How to Fix Yellow Leaves on Tomato Plants?

Tomato leaves turning yellow due to aging is not a big deal.

But, if the leaves of your Tomato plants turn yellow at a young age, fix them by knowing the problems first.

So, if you also grow yellowed Tomato Plants, do not hesitate to read this article.

Is It Normal for Tomato Plant Leaves to Turn Yellow?

Some leaves on Tomato Plants turn yellow right after being bought from the nursery, probably due to unhealthy competition among seedlings.

You can fix that by giving your plant enough space and sunlight to grow and trim the damaged leaves.

On the other hand, the leaves on Tomato plants turn yellow during fruit-bearing to shift nutrients in fruit production, which is less of a problem.

Likewise, the leaves turn yellow and brittle at the end of their season to pave the way for another seasonal growth.

Altogether, every yellowing has its reason behind it and can be a normal phenomenon of its lifecycle.

But if yellowing occurs in the middle of the growing season or affects the fruiting, that’s not normal.

What Causes Yellow Leaves on Tomato Plants

A yellow is not good in Tomatoes if occurred other than normal processes that can lead to curling, spotting, and dropping of leaves.

So, you need to understand the signs of the Tomato Plant to understand the exact cause.

1. Improper Watering

As a gardener, we might mistake the watering intervals based on the spot as the water requirement of potted and garden tomatoes is different.

Overwatered soil blocks the passage of oxygen to different parts of leaves, and the lack of oxygen turns them yellow.

While underwatering, the flow of nutrients from the root part gets obstructed due to the absence of water.

And the deficiency of both water and nutrients hits the Tomato leaves hard, turning them yellow.

Immediate Steps of Revival

• In the overwatering case, shift the pot in the area receiving direct sunlight and let it dry.
• If the soil is beyond fixing, consider shifting the entire plant to new soil and removing some rotted roots, if any.
• Move the plant into a shady place if it faces underwatering conditions.
• Water the underwatered plants slowly from the bottom, allowing the roots to absorb it but not letting the water runoff.

2. Improper Lighting

The Tomato plant demands light in both the fruiting and growing stages.

In extreme light, the leaf gets sunburned, appears scorched, and ends with wilting.

Meanwhile, low light or shades hampers the normal photosynthesis process causing the lively green leaves suddenly turn yellow.

Immediate Steps of Revival

• If you live in the USDA zone with warmer temperatures, use a shade cloth during extreme summer.
• Remove any weeds near the plant to prevent the shade from falling upon the Tomato Plant.
• Change the location of the potted Tomato if it is under the shade. Keep it near a southwest-facing window.
• You can also set up grow lights in case of dark rooms for at least 12 hours.

3. Fertilization Problem

Fertilizers determine the Tomato plant’s health, but any fluctuation in fertilizer supply significantly affects the plant’s growth and resistance capability.

Yellowing leaves can exist due to the deficiency of nitrogen and potassium or micronutrients like magnesium, iron, and calcium.

Besides, excess supply also turns the Tomato plant yellow as the salts accumulate in the soil, halting nutrient absorption. 

However, deficiency affects the Tomato plant more than excess fertilizer, causing yellow leaves.

Practical Solutions

• Make the soil moist 1 day before fertilizing so that the soil can absorb the nutrition better.
• You can also use organic fertilizers like worm castings and manures to replace chemical fertilizers.
• Alternatively, use Burpee and Miracle-Gro for better results.
• Always feed your plants in actively growing seasons.

4. Transplant Shock

Most of us start our Tomato seedlings indoors and later transplant them outdoors.

But while transplanting, most of us forget to check the fluctuation in the day and night temperature as seedlings take time to adapt.

And minor negligence from our side causes transplant shock to the seedlings of Tomatoes leading to yellow bottom leaves.

The yellow leaves on Tomato Plants will not be a subject of worry if they shed themselves and grow healthy leaves.

But if they do not, then revive them as soon as possible.

Immediate Steps of Revival

• Apply a mixture of 1 tablespoon of regular granulated sugar and half a gallon of water.
• Provide shade to the plant if it is too hot during the daytime and supply water regularly to let them overcome the shock.
• While transplanting, check if the soil has warm and the night temperature does not drop below 50ºF.
• Keep your hands out of the reach of the roots of Tomatoes, as they have delicate roots.
• Trim off the yellow leaves to help the plant shift the entire focus on the growth of new green leaves instead of dying.
• If you can do nothing, try to avoid giving any extra stress to the plant and let it recover by itself.

5. Improper Soil pH

As the main base for the growth, the soil should be in its optimum health to not cause yellowing and wilting of leaves.

If any quality of the soil changes, like compaction or turning acidic or alkaline over time, your Tomato Plant will surely turn yellow.

Compact soil makes your Tomato roots suffocate, not allowing the flow of oxygen, nutrients, and water and ultimately causing yellow leaves.

Similarly, any change in the pH leads to infertile soil that cannot sustain the plant and causes the leaves to turn yellow and drop.

Immediate Steps of Revival

• First, use a test kit to check if your soil has turned acidic or alkaline.
• Treat your soil with Garden lime as instructed in the packaging for highly acidic soil.
• For alkaline soil, use organic compost to recover but do not overdo or else the compost will affect the nitrogen content in the soil.
• Mix sands in your soil if they appear clayey and compact.

6. Common Pests

Tomatoes have several enemies starting from the seedling stage to cause the yellowing of leaves.

You might wonder if the pests only cut and make holes in the leaf, but the pests feed on the sap of leaves.

Moreover, sap-sucking obstructs the water and nutrients that reach the leaves of the Tomato Plant. Due to the blockage, the leaves ultimately turn yellow and die.

The yellowing caused by pests is limited to the area they feed on, and you can check for infestation.

Immediate Steps of Revival

Here is a list of pests causing yellow leaves in Tomatoes with their signs and solutions.

You can also try washing your plants under running water and immediately exposing them to the sunlight.

By doing so, you can remove the larvae and baby of the pests and prevent infestation.

7. Bacterial and Fungal Diseases

Gardening challenges can occur when fungal or bacterial diseases fall in love with your Tomatoes.

Diseases can affect the plants from the bottom because they are primarily soil-borne. 

And it can be challenging to handle if the infestation reaches its severity. 

Immediate Steps of Revival

To start the treatment, you should know which bacteria or fungus is causing your Tomato leaves to turn yellow.

You can take the table below to understand the symptoms with their solutions hand to hand.

You can also remove the debris from the previous cropping to control the diseases attacking Tomato Plants.

Should I Remove Yellow Leaves from Tomato Plants?

YES. Trailing Tomatoes turn yellow over time as a growth phase, so you can pinch and snip off the leaves.

Yellowing can damage the top leaves of the determinate type, affecting the entire plant’s growth. So you must be careful while plucking the yellow leaves. 

Follow the steps to remove yellow or dead yellow leaves safely.

• Look out for dry weather to cut the leaves to prevent fungus from spreading over healthy leaves.
• Sterilize the scissors or shears with isopropyl alcohol to start the pruning.
• Look out for the bottom yellow leaves and the leaves touching the soil.
• Cut the bottom leaves from their lower branches but be careful not to hurt the main stem.
• Also, you can use your fingers to clip off if the number of yellow leaves is less.
• Throw the leaves in garbage far away from the plant to prevent fungus growth in the soil near the plant.

Look at the video if you have any confusion!

How To Prevent Yellow Leaves on Tomato Plants

You can avoid all the troubles occurring in the Tomato Plant by providing optimum care from the start.

Follow the steps below to ensure your Tomato Plant is lush and green in its growing season!

• Provide Tomato Plants with 6-8 hours of direct sunlight.
• Try to keep the humidity within the range of 65-85%.
• Tomato, as a summer crop, cannot withstand frost. So keep the temperature between 21-25ºC to get the best quality fruit.
• Offer an inch of water weekly during the growing stage and twice weekly during the fruit-bearing phase.
• So apply fertilizer with the ratio of 10-10-10 N-P-K before the growth begins and 5-10-10 N-P-K before the fruit sets.
• Choose a loose, sandy loam and well-draining soil with a pH of 6.0-7.0.

• You can start pruning the leaves after the flowers have set for fruiting and follow the second and third pruning every 10-14 days.
• You can transplant the Tomatoes when they attain three times the height of the container in a pot size of at least 24 inches deep and 20 inches across.