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The Causes & Cures of Yellow Leaves on Tomato Plants

Updated on May 18, 2017
lobobrandon profile image

From his early days, Brandon helped his grandmother in her garden. He was always passionate about tomatoes.

Sometimes, the yellowing of tomato leaves is natural and not a cause of worry. On the other hand, sometimes you need to pay attention, because it could indicate something as silly as excess water to essential nutrient deficiencies, both of which are easy to fix once detected. Plus, if your tomato plants are under a pest attack, it could turn ugly.

It's not just a deficiency of nutrients that can cause foliage to lose color and deform, but also an excess of certain nutrients which leads to something gardeners refer to as a 'burn' which manifests as deformed, yellowish leaves and fruit.

If it's your first time growing tomatoes, mysterious problems can be detrimental to your confidence and many people give up after their first crop fails. Don't quit! Determine the problem and learn how to fix it so that your next crop grows well. Growing tomatoes or any other plant to perfection is a matter of skill, and all skills need to be developed.

It's not just the leaves that turn yellow due to deficiencies, you'll notice that the tomatoes are yellowish, too.
It's not just the leaves that turn yellow due to deficiencies, you'll notice that the tomatoes are yellowish, too.

Causes for Yellow Leaves on Tomato Plants

  • Excess Moisture. Tomato plants need perfect soil moisture levels. The soil shouldn’t be too damp nor too dry—always maintain the Goldilocks level. Water your crop based on your weather conditions, the soil type, and the level of mulch you use. In some places, you're going to need to water multiple times a day, whereas there are places where watering just a few times a week is best. For more on perfect watering techniques, I suggest checking out my article on watering tomato plants.
  • Soil Texture. The first time I planted tomatoes, I planted seeds directly into the garden, skipping the nursery stage. This resulted in the plants turning yellow when they were around a foot tall. After some research, I found out that the soil wasn't aerated well enough and it was too compact. The plants recovered after I dug up and loosed the soil a bit, which gave them enough room to spread their roots and breathe.
  • Viral, Fungal, or Bacterial Attacks. If you notice just a few plants exhibiting this problem, it's best to uproot and burn them since these pathogens are likely to spread to the neighboring plants that are doing well. If you want to find out a way to treat these issues, you're going to need professional help—your garden center may be able to guide you on this.
  • Pests. Pests can be controlled using predators or other natural methods. Pests are not always detectable—you may need to look closely at the stem or turn over the leaves to find them. I've seen white insects (research tells me they are mealybugs) and aphids. Soapy spray gets rid of mealybugs and ladybugs feast on aphids. You may want to search for natural ways to get rid of mealybugs if you're going the organic route.
  • Nutrient Deficiencies. Macro and micro-nutrient deficiencies are a leading cause of yellow leaves in plants, not just tomato plants. It does not necessarily mean that your soil is lacking—there are instances where the plant is simply incapable of absorbing nutrients. See below for more information.

These yellow streaks on a tomato indicate low nitrogen in the soil.
These yellow streaks on a tomato indicate low nitrogen in the soil.

Yellow Tomato Leaves Sometimes Indicate Nutrition Deficiency

  • Absorption Difficulty: Tomato plants can absorb nutrients only through their roots. If this is prevented for any reason, then they are going to lack key nutrients. Water is the medium through which they absorb nutrients from the soil. Therefore, you need to ensure they get sufficient water, but not too much (problems related to excess water have already been discussed).
  • Imbalanced Alkalinity. Is your soil pH acidic or alkaline? Tomato plants need the right pH range for successful absorption of nutrients. You’ll need to add a little fertilizer, but don’t over-fertilize, which leads to high pH.
  • Lack of Nitrogen: Due to a deficiency of nitrogen, the older leaves at the bottom usually turn yellow whereas the upper, new leaves remain bright green, as though there’s no problem at all. However, you’ll notice that the overall growth rate drops and your tomato plants will be shunted. You could add urea or ammonium to the soil or any other form of manure.
  • Deficiency of Potassium: Here, the leaf as a whole doesn’t turn yellow, but the area between veins turns yellowish and the leaves may wilt. You could add potash to your soil.
  • Calcium Deficiency: The growing tips of the plant may turn yellow and die within a few days. This is known as blossom end rot. Adding any compound containing calcium will work wonders.
  • Lack of Magnesium: This will result in stunted growth and the outer edges of the leaves may become pale and yellow. Epson salts are a good source of magnesium for your soil.
  • Sulphur Deficiency: Do the new leaves look yellow but the older foliage remains fresh and green? Does the plant suffers from stunted growth? Add sulphur.
  • Zinc Deficiency: Lack of zinc leads to the area between veins turning yellow, especially in the new leaves. This often leads to a bunch of small leaves at the top (a rosette).

All of these issues can easily be prevented if you amend the soil.

Learning From Other Gardeners Out There

Yellow Leaves on Tomato Plants – Not Always a Cause of Worry

If you observe any plant, eventually all the older leaves wilt and die. Similarly, your tomato plant will also have yellow leaves at the bottom. This is a normal stage of the growth cycle. Also it could indicate a lack of sunshine due to shading by the higher leaves. As long as the plant continues to grow healthily and produce fruits, you need not worry.

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    • stephaniedas profile image

      Stephanie Das 5 years ago from Miami, US

      Do you think that these tips apply to a lot of other plants, too? I had problems with my basil turning yellow this summer.

    • lobobrandon profile image
      Author

      Brandon Lobo 5 years ago

      Yes the same tips apply to others as well. I don't know about the extra water but the nutrient deficiencies etc. applies to all plants.

    • WD Curry 111 profile image

      WD Curry 111 5 years ago from Space Coast

      I checked funny, too. I laughed at my ignorance. I was surprised that people garden tomatoes in India. I should have known from all of the wonderful sauces in your sophisticated menu. If you want to flirt with disaster, grow tomatoes in this part of Florida (nematodes). Sometimes we actually get a crop. It is usually the fall planting that rewards you, but we try in spring anyway. This will surely help.

      You are very professional in your presentation and practical application of opportunities. There is hope for the future with young men like you leading the way.

    • lobobrandon profile image
      Author

      Brandon Lobo 5 years ago

      Hi WD Curry thanks for the great comment. Nice and motivating :)

      Great that you found my style of writing pleasant and useful. I'm just 18 and looking forward to writing lots and lots here on hub pages.

    • WD Curry 111 profile image

      WD Curry 111 5 years ago from Space Coast

      I'll be looking forward to reading more of your work and applauding your success.

    • WD Curry 111 profile image

      WD Curry 111 5 years ago from Space Coast

      Can you hear me clapping my hands and jumping up and down?

      Here is a proverb that applies to you. "Do you see a man who is skilled and diligent in his work? He will stand before kings, and not before obscure men." Go get em' Tiger.

    • Madurai profile image

      Madurai 5 years ago from Online

      usually a plant turns yellow due to a lack of nitrogen in the soil. You have provided here great info about the symptoms of yellow leaves. Thanks for sharing..

    • lobobrandon profile image
      Author

      Brandon Lobo 5 years ago

      Thanks Madurai for adding this info to the hub. Yes, Nitrogen could be just one of the many causes and you'd need to check all possibilities when determining the cause because, you wouldn't know if the yellow leaves were caused due to an infection or pest.

    • profile image

      help me 5 years ago

      My tomato plants turned all yellow I think because of too much sun and white flies. I trimmed all the leaves off, so will the plant survive? I have one that all it has on it now are two tomatoes, no leaves. Will the leaves grow back or is this plant a looser?

    • lobobrandon profile image
      Author

      Brandon Lobo 5 years ago

      Too much sun won't be the cause of yellow tomato leaves. However, the white flies could potentially be a cause. Are your plants receiving enough water? Do you add fertilizers? I've written articles about these steps too. You'd find links to them on this article itself.

      Yes, your tomato plant stands a chance; but, the chances are slim; make sure to take care of it until it recovers and gets new leaves. If you think the sun is an issue try using a sort of shelter over the plant - at least till it recovers.

    • profile image

      Sharon 2 years ago

      Epson salt, too much,killed most of the new tomato plants. Hubby put 2heaping tablespoons per plant when planting! Had to re-plant nearly all the plants as they just died. Do not recommend epson salts???

    • lobobrandon profile image
      Author

      Brandon Lobo 2 years ago

      Hi Sharon, I've never tried epson salts as I use organic compost made at home itself. Why don't you try it out (in a smaller amount) on 2 - 3 tomato plants and check out the progress in their growth

    • profile image

      Laura 9 months ago

      You do best by adding epson in watering .

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