Why Are My Tomato Plant Leaves Turning Yellow? Easy Checklist!

Healthy plants should have green leaves from the bottom up if they are well cared for and not diseased.

The lower leaves of a tomato plant often turn yellow and die off as the plant grows. People generally do not fertilize tomatoes enough, which leads to nitrogen problems.

In addition to nutritional imbalances or disease outbreaks, other factors can also contribute to yellowing leaves.

Two times as much fertilizer is needed for tomato plants as for cucumbers. A lack of nitrogen will often cause older leaves to fall off. In order for the younger leaves to survive, older leaves provide nitrogen to them.

Leaf yellowing can also be caused by an iron deficiency but in younger leaves. On older leaves, magnesium deficiency causes yellow spots or speckles. You need to fertilize regularly for nitrogen, iron, and magnesium deficiencies.

Remember that when you use a lot of fertilizer, the plant also needs a lot of water. In order to find out how much water your tomato may need, you can place a finger several inches deep in the soil to test for moisture near the roots. Water the tomato plants more frequently as they mature, so if the soil feels dry, it’s time to water.
A soil moisture meter can also be used to determine when to water.

Don’t forget to spray regularly, even if you don’t think you need to. For fungus, fungicides are usually used as preventative measures rather than as curative measures. To prevent the disease from developing, gardeners will want to take a proactive approach before they see signs of disease. In most cases, it is too late to treat a disease once it has been detected. It is common for diseases caused by fungi or bacteria to cause yellowing.

Any excess mineral, including sodium chloride and table salt, can cause yellowing. Whenever you grow tomatoes in a container with salty water, water the container until it reaches out so that the salt can run through the soil and flush out. This will help in preventing the buildup of those salts within the container itself.

How Do You Fix Yellow Leaves On Tomato Plants?

The easiest way to determine if your soil is low in magnesium is to perform a soil test. But if you’re not able to do this for any reason, you can carry out a little detective work to figure out what’s ailing your tomato plants.

The condition known as interveinal chlorosis appears when magnesium is deficient. Because magnesium is an important nutrient for chlorophyll production, your leaves are chlorophyll-less. Trees’ leaves fade from green to yellow and red as their chlorophyll fades in the fall. This is not what you want to see on your tomato plants in the summer.

As time passes, a magnesium deficiency also causes leaves to turn red, purple, or brown, and chlorophyll levels decrease even further. Leaves that are older are more likely to be affected. There can be significant leaf loss, weakened plants, and poor fruit set in severe cases.

Interveinal chlorosis can also be caused by nutritional deficiencies, so it’s crucial to consider the factors that may precipitate a magnesium deficiency.

Most soils, except those with very poor soils, have plenty of magnesium. Plants cannot absorb magnesium efficiently when they are overfed with high-potassium fertilizers such as tomato feeds.

After heavy rains or overwatering, magnesium can easily be washed out of sandy or other very free-draining soils. Despite my tomatoes being planted outside, this summer was very dry, which prevented me from having this problem. 

A deficiency in magnesium can be corrected rapidly with Epsom salts (also known as magnesium sulfate), which can be found in pharmacies and online.

Make a spray bottle full of Epsom salts and water with about a teaspoon per liter (quarter gallon). Use a fine spray setting to water the foliage every two weeks on your tomato plants. The leaves will absorb it quickly. Spraying should be avoided on hot, sunny days or when rain is expected, and avoid overdosing.

The more nutrients a plant has, the harder it is for it to take up others, resulting in further problems. Using a liquid seaweed feed or tomato fertilizer containing seaweed alternates with the Epsom salt treatment.

You can boost your plants’ vigor by feeding them liquid seaweed, which contains a variety of nutrients. As an added bonus, this all-purpose plant tonic covers all your bases as a backup in case your diagnosis turns out to be wrong. Identifying nutrient deficiencies can be challenging!

Blistering type symptoms

Avoid tomato fertilizer for a few weeks if the problem is caused by the overuse of potassium fertilizers.

Should I Remove Yellow Leaves From Tomato Plant?

When your tomato plants grow to about 12 to 18 inches tall, you might notice that some of the leaves below the first set of flowers have turned yellow or died. Depending on the variety of tomatoes, you may remove the dead or yellow leaves as long as they are below the first set of flowers.

There is no benefit to removing dead or yellowing leaves, or suckers, that grow above the plant on determinate varieties of tomatoes. If the suckers grow higher than the first set of flowers on determinate tomatoes, you may choose to remove them.

It is important to remove dead or yellowing leaves at all heights from indeterminate tomato varieties and to prune them more generally than determinate varieties. It’s because determinate tomato plants set fruit once, so pruning can’t change how many tomatoes are produced. 

How Do You Fix Yellow Leaves On Plants?

Yellow leaves usually signal stress, and yellow leaves can’t turn green again once they’ve turned yellow. Watering and lighting are the most common causes, but fertilizer problems, pests, disease, acclimatization, temperature extremes, or transplant shock are also possible.

In general, once a leaf turns yellow, it’s gone. Occasionally a discolored leaf caused by poor nutrition or mild stress will green up again if the problem is addressed quickly, but don’t get your hopes up.

The plant, however, is not doomed. You can restore the plant to its former verdant glory if you address the yellow leaves.

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