Yellow Leaves on Tomato Plants: Causes & Treatments

Many people wonder how to solve the issue of yellow leaves on tomato plants. It is indeed very complicated because there are several types of problems that cause yellow leaves.

Here is a description of the most common problems with yellow leaves on tomato plants and their solution.

Yellow Leaves on Tomato Plants

Excess Water

Symptoms: The leaves look yellow and pale, apart from the fact that you know perfectly well how often you water your tomato plants. Excess water causes the roots to rot (little by little) and can also cause fungus.

Solution: If you have a pot and you can put drainage without suffering much the plant, well, if not you already know for the next time. If it is a pot or container, check that it has holes in the bottom and raise the container a few inches off the ground, so the water will be eliminated little by little. You can also add sand to the substrate to absorb excess water.

Lack of Water

Now let’s go to the opposite of the above.

Symptom: The leaves dry out and some of them are crunchy.

Solution: Water with more water and more regularly, remember that the water must penetrate to the root so that it can be absorbed. Also, try to avoid the hottest hours of the day, you may water correctly, but most of it will evaporate.

Lack of Light

How I detect it: The leaves look discolored and decayed. Keep in mind that the ideal is 5 hours of sun, so that the tomatoes evolve correctly, although with some less they also develop.

Solution: Change the location of your plants. If they are planted in the ground, and already have a flower, forget you should not repot it because surely, you will ruin the fruit and it is not worth it, try to pamper them so that they evolve and give fruit in the place you have them and for the next plantation you already know to write it down.

yellow leaves on tomato plants lack sun

Leaf-eating Insects

How you detect: Usually under the leaves, there are small insects that devour the leaves or suck the sap leaving it yellow until it becomes transparent.

How you can solve it: Use an ecological insecticide such as Neem oil or you can apply potassium soap.

Yellow Leaves on Tomato Plants: Lack of Nutrients

Nutrients are very necessary and in many cases, you will have to incorporate them. This happens a lot when you grow in containers such as grow tables or pots and the plant consumes the nutrients before the fruit ripening cycle is finished.

tomato plant lack of nutrients

1.- Lack of Potassium

Symptoms: Edges and tips are yellow.

Solution: Add organic compost or vermicompost. If the compost is homemade, you will have incorporated fruit and vegetable scraps, which will add the necessary potassium to your tomato plants.

2.- Nitrogen

Symptoms: Yellow edges, tips, and veins of leaves.

Solution: Add organic compost, manure, or coffee grounds, which are rich in nitrogen.

3.- Lack of Calcium

Symptoms: Leaves become deformed and yellow.

Solution: First check the acidity of the soil in which the plants are planted. To fix it, if the soil is very alkaline, incorporate gypsum, if the soil is very acid, incorporate lime. This should ideally be done before planting.

4.- Lack of Iron

Symptoms: very yellow leaves and veins with small green streaks, especially on new leaves.

Solution: Add nettle slurry or worm castings, this is enough.

5.- Lack of Magnesium in the Orchard

Symptoms: Pale color on the whole leaf including veins.

Solution: Add nettle slurry or worm castings, as with iron deficiency.

6.- Zinc

Symptoms: Leaves show discoloration between leaf veins.

Solution: Spray seaweed extract on leaves (or other organic foliar fertilizer containing zinc).

Conclusions About Yellow Leaves on Tomato Plants

The subject of treatment of pests or problems in the plants is very focused on the experience, all this that I have related to you, once you have an experience of cultivation of several seasons, you will detect the problem at a glance, without the need for consultation. I hope this guide about yellow leaves on tomato plants will be of great help to you.

yellow leaf tomato
About Henry Morgan

We are the Morgan family, Henry, and Morgan, both agronomists from the University of Michigan, where we met. We are experts in putting our hands in the soil and developing organic foods and improving production processes for decades. Likewise, we have worked for companies such as Mondelez International, BASF, Monsanto, etc. currently in our role as science writers for as well as advisors in promoting large scale food growing in urbanized areas. In this website, we share what we are most passionate about, gardening and farming. Enjoy and see real photos on our website.