Why Are My Tomato Leaves Turning Yellow?

  • By: TheWalledNursery
  • Time to read: 5 min.
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Have you ever wondered why your tomato leaves are turning yellow?  

Tomato plants typically turn yellow because they lack nutrients. Some tomato plants turn yellow because they are experiencing poor plant care, like bad watering techniques, or they have been planted in inadequate soil.

Tomato leaves turning yellow guide
Tomato leaves turning yellow solution

If you want to reverse the effects of your tomato plants turning yellow, you must grow your tomatoes in the proper growing conditions, with nutrient-rich fertilizers and soil. 

Explore this article to learn why your tomato plants are turning yellow and whether you can reverse these plants.  

Why are my tomato leaves turning yellow? 

There are several reasons why your tomato leaves can turn yellow, like nutrient deprivation and poor watering habits.

In most cases, these can be treated and the yellowing can be reversed.

Tomato leaves turning yellow main reasons
Reasons behind tomato leaves turning yellow

However, there are also more drastic issues like pests and blossom end rot, which cannot be easily treated.  

Reasons your tomato leaves turn yellow include:  

  • Nutrient deprivation 
  • Sun scorching 
  • Blossom end rot 
  • Inadequate watering routines 

The most common reason tomato plants turn yellow is because your tomato plants do not have enough nutrients.

Nutrients often come from fertilizers and soil. When you do not choose the right soil or fertilizers, you might end up with yellow, nutrient-deprived leaves. 

Keep In Mind – Getting too much sunlight can also be a major problem for some tomato plants, causing them to change color and retain less water.

When you keep your tomato plant in direct sunlight, the soil is too dry to soak up water. It can be important to adjust your watering routine, so your plant gets more or less water. 

What nutrients can cause tomato leaves to turn yellow? 

Nutrient deficiency is the most common reason that your tomato plants are turning yellow.

Nitrogen, potassium, and magnesium are the most common deficiencies found in yellowing leaves.  

Tomato nutrient deficiency fix
Tomato nutrient deficiency

Nutrients that can cause your tomato plants to turn yellow include:  

  • Not enough potassium 
  • Nitrogen deprivation 
  • A lack of magnesium 
  • Iron deficiency 

These common problems all have different yellowing appearances, ranging between the inner and outer areas of the leaves.

Why Do Rose Leaves Turn Yellow?
Why Do Rose Leaves Turn Yellow?

It is important that you get a fertilizer with nitrogen, potassium, magnesium, and iron to help your tomato plant stay healthy. 

How can you reverse the yellowing of your tomato leaves? 

You can reverse the yellowing of your tomato plants by giving them more fertilizer and finding a new watering routine.

It is important that you find a nutrient-rich fertilizer so they can grow healthy again since tomato plants turn yellow because of nutrient deprivation. 

Reverse yellowing tomato leaves steps
Reverse yellowing tomato leaves

A new watering routine can establish better nutrient distribution and promote healthier growth.

A plant that has a poor watering routine will have difficulty growing to its fullest. 

Will sunlight cause tomato plants to yellow? 

Too much sunlight causes the yellowing of leaves.

This occurs if you plant or leave your tomatoes in direct sunlight for too long. Tomato leaves are vulnerable to the sun.

Works Well – Instead of keeping your plant in direct sunlight, you should use mesh above your plant or grow your tomatoes in a greenhouse to prevent yellow sunspots. 

Do soil conditions impact yellowing of tomato plants? 

Soil conditions impact yellowing of tomato plants since tomato plants require good soil to grow healthy plants.

Young tomato plant in the garden

It is important that your soil contains plenty of nutrients, with liquid fertilizers evenly distributed throughout.

If you want to reverse the yellowing of your tomato leaves, you must rejuvenate your unhealthy soil or replace it with fresh, compatible soil. 

How does watering impact the yellowing of tomato plants?  

A poor watering routine can cause your tomato plants to turn yellow.

It is important that you water your plants at the base of the plant so the roots can soak the water.

Watering from the top down can result in the roots not soaking up the water, leading to yellowing of roots. 

Watering tomato tips
Watering tomato

Water your tomatoes at the start of the day when it is the coolest. Watering your plants when it is hot may prevent the plant from soaking up enough water.

Avoid overwatering your plants by only watering your tomatoes if the soil is no longer wet or else you will cause damage to the roots.  

Is it bad for tomato plants to turn yellow? 

It can be bad for your tomato plants to turn yellow because it means your plant is nutrient deprived.

Your tomato plant may also be experiencing an issue like a pest infestation that should be treated immediately.  

Should you be worried when your tomato plants turn yellow? 

You should be worried about your plants turning yellow if you notice they are wilting.

Spotted wilt virus tomato facts

If your leaves are wilting, it could be a clear sign that your plants are close to dying because of a pest or poor plant care like watering or fertilizer issues. 

What does it mean when the outsides of the tomato leaves are yellow? 

When the outside of the tomato leaves are yellowing, it is a sign that your plants are deprived of potassium.

In Most Cases – You can find potassium in fertilizers. So, increase the fertilizer you give your plant and you should see a change in the color. 

Can blossom end rot cause your tomatoes to turn yellow? 

If your tomato fruit is experiencing blossom end rot, it can turn yellow and then black.

Blossom end rot tomato
Blossom end rot

Furthermore, the leaves around your tomato might begin to discolor. Discoloration can cause your green leaves to appear yellow.  

The blossom end rot cannot be fixed and will not go away on its own, so you should just shear away the dying leaves. 

What pests cause tomato plants to turn yellow? 

Pests such as spider mites and aphids can cause your tomatoes to turn yellow.

These insects will suck the sap from your leaves, causing the leaves to discolor. After the leaves have discolored they will eventually die and fall from your plant.  

It is important that you get treatment for your plant immediately if you notice any signs of mites or other pests.

Remove infected plants and keep them quarantined so the pests do not spread to other plants. 

Final Thoughts

Why are my tomato leaves turning yellow? Tomato plants typically turn yellow because they lack nutrients.

Nitrogen, potassium, and magnesium are the most common deficiencies found in yellowing leaves.  

You can reverse the yellowing of your tomato plants by giving them more fertilizer and finding a new watering routine.