Tomato plant leaves turning yellow is one of their most common tendency, but not without a solution. Growing tomatoes is generally relatively easy, but when this discoloration does appear, it should cause concern.Tomato Plant Leaves Turning Yellow

Read on as we will explore the key reasons why our garden’s favorite plants turn yellow and give you insight into how to address them effectively. Many diseases can leave yellow leaves, so it is important to understand their causes and keep an open eye.

Why Are Tomato Plants Leaves Going Yellow?

Tomato plant leaves are going yellow because the seedling leaves are naturally yellow, or due to watering issues, or the soil is too compact. It could also be due to transplanting shock, or infection of a disease, nutrient instability, end of growing season, or not enough sun.

Tomatoes are an absolute delight to grow in the garden. These tender perennials have become a garden favorite because of their simplicity of growth and high yields. With thousands of varieties, you can find a tomato plant that best suits your taste and the climate.

Tomatoes are not immune to diseases, however, but yellow tomato leaves are one of the most common situations all gardeners deal with, so keep an open eye on these.Yellow Leaves of Tomato Plants

– Seedling Leaves Are Yellow

Tomato growing usually starts with developing little seeds in controlled environments and nurturing seedlings before they can be safely transplanted into the ground. These little seedlings usually have a few sets of leaves that often go yellow and fall without harming the plant.

If you’re a novice grower and noticed that your store-bought seedlings have the first few leaves going yellow, there’s no reason to worry. These are called cotyledons and aren’t considered to be “real leaves,” and this is why you should look at them as a baby’s first teeth, sustaining the plant to the point where it’s ready to push strong growth and be replanted in soil.

– Watering Issues

Incorrect watering is the first real culprit of yellow leaves on your tomatoes. It’s no wonder considering how many gardeners do this step wrong. Remember that oftentimes, it’s not about the lack of water that’s been given, but rather the overabundance of it.

Too often, we are led by the notion or concept of how plants need water and will be fine. Well, that’s only partially correct — plants need to take a breather from drinking now and again. Too much water can cause roots to suffocate and rot, preventing them from sending fresh oxygen to the plant cells, causing yellow leaves before they eventually drop off and look unhealthy.

– Soil Too Compact

Inadequate aeration is one of the most prevalent causes of leaf discoloration in any plant. But for this, don’t consider keeping your plants in well-ventilated areas. On the contrary, it has a lot of relation with the soil and the air that the roots receive.

If your soil is too compact, not only will roots have trouble moving through it, but they won’t be able to breathe as well. When the roots don’t have access to fresh air in the soil, they cannot send enough of it up the plant, and the plant struggles as a result.

The most simple way to determine if the soil is too compact is to observe the topsoil when watering. If the water has trouble quickly passing into the ground and stays up there for more than a few seconds, your soil isn’t breathing properly.

– Transplanting Shock

Recent transplanting can be the reason for leaf discoloration too. If you’ve transplanted your plants within two or three weeks of yellow leaves occurring, this is a reason why you are likely dealing with this transplant shock.

One must usually grow tomatoes from seeds and tomato seedlings that are first developed in a controlled, heated environment. After they show some signs of strength, we only place them into garden soil.

On this note, transporting the plants from warm and controlled environments to the ground that still gets cold overnight can make them go yellow in parts. Nothing to be afraid of, though; this will only make them stronger, and you should see them recover fast.

– Tomato Diseases

Several diseases can have tomato leaves turning yellow, and are mostly fungal type, and most of them will come from previously mentioned causes. It’s quite likely that some of your plants will catch any of these during the growth period, but don’t despair the fact that they are quite easy to deal with.

Early blight is the most common one of them and usually activates with too much moisture in and around the plant in the early stages of development of these fruits. It will start as pale yellow spots before the leaves turn yellow completely with bigger brown patches.

Septoria leaf spot typically starts as brown spots, similar to a cigarette accidentally burning through a shirt, with yellow leaf curl developing as a consequence. This disease is limited to tomato leaves at the beginning but can be fatal to the entire plant if left untreated.

Wilts are another type of tomato plant disease you should be worried about. Fusarium wilt usually starts in the roots, further preventing them from supplying the plant with nutrients, water, and air. Verticillium wilt is similar to blight, but the effects can be much faster. Finally, we have the bacterial wilt, as this one is often triggered by the bacterium typically found in sandy soils, so if you’re nurturing tomatoes in a clay-type soil, you should be fine.

– Nutrient Instability

Macro or micronutrient availability will be massively important when growing your tomato crops. Not only will they enable healthy development, but they will also help the plant when combating diseases.

Nitrogen deficiency isn’t something you want to deal with, as it aids in the healthy development and growth of the plant. Magnesium deficiency won’t allow for proper photosynthesis and the production of chlorophyll.

In contrast, an iron deficiency can itself cause yellow tomato leaves, and render them too weak to fight off those diseases. If your tomato plant is beginning to show signs of yellowing leaves, but its veins are still green, then you’re probably dealing with a nutrient deficiency.

– End of Growing Season

Natural lifecycle plays a big part! If you’re seeing your tomato plants starting to whither away, and they are beginning to droop, you should probably check the date. If it’s the end of the summer, then they’re getting ready to die off and let their spot to younger generations.

– Not Enough Sun

Tomatoes, like any plant out there, are natural-born sun lovers. However, they can get damaged by spending too much time in the midday sun. This is why you must note that more sun is always preferred, and if you’re growing your tomatoes in too shaded of an area, then yellowing leaves are due to the location they are placed in, and how the lack of us is not permitting photosynthesis to take place.

How To Prevent Tomato Leaves from Turning Yellow?

To prevent tomato leaves from turning yellow, you must begin to use fungicides and opt to place more organic fungicide options. You can also ensure the soil is well draining, and improve the watering regime, place the right nutrients, and make sure to fight pests.Preventing Tomato Leaf Yellowing

Prevention is your best bet when striving to keep your tomatoes alive and kicking. Organic fungicides, companions, and friendly insects are here to aid you and fix these issues naturally.

– Use Fungicides

Any of those fungal diseases can cause unsightly spots all over your beautiful plants. You can easily treat them with some trusty fungicides from your local garden center. Be mindful, because these can also be pretty intense on your plants and the environment. In short, it is best to go for a more natural solution, as there are numerous commercial options to choose from to keep those diseases out.

As a Pro tip, you must know that if you want your plants to show some natural strength, there are tomato varieties specifically bred to be able to withstand different types of wilts and leaf spots. They’ll probably be more expensive to get your hands on, but they will ensure healthy crops at the end of the season.

– Opt For Organic Fungicides

If you wish to abstain from using any chemical-based fungicide, you can have a homemade one by mixing in some baking soda, neem, and horticultural oils are all fantastic choices. Dilute them with water and give your plants a regular spritz throughout the growing season. These natural goodies have amazing properties that’ll send those pests and diseases packing.

– Place Well-draining Soil

It’s about more than finding a nice spot in the sun, and you need to be very keen regarding the soil and its texture, so make sure you go for a potting mix that’s not all clay to achieve proper drainage and give those roots the air they need. This will help prevent fungal and bacterial infestations as the water will not stay still.

Fungi love to hang out in moist and stale conditions, and this is important to create some airflow above the ground level too. So think of it like giving your plants a little breather. Spacing your tomato plants a few feet apart will lead them to have plenty of room to spread comfortably, without getting in each other’s way.

– Improve Your Watering Regime

Tomato plants sure do like to be irrigated, but be very detailed not to overdo it — especially if it’s the rainy season. If mother nature already has everything under control, let your plants be and avoid watering tomato plants before they need it.

However, you must be specific and wait until the soil becomes dry to the touch when you place your finger in there. This way, you’ll avoid creating a damp and cozy environment that fungi can’t resist. Remember how a little patience goes a long way to keep those tomato plants happy and healthy.Tomato Plants Care 2

– Place the Right Nutrients

You must either pay attention to the nutrition or go completely overboard with it. The goal here is to stay balanced and take nutrition as a valuable part of the tomato plant’s growth. When feeding your plants, always use commercial fertilizer and guide yourself by the instructions on the packaging.

– Fight Pests With Nature

Pests like gnats, aphids, and even potato beetles will all leave our leaves yellow in practically no time. But before you opt for that aggressive pesticide solution, you can call some pests to your aid as well. Plant tomato plants next to some companion plants, like flowers and other flowering beauties that will call ladybugs, lacewings, butterflies, and bees to your help.


So, what should you do if you notice these yellow spots on your tomato plants, here’s a quick tip to know what we covered:

  • Tomatoes grow in erect and ascending stems covered in sticky, dense hairs. Their compound leaves grow in an alternating pattern and can reach up to 10 inches long with serrated edges.
  • First, take a closer look and try to determine if it’s a fungal disease or an elemental problem. If it’s a fungal-related issue, the spots will change color and spread in a regular pattern over time.
  • One of the most frustrating issues is those pesky yellow spots that can creep on us out of nowhere as sun and cold damage, on the other hand, will have a more immediate impact.
  • To treat your plants, be sure to remove any damaged parts and step up your fungicide game.
  • To prevent diseases from appearing in the first place, opt for seedlings that have been bred to resist these types of ailments.

With all this information at your fingertips, you’ll be well-equipped to handle those frustrating yellow spots like a pro!

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