Why Are My Tomato Plant’s Leaves Turning Yellow and Brown?

August 27, 2026

Why Are My Tomato Plant’s Leaves Turning Yellow and Brown?

Yellowing and browning leaves are among the most common problems tomato gardeners face.

The good news is that not every yellow leaf is a reason to panic. In many cases, it’s simply part of the plant’s natural aging process. Other times, it can be a sign of watering issues, nutrient deficiencies, pests, or disease.

Learning to recognize the symptoms can help you solve the problem before it affects your harvest.

Here’s what to look for.

1. Natural Aging (The Most Common Cause)

If only the lowest leaves are turning yellow while the rest of the plant looks healthy, your tomato may simply be aging.

Sometimes, yellow leaves are simply part of the plant’s natural aging process.

As a plant grows, its oldest leaves—usually those near the bottom—may gradually turn yellow and eventually die off. The plant is reallocating resources as it continues producing new leaves, flowers, and fruit.

If it’s only a few of the oldest lower leaves turning yellow while the rest of the plant looks healthy and continues growing normally, there may be nothing to worry about.

You can remove leaves once they’ve yellowed or begun to die back, especially if they’re touching the soil. This can help keep the plant tidy and improve airflow around the base.

The important thing is to look at the overall pattern. A few aging leaves are normal. But widespread or rapidly progressing yellowing—especially when it affects newer growth or comes with spots, wilting, curling, or stunted growth—may point to another problem that needs attention.

Signs

Yellowing begins at the bottom of the plant
New growth remains green
Plenty of flowers and fruit
No unusual spots or lesions

What to Do

Simply remove the yellow leaves to improve airflow around the plant.

No treatment is needed.

2. Overwatering

Too much water prevents roots from getting enough oxygen.

Without healthy roots, the plant can’t absorb nutrients properly, causing leaves to yellow and eventually turn brown.

Signs

Yellow leaves throughout the plant
Soft stems
Wilting despite wet soil
Slow growth

How to Fix It

Water only when the top inch or two of soil begins to dry.
Improve drainage if water sits around the roots.
Avoid watering on a strict daily schedule.

After heavy rain, I make it a habit to check my container plants for standing water, especially my potted tomatoes.

Even if a container normally drains well, drainage holes can sometimes become blocked by compacted soil, roots, or debris. When that happens, water can begin pooling in the container and leave the roots sitting in overly wet soil.

If I notice water isn’t draining the way it should, I check the existing drainage holes first to make sure nothing is blocking them. Sometimes the solution is as simple as clearing the obstruction.

If the container simply doesn’t have enough drainage, adding additional drainage holes may be necessary. Just make sure you can safely drill or modify the type of container you’re using without damaging the plant or roots.

This is especially important after several days of rain. We tend to think about overwatering as something that happens when we water our plants too frequently, but Nature can overwater our containers too!

A quick inspection after a heavy rain can help catch drainage problems early and prevent plants from sitting in waterlogged soil for an extended period.

3. Underwatering & Drought Stress

Dry soil can also cause tomato leaves to turn yellow. When a tomato plant doesn’t receive enough water, it becomes stressed and may begin sacrificing some of its older, lower leaves.

The lower leaves may yellow first and eventually become dry, crispy, and brown if the plant continues experiencing drought stress. You may also notice wilting, curling leaves, or soil that has pulled away from the sides of a container.

This can happen especially quickly with container-grown tomatoes, since pots can dry out much faster than raised beds or in-ground gardens during hot and windy weather.

If I notice yellowing and suspect underwatering, I check the soil before automatically reaching for the watering can. Stick your finger a couple of inches into the soil and feel for moisture. If it’s dry, give the plant a slow, thorough watering so moisture can reach deeper into the root zone.

Signs

Dry soil
Wilted leaves during the day
Brown leaf edges
Blossom-end rot may also develop

How to Fix It

Water deeply and consistently rather than giving the plant frequent shallow drinks.

Mulching around tomatoes can also help reduce moisture loss and keep soil moisture more consistent. The goal isn’t to keep the soil constantly wet.

Tomatoes do best with consistent moisture, avoiding the repeated cycle of becoming extremely dry and then soaking wet.

4. Nutrient Deficiencies

Yellow tomato leaves can sometimes be a sign that the plant isn’t getting enough nutrients. Tomatoes are heavy feeders, and as they grow, flower, and produce fruit, they continuously pull nutrients from the soil.

The pattern of yellowing can sometimes give you clues about what might be missing. For example, some nutrient deficiencies appear first on older, lower leaves, while others are more noticeable on newer growth. You may also see discoloration between the leaf veins, brown edges, or stunted growth depending on the nutrient involved.

Nitrogen Deficiency

Signs:

Older leaves turn pale yellow first.
Overall slow growth.
Small plants.

Magnesium Deficiency

Signs:

Yellowing between leaf veins.
Veins remain green.

Potassium Deficiency

Signs:

Yellow edges that later become brown.
Browning begins around leaf margins.

How to Fix It

Before automatically adding fertilizer, consider the bigger picture. Check when you last fertilized, the condition and pH of the soil, and whether watering or drainage problems could be preventing the roots from taking up nutrients properly.

If the plant needs feeding, use an appropriate tomato or vegetable fertilizer according to the label directions. Adding compost or other suitable amendments can also help replenish nutrients over time.

More fertilizer isn’t always better. The goal is to identify what the plant needs and correct the imbalance rather than feeding it unnecessarily.

5. Early Blight

Early blight is a common fungal disease of tomatoes, and it often begins on the oldest leaves near the bottom of the plant before gradually moving upward.

One of the most recognizable symptoms is brown spots with concentric rings, which can give the spots a target-like appearance. The surrounding leaf tissue may begin turning yellow, and eventually the entire affected leaf can brown and die.

Because the symptoms often begin close to the soil, I regularly inspect the lower leaves of my tomato plants. Removing badly affected foliage can help slow the spread, and I avoid leaving diseased leaves around the base of the plant.

Signs

Brown spots with concentric rings (“target spots”)
Yellow halos around the spots
Leaves eventually turn completely yellow and die

How to Fix It

Remove infected leaves.
Avoid wetting the foliage.
Water at the base of the plant.
Improve airflow by spacing plants properly.
Mulch to reduce soil splashing.

Good garden practices can also help reduce the risk. Mulching beneath tomatoes helps reduce soil splash, while adequate spacing, pruning when necessary, and good airflow allow foliage to dry more quickly. I also try to water near the base of the plant instead of repeatedly wetting the leaves.

Early blight doesn’t necessarily mean your tomato season is over. Catching it early and removing affected foliage while keeping the plant healthy can help manage the disease and keep the plant producing longer.

6. Septoria Leaf Spot

Septoria leaf spot often becomes noticeable during periods of warm, wet, and humid weather, when conditions are favorable for the disease to spread.

Like early blight, Septoria commonly begins on the older leaves near the bottom of the tomato plant and gradually works its way upward. The leaves develop numerous small, round spots with darker margins and lighter gray or tan centers. As the infection progresses, the surrounding foliage can turn yellow, then brown, and eventually die.

Because Septoria and early blight can both cause yellowing and spotting on lower tomato leaves, it’s helpful to look closely at the spots. Septoria usually produces many smaller spots, while early blight is more likely to produce larger lesions with distinctive concentric, target-like rings.

Signs

Numerous small brown spots
Yellowing around the spots
Starts on lower leaves
Leaves eventually drop

How to Fix It

Remove affected leaves.
Avoid overhead watering.
Improve airflow.
Rotate crops each year.

Wet foliage can encourage the disease to spread, so I try to water tomatoes at the base, maintain good airflow around the plants, and mulch the soil to reduce splashing onto the lower leaves.

If I notice affected foliage, I remove the diseased leaves and dispose of them rather than leaving them underneath the plant. I also sanitize pruning tools between plants when disease is present.

You can’t control rainy or humid weather, but you can make the environment around your tomatoes less favorable for disease by improving airflow, minimizing soil splash, and keeping foliage dry whenever possible.

7. Fusarium or Verticillium Wilt

Fusarium wilt and Verticillium wilt are soil-borne diseases that interfere with a tomato plant’s ability to transport water through its vascular system.

As the disease progresses, you may notice yellowing and wilting that often begins on the lower leaves and moves upward. Sometimes symptoms appear more strongly on one side of the plant or even on one side of an individual leaf. Eventually, affected leaves may turn brown, dry up, and die.

Unlike a tomato that simply wilts because the soil is dry, a plant affected by vascular wilt may continue to look wilted even when adequate moisture is available.

Signs

Yellowing often starts on one side of the plant.
Leaves wilt.
Symptoms gradually spread upward.
Plants decline despite adequate watering.

What to Do

Unfortunately, once a plant is seriously affected, there isn’t a simple treatment that will reverse the infection. Removing badly diseased plants can help prevent leaving infected plant material in the garden. Prevention becomes especially important.

Choose resistant tomato varieties when possible, rotate crops, avoid moving potentially contaminated soil between beds, and keep garden tools clean. If you’ve had repeated problems with Fusarium or Verticillium wilt, look at the resistance codes on tomato seed packets or plant labels. Varieties marked with F and/or V resistance can provide another layer of protection.

Not every yellowing or wilting tomato has a soil-borne disease, though. Check watering, root health, and other possible causes before assuming wilt disease is the problem.

8. Pest Damage

Several tomato pests can cause leaves to turn yellow, so when I notice unexplained yellowing, I always take a closer look at the plant before assuming the problem is watering or nutrients.

Sap-sucking pests such as

aphids,
whiteflies, and
spider mites

feed on plant tissue and can cause yellowing, stippling, curling, or distorted leaves. Heavy infestations can weaken the plant and eventually cause damaged foliage to dry up and die.

Some pests are incredibly easy to miss. Spider mites, for example, are tiny, so you may notice the damage before you notice the pest itself. Fine webbing can be another clue when populations become larger.

This is why I make a habit of checking underneath the leaves, especially when I’m already walking around the garden. Look along the stems and growing tips as well. You may find clusters of insects, tiny eggs, webbing, sticky residue, or other signs that something has been feeding on the plant.

If I catch a pest problem early, it’s usually much easier to manage. Depending on the pest and severity, simply removing heavily infested leaves or spraying insects off with water may be enough. Other situations may require an appropriate insecticidal soap or other treatment labeled for the specific pest and edible crops.

The important thing is to identify the pest before treating the plant. Yellow leaves are a symptom, not a diagnosis, and taking a few minutes to inspect the foliage closely can help you figure out what’s actually causing the problem.

9. Too Little Sunlight

Tomatoes are sun-loving plants and generally grow best when they receive at least 6 to 8 hours of direct sunlight each day. When they don’t get enough light, plants may become:

Weak stems
Grow more slowly
Produce fewer flowers and fruits
Pale or yellow and eventually drop.

If you’re growing tomatoes in containers, one advantage is that you may be able to move the plant to a sunnier location as sunlight patterns change throughout the season.

For tomatoes growing in raised beds or in the ground, look at what might be blocking the light. Nearby plants can become much larger than expected by midsummer, so selectively pruning or repositioning surrounding vegetation may help more sunlight reach the tomato plant.

This is another reason I like to plan for the mature size of my plants, not just how small they are when I transplant them in spring. A garden that looks wide open in May can become very crowded by July!

Whenever possible, give tomatoes your sunniest growing space. More adequate sunlight means stronger growth and gives the plant the energy it needs to flower, develop fruit, and produce a good harvest.

10. Heat Stress

During prolonged heat waves, tomato plants can become stressed, especially when high daytime temperatures are combined with warm nights and dry soil.

One of the signs I often notice is leaf curling or rolling, where the leaves fold inward and sometimes take on a taco-like appearance. This can be the plant’s way of reducing the amount of leaf surface exposed to intense heat and limiting moisture loss.

Heat-stressed tomatoes may also wilt during the hottest part of the day, even when there is still some moisture in the soil. Flowers may drop, fruit production can slow, and leaves can begin yellowing or developing dry, brown areas if the stress continues.

During a heat wave, I pay extra attention to soil moisture because tomatoes—especially those growing in containers—can dry out much faster than usual. Deep, consistent watering and a layer of mulch can help keep the root zone moist and reduce extreme fluctuations in soil temperature.

Leaves may:

Curl
Turn yellow
Develop brown, scorched edges

If possible, providing some afternoon shade during extreme heat can also help, particularly for container-grown plants that can be moved or temporarily protected with shade cloth.

A little leaf curling during hot weather doesn’t automatically mean something is seriously wrong. Look at the entire plant and the conditions it has been experiencing. If the plant otherwise looks healthy and the leaves begin relaxing when temperatures improve, heat stress may simply be the plant responding to difficult summer weather.

11. Herbicide Damage

Tomatoes are extremely sensitive to certain herbicides, so even small amounts of lawn or broadleaf weed killers drifting into the garden can injure the plants.

Herbicide damage often looks different from typical nutrient deficiencies or watering problems. You may notice twisted or distorted new growth, curled leaves, narrow or “strappy” foliage, unusual cupping, and sometimes yellowing. The newest growth is often where the symptoms are easiest to see.

Damage can happen when herbicide spray drifts from a nearby lawn or garden, especially when products are applied on windy days. Tomatoes may also be exposed through contaminated grass clippings, compost, manure, or other materials containing persistent herbicide residues.

Symptoms include:

Twisted new growth
Curled leaves
Yellowing
Distorted stems

Unfortunately, once herbicide injury occurs, there isn’t a quick treatment that can undo the damage. Mildly affected plants may eventually produce normal new growth if the exposure was limited, while severely damaged plants may struggle to recover.

If you suspect herbicide damage, avoid adding unnecessary fertilizer or treatments before identifying the problem. Watch the new growth closely and consider where the exposure might have come from.

Prevention is especially important. Avoid spraying weed killers near tomatoes, be cautious about applying them on windy days, and know the source of any grass clippings, manure, or compost you bring into your vegetable garden.

How to Prevent Yellow and Brown Leaves

Healthy tomatoes start with good growing habits.

To reduce problems:

Plant in full sun.
Improve soil with compost.
Water deeply and consistently.
Mulch around plants.
Space plants properly.
Support plants with cages or stakes.
Water at the base of the plant.
Remove damaged lower leaves.
Rotate crops each year.
Inspect plants regularly.

These simple practices help prevent many common tomato problems before they start.

My Experience Growing Tomatoes

I’ve learned that it’s completely normal for a few lower tomato leaves to yellow as the season progresses.

When I see yellowing, I first check where it’s happening. If it’s only the oldest leaves near the bottom, I usually remove them to improve airflow and keep an eye on the rest of the plant.

If the yellowing spreads quickly or I notice dark spots or lesions, I inspect the plant more closely for disease or watering issues. Catching problems early has helped me keep my tomato plants productive throughout the season.

Quick Troubleshooting Guide

Final Thoughts

Yellow and brown tomato leaves don’t always mean disaster.

Many cases are simply the result of aging leaves or minor watering issues. The key is to look at the overall health of the plant, identify where the symptoms begin, and act early if you suspect disease or nutrient deficiencies.

Healthy soil, consistent watering, good airflow, and regular garden checks go a long way toward keeping tomato plants healthy all season long.

Frequently Asked Questions

Should I remove yellow tomato leaves?

Yes. If they’re old, damaged, or diseased, removing them improves airflow and helps the plant focus its energy on healthy growth.

Can yellow tomato leaves turn green again?

Usually not. Once a leaf has turned completely yellow, it rarely recovers. Focus on correcting the underlying problem to protect new growth.

Why are only the bottom leaves turning yellow?

This is often natural aging, especially if the rest of the plant looks healthy. It can also be an early sign of fungal diseases, so inspect the leaves for brown spots or lesions.

Does overwatering cause yellow leaves?

Yes. Overwatering can suffocate the roots, preventing them from taking up nutrients and causing yellow leaves.

Can heat cause tomato leaves to turn brown?

Yes. Extended periods of hot, dry weather can scorch leaf edges and cause browning, especially if the plants aren’t watered consistently.

How can I prevent tomato diseases?

Plant tomatoes in full sun, space them properly, water at the base of the plant, mulch the soil, rotate crops each year, and remove infected leaves promptly.