Tomato Plants Leaves Turning Yellow: 7 Causes (Explained)

There are a variety of problems that can affect tomato plants, and today I’m going to discuss the issue that occurs most frequently and causes the leaves of tomato plants to turn yellow.

When this happens, it can be difficult for someone who is just starting out, but an experienced gardener can easily determine what is causing the problem and eliminate it. 

But it can be hard for a beginner to figure out where the problem is coming from. I have put together a list of seven possible causes that I have found in my own work and included them in this article.

You can’t get rid of this issue without addressing all seven of the causes that I’ve outlined in this article, so you can’t skip over them. I have also provided an explanation here regarding the solutions to the problems caused.

Why Are My Tomato Plants’ Leaves Turning Yellow?

The leaves of tomato plants can turn yellow for a number of reasons, but one of the most common is that the plant has received either too much or too little water. Pests, a lack of important nutrients, problems with transplanting, bad soil quality, diseases, and the end of the growing season are some other reasons.

Let’s move on to the factors that contribute to the yellowing of tomato leaves and discuss what causes them.

1. Improper Watering 

The most common cause of yellowing leaves on tomato plants is insufficient irrigation. Many gardeners water their plants incorrectly, either too little or too much.

Gardeners may overdo it on the care front in our efforts to keep the plants happy, supplying considerably more water than the plants truly require out of fear of the soil drying out.

Excessive wetness in the soil may suffocate the roots and cause them to rot. When the roots are harmed and there is less oxygen in the soil, the leaves turn yellow and fall off.

Improper watering can also induce yellowing in withering leaves. If the plant drowns, the leaf edges will become yellow and eventually fall off. If all the leaves on a tomato plant turn yellow and fall off, the plant may die.

Here I have explained 5 causes with solution here in other article which you can read by clicking here.


Watering patterns will very certainly reveal whether or not watering is the problem. You overwatered if you watered when the top layer of soil was still moist or if the earth became soggy.

Underwatering is the problem if the leaves are drooping and the plant is fighting to stay upright (or if you know you’ve skipped a watering session or two).

Watering your tomato plants correctly is critical to their health. Check the soil on a daily basis and only water when the plant truly requires it, which is generally after the top 1 or 2 inches of soil have dried up.

Water first thing in the morning to minimize evaporation and leaf damage. Water the soil thoroughly and around the roots rather than the leaves to stimulate deep root development.

If overwatering is the problem and it keeps happening, you may have a serious case of root rot.

Plant preservation is becoming increasingly difficult. After removing the decaying root portions, you can dig up the plant and replant it in new soil. Depending on how much of the root survives and how the plant develops, you may have to start over.

2. Pests

Pests, pests, and then more They may wreak havoc on our gardens, yet gardeners must deal with them year after year. Tomato plants attract a variety of pests, some of which cause tomato leaf yellowing.

Pests like aphids, thrips, hornworms, cutworms, spider mites, flea beetles, and whiteflies can cause symptoms that can be seen on tomato leaves. The most common reason is that bugs consume the sap trapped within the leaves.

This form of yellowing, unlike disease-related yellowing, is restricted to the site of infection (rather than starting from the bottom of the plant and moving up like disease).


The best way to avoid a pest infestation, and most of the reasons for insect infestation and leaves turning yellow that this article talks about, is to take steps to prevent them.

Making your garden a biodiversity hotspot will attract predatory insects, including ladybugs, lacewings, parasitic wasps, and spiders. They love eating the pests that eat your tomatoes! Invite them in and delegate the tough lifting to them.

By companion-planting your tomatoes, you can keep pests at bay. Plants like nasturtiums, marigolds, basil, and chives can deter and “trap” pests. Aphids, for example, will flock to mature nasturtiums before seeing your fresh tomato plants. 

If you want to try out companion planting this year, plant these flowers and plants a few weeks before your tomatoes. They must be huge enough to make an effect.

Manual pest treatment is another efficient, if time-consuming, method of getting rid of an infestation.

Aphids and whiteflies are easily knocked off stems and the undersides of leaves with a strong spray of water. 

Spider mites are so little that you may just pick the affected leaves if you notice them early enough. The idea is to spend time in your garden on a regular basis so that you can spot problems before they become emergencies.

3. Nutrient Deficiency

If none of the above causes your leaves to yellow, you may be nutritionally inadequate. This might be due to a lack of a particular macronutrient or micronutrient in the soil or to a problem with the plant’s ability to absorb that nutrient.

The principal macronutrient responsible for yellowing leaves is nitrogen.

Nitrogen is necessary for proper plant growth and leaf production. When the plant lacks nitrogen, the elder leaves turn light yellow. If the plant does not develop beyond this time, it is due to a lack of nitrogen.

A lack of certain micronutrients can also cause the leaves to turn yellow, a condition known as chlorosis. 

The tomato plant can’t make chlorophyll if it can’t get to photosynthetic minerals like magnesium, iron, sulfur, or zinc. As a result, the leaves become yellow while the veins remain vivid green.


Apply a general fertilizer if you detect a nutritional deficit. To compensate for soil deficiencies, most all-purpose fertilizers will include a nutritional balance.

To be sure, a soil test should be performed. This will help you figure out where the problem is coming from and give you a clear idea of how to fix it.

For example, a magnesium deficiency can be fixed by putting a mixture of Epsom salt and water on the leaves.

Without a soil test, you cannot be certain of a deficiency, and you may end up harming the plant even more by adding extra remedies.

A soil test will also tell if the problem is with the soil or the plant. Keep in mind that nutrient deficiencies in a plant are not always caused by a soil condition.

Rather than the soil, the problem is most likely with the plant’s roots, which are unable to carry nutrients throughout the plant.

If the soil test shows that there is no shortage, you should look at how you are watering and aerating the soil to fix the problem.

Nutrient deficiencies can cause tomato leaves to turn yellow as well as tomato plants to wilt. In another article of mine, I discuss 7 reasons why tomato plants begin to wilt, along with solutions.

4. End of season

Consider the time of year before running through any of these situations and making a million changes.

Is the tomato season coming to an end? If this is the case, yellowing leaves are not a reason for concern. Instead, they are a natural part of the plant’s life cycle and mean that production has stopped.

After the leaves begin to fall off, trim any new growth and dead leaves to encourage the ripening of the plant’s final fruits.

The first rule of gardening maintenance is to remain calm.

Based on the previous signs, your assessment of the plant, and how you take care of it, you should be able to tell which problem is most likely.

 A soil test will also reveal if the issue is with the soil or the plant. Remember that nutrient deficiency in a plant is not always the result of a soil condition. Most likely, the problem is because the plant’s roots can’t get nutrients to all parts of the plant.

If the soil test shows that there isn’t a shortage, you should look at how you water and aerate the soil to fix the problem.

5. Soil Quality

A similar problem happens when the soil around your tomato plants doesn’t get enough air.

The roots begin to suffocate as a result of a lack of oxygen. The roots are incapable of carrying oxygen, water, or other nutrients throughout the plant. As a result, the leaves become yellow, suggesting that the plant is dying.


You can aerate the soil by loosening it with your hands, depending on how well the roots are developed. However, this is likely to damage the root system and cause more issues. To completely avoid this issue, start the plant in healthy, organic-rich soil.

Because walking on the soil compacts it, growing tomatoes in raised beds or large pots is one option.

6. Transplantation

If you have just transplanted seedlings and see yellowing leaves on the bottom of the plant, transfer shock is most likely to blame.

Seedlings need time to adjust when they are moved from a warm place, like inside or in a greenhouse, to cold soil outside.

As a result of the shock, the plant’s bottom few leaves may become yellow. Fortunately, this is only a transitional period.

There is nothing to be concerned about as long as the new growth is green and healthy. The yellow leaves will ultimately fall off, and the plant will recover.


Because transplant shock is rarely detrimental to the plant and isn’t always repairable even when identified, it’s best to avoid it altogether.

Check that the soil has warmed and that overnight temperatures have not dropped too low before transplantation (below 50 °F).

If you see signs of transplant shock, like leaves turning yellow, take them off the stem to help the plant get better.

This redirects energy away from preserving withering leaves and toward much-needed new growth.

7. Disease

Disease is one of the most significant causes of yellowing leaves. Yellow leaves are caused by a range of tomato plant diseases, many of which are difficult to eradicate once established

The primary culprit is early blight, which is caused by a fungus in the soil. Fortunately, this issue is easily identified. 

On the lower leaves, a pale yellow spot will form and slowly grow into a dark brown area with yellow edges. If the leaf is not treated, it will become yellow and fall off.

Septoria leaf spot is another fungal disease that causes similar symptoms. Large brown spots on the leaves of infected tomato plants are linked by yellow patches. If the issue is not addressed, it has the potential to spread from the plant’s leaves to its stem.

Other wilts include fusarium wilt, verticillium wilt, and bacterial wilt.

Fusarium wilt hurts a plant’s roots, which stop water from getting to the stems and leaves. Even with wet soil, the plant will appear wilted, with leaves falling off from the base upward.

Verticillium wilt symptoms are similar to those of early blight and Septoria leaf spot. The lower leaves contain pale yellow spots with brown veins. These dark blotches will fade with time, as will the plant’s leaves.

Bacterial wilt is caused by a bacterium present in moist, sandy soils. This problem is common in plants that have been moved, but it usually doesn’t show up until later in the season.

 As the leaves turn yellow, the plant begins to wilt.


Any signs of sickness in your tomato plants must be handled right away. If you do not address the issue, it has the potential to spread to the rest of your plants and other sections of your garden.

Early blight and septoria leaf spot can be managed if found early. To keep unhealthy leaves away from other plants in your garden, remove and discard them. 

Apply a fungicide made to treat the problem. Carefully follow the product’s instructions until the problem gets better.

Unfortunately, if you see any of the three “wilts,” you must immediately kill the plant.

There is no cure for any of these ailments, and if given the chance, they will spread across your garden.

When removing an infected plant, make sure no other plants come into contact with it.

Even though there is no proven way to avoid health problems, you can take steps to lower your risk.

Choose disease-resistant kinds and allow each plant an adequate distance so that the leaves do not touch.

Clean your gardening tools often, and rotate your crops to keep the soil healthy.

Should I Remove Yellow Leaves From Tomato Plants?

So, you’re seeing some yellow leaves on your tomato plants. What’s the deal?

It’s natural to have a few yellow leaves on a tomato plant. In fact, it’s normal for the majority of the leaves to be green. So, unless the majority of the leaves are yellow, it’s best to just leave them alone.

Removing the leaves could do more harm than good, since the plant will need them to photosynthesize and create energy for growth. You could end up stressing out the plant and damaging it permanently.

Will The Yellow Tomato Plants Recover?

The short answer is yes, the yellow leaves on your tomato plants will recover, but there are a few things you can do to help speed up the process.

First, take a closer look at the leaves to see if they’re just starting to turn yellow or if they’ve already turned brown.

If they’re just starting to turn yellow, it’s likely a sign that your plant is experiencing a nutrient deficiency.

Adjust your watering schedule and continue to give your plants a good soak once a week.

If the leaves have turned brown, it’s likely that your plant is experiencing stress from either the heat or pests.

Move your plants to a cooler spot in your yard (or even bring them inside) and apply an insecticide to get rid of any unwanted pests.

What Do You Feed Yellow-Leaved Tomato Plants?

It’s hard to tell what’s wrong with tomato plants just by looking at the leaves. They can turn yellow for a variety of reasons, but most of the time it’s because of something the plant is being given to eat.

Fertilizer is a common culprit—either you’re giving it too much or you’re not giving it the right kind.

Over-watering can also cause yellow leaves, as can under-watering. And if your plant is getting too much sun, the leaves will start to turn yellow as well.


With the help of this post, you should be able to figure out the main reason why the leaves on your plant are turning yellow. If you follow the advice in this article, you will be able to solve the issue once and for all.