest with specific symptoms. For example, a nitrogen deficiency may cause older leaves to turn brown and exhibit yellowing between the veins. A potassium deficiency can lead to brown or scorched leaf edges. Similarly, deficiencies in calcium, magnesium, or other essential nutrients can result in browning and discoloration of the leaves.
  • Prevention and Treatment: To prevent nutrient deficiencies, conduct a soil test to assess the nutrient levels and pH. Based on the results, amend the soil with organic matter or appropriate fertilizers to provide a balanced nutrient supply. Regularly monitor the plant’s overall health and address any signs of nutrient deficiencies promptly. Foliar sprays or targeted fertilization can help correct deficiencies in specific nutrients. It’s important to follow the recommended application rates and timing provided by experts or the soil test report.

4. Fungal Diseases

Fungal diseases can cause browning and discoloration of tomato leaves. Various fungal pathogens can infect tomato plants, leading to leaf spots, blights, or other symptoms that result in brown foliage. Here are some key points to consider about fungal diseases:

  • Causes: Fungal diseases in tomatoes are often favored by warm and humid conditions, poor air circulation, high soil moisture, and the presence of fungal spores. Overcrowding of plants, improper sanitation, and contaminated tools or equipment can also contribute to the spread of fungal diseases.
  • Symptoms: Fungal diseases can cause brown spots, patches, or lesions on tomato leaves. The affected areas may have a fuzzy or powdery appearance, indicating the presence of fungal growth. As the disease progresses, the affected leaves may wither, curl, or die prematurely. In severe cases, the entire plant can be affected.
  • Prevention and Treatment: To prevent fungal diseases, provide adequate spacing between tomato plants to ensure good air circulation. Avoid overhead watering, as wet leaves create an ideal environment for fungal growth. Apply a layer of mulch around the plants to prevent soil splashing and reduce the chances of fungal spores reaching the leaves. If fungal diseases are already present, remove and destroy the affected plant parts promptly. Fungicides may be necessary for severe infections, but it’s important to choose products labeled for tomato plants and follow the instructions carefully.


Brown leaves on tomato plants can be caused by various factors such as overwatering, underwatering, nutrient deficiencies, and fungal diseases. It’s important to identify the underlying cause and take appropriate measures to address the issue. By providing optimal watering, ensuring proper nutrition, and implementing preventive measures against fungal diseases, you can help maintain healthy tomato plants with vibrant green foliage. Regular monitoring, timely intervention, and good gardening practices are key to preventing and managing the browning of tomato leaves.


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