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Tomato Blossom End Rot: How to Treat and Prevent It

Do your tomatoes look like they have something similar to tooth decay? It’s probably because they do! Actually, not tooth decay but something called tomato blossom end rot, which is tissue decay.

Blossom end rot is a disorder that appears in vegetables and fruits. The outside of the fruit looks fine, but the inside gets discolored and shrunken. Blossom end rot happens because bacteria and fungi invade the discolored areas.

This condition may sound overwhelming, but don’t worry! In this article, we will learn what causes it and how we can prevent tissue decay from happening in your tomatoes!

An unripe tomato showing signs of tomato blossom end rot.
A textbook case of tomato blossom end rot.

Causes of Tomato Blossom End Rot

There is a misconception that tomato blossom end rot or bottom rot is caused by a disease, fungus, insect pest, or bacteria. This is incorrect! Blossom end rot is a physiological disorder thought to be caused by stress combined with a lack of calcium, brought on by dry conditions, in the developing fruit.

Calcium Deficiency

To maintain healthy growth, tomato plants require calcium throughout all parts, from the roots to their fruits. Calcium is transported from place to place by the water. When the soil is dry, and the water is insufficient, calcium cannot work its way through the roots of the developing tomatoes. This is causing tomato blossom end rot.

Note: If you’re having trouble getting your tomatoes to develop properly, it may mean there’s a lack of calcium in the soil. However, this is unusual since most soils have enough; typically, the problem is related to unreliable moisture levels. A soil test can confirm if you need more calcium or not.

First of the First!

A cluster of small tomatoes with blossom end rot.

Tomato blossom end rot usually affects the first tomatoes of a plant.

The season’s first tomatoes are most susceptible because all parts of the plant are rapidly growing, so calcium is in high demand. As the plant moves calcium up from its roots, stems, and leaves will use it up first, so occasionally, there won’t be enough left for the ripening fruit, resulting in tomato blossom end rot.

Other Causes

During the formation of the tomatoes, calcium deficiency can also be caused by:

  • Increased quantity of nitrogen-heavy fertilizer
  • Improper soil pH
  • Increased salt levels in the soil

Stopping Tomato Blossom End Rot

Small green tomatoes with signs of tomato blossom end rot.

Unfortunately, for the fruit showing signs of blossom end rot, the condition is irreversible. The only thing you can do is remove the affected tomatoes and try to balance the calcium levels of the plant. This will help the next round of tomatoes to grow healthy.

Note: Ensure the tomatoes with severe blossom end rot are picked and composted.

Preventing Tomato Blossom End Rot

The good news of the day: there are measures you can take with your tomato plants that make tomato blossom end rot preventable!


A drip irrigation line watering tomato plants.

The key to preventing it is to make sure that the soil is moistened. Another important thing is to make sure that the plant is watered regularly, especially in dry weather areas.

It’s best to water the roots deeply with one inch of water every week, applied in one go for a slow, steady soak. Overwatering your plants by adding too much water each day can make the issue worse because it doesn’t reach the roots properly.

Remember! Calcium in the soil needs to make its way to the roots of the plants, by entering through the soil moisture.

For optimal calcium absorption, the pH of your garden soil should be maintained at approximately 6.5. Plants can absorb calcium and other nutrients more easily when the pH level is balanced.


Mulching around tomato plants.

Mulching is the best way to help the soil to maintain its moisture. The plants won’t dry out between waterings or rains. It also helps smother weeds.

It’s important to mulch at the right time and in the correct way. To increase soil moisture levels, you can add a 2-3 inch layer of organic matter to the top of the soil, near your tomato plants, during the start of the season.

Uncut grass, leaves, and straw make excellent mulch for tomatoes.


Person spreading fertilizer around tomato plants.

Tomato plants supplied with ammonia-based nitrogen fertilizers cannot take up calcium due to the excessive ammonium ions blocking its absorption.

Suggested fertilizers to use for your tomatoes include organic granular fertilizer, fish or seaweed emulsion, or liquid kelp.

Ideally, to enrich the soil with nutrients, you will need to add a layer of compost that is decomposed well and is 2 inches thick right before planting in spring. Doing so will make the soil structure better while slowly releasing nutrients.

Please note: The instructions on the fertilizer label should be followed carefully, and only use when recommended by a soil test. It’s important you don’t overfertilize, especially with the synthetic chemical kind.


Maintaining healthy roots is vital, as they absorb the calcium needed to prevent blossom end rot.

Important note: Do not disturb the root zone of your tomato plant, so it can absorb the maximum amount of calcium.

Best Fertilizer for Tomato Blossom End Rot

Person adding fertilizer granules around a tomato plant.

The best tomato fertilizers for combating blossom end rot provide a fast-acting nitrogen source plus calcium for the best fruit and vegetable quality.

We highly recommend the calcium nitrate fertilizer carried by one of our favorite garden-supply retailers, Hoss Tools.

Ways to Remove Tomato Blossom End Rot Naturally

Person spreading crushed egg shells around a tomato plant.

There is a high possibility that you have heard of some calcium-boosting home remedies, such as planting your tomatoes with antacid tablets or egg shells in the holes to avoid blossom end rot.

If your tomatoes are infected, and you want to help them, naturally, try to remove all the affected tomatoes, and water with powdered milk, for some extra calcium. The next batch should look fine!


Is it safe to eat a tomato with blossom end rot?

A ripening tomato with blossom end rot.

Yes, you can cut away the rotted portion of your tomatoes and eat the rest. However, many people find that tomatoes affected with blossom end rot have a mealy texture and are less flavorful than healthy tomatoes.

If tomatoes have signs of blossom end rot, don’t try to can them or use any other preservation method; just eat them fresh.

Can tomato blossom end rot damage the entire plant?

Unripe pear tomatoes with blossom end rot developing.

Blossom end rot usually affects the fruit and not the entire plant. Even though the signs are only visible in the outside part of the fruit, blossom rot can be caused by issues that have to do with the plant’s roots.

If the root system has not matured adequately, it might not be able to obtain enough water and calcium from the soil, and this lack may result in blossom end rot appearing.

In other words, while the symptoms are observed on the fruit alone and where its effects are limited, root problems can bring about blossom end rot.

Wrapping up Blossom End Rot in Tomatoes

Small pear tomato with blossom end rot.

And that’s a wrap! We really hope that by reading this article, you’re less overwhelmed now that you know how to prevent your own tomatoes from getting blossom end rot.

The good news is that blossom end rot doesn’t mean the end of your tomato season if it does show up. The even better news is that it’s an easily treatable and preventable condition by taking a few simple measures.

Want to learn more about tomatoes? Visit the Tomato Plants page on our website and we’ll oblige you! We’ve got blog posts on more than 70 delicious varieties of tomatoes, helpful growing and care guides, and ideas for all sorts of tomato gardening techniques.