What is BLOSSOM END ROT? How to identify and prevent it?


Blossom end rot is a biochemical problem that affects tomatoes and many other plants. Blossom end rot (BER) is a very common and serious problem in tomato plants. It can also happen to peppers, eggplant, zucchini, and tomatoes. No common plant bug or disease is to blame.

tomatoes having blossom end rots, the black bottom.

Damage from tomato blossom end rot is easy to spot because it usually shows up when plants are about halfway through their growth. At the bottom of the tomato, brown, water-soaked, sunken spots form and grow until they cover about one-third to one-half of the whole tomato.

After a while, these weak spots start to harden, turning dark and looking tough and rubbery. The top of the tomato will look just like it does now, and it will still be attached to the plant. The bottom, however, will be very different.

How to identify blossom end rot in tomatoes?

identifying blossom end rots in tomato plants

Blossom end rot shows up as flat, dry, sunken, dark tissue at the blossom end of the tomato, which is the opposite of the stalk end.

On the roots of tomatoes that are still growing, rust starts as a small, wet spot that gets bigger as the tomato grows. The size of the rotten area varies, but it can cover anywhere from 30% to 50% of the tomato.

Sunscald, which looks like a white rash, is often mistaken for it because the affected area on peppers is brown. Secondary fungi that cover the affected areas often spread to the leftover food, making it useless.

This is not a bug or sickness, but a biological problem caused by a lack of calcium in the tomato as it grows.

What are the causes of Blossom End Rot in tomato plants?

causes of blossom end rot in tomato plants

Even though some people think blossom end rot is a disease because it makes the tomato look bad, it is not caused by any bacteria found in plants. The problem is mostly caused by a lack of calcium, which comes from food.

Tomatoes need many different minerals to grow and stay healthy. Nitrogen, phosphate, and potassium are the three most important ones. (called macronutrients). But plants also need several secondary and micronutrients to stay healthy overall.

Calcium is one of the most important chemicals that help the body work. During the growing season, tomato plants need a lot of calcium to make food.

When plants don’t have enough of this important nutrient, it makes it hard for them to do their jobs, which leads to rotting spots at the roots.

From a scientific point of view, this lack has to do with how cells work. A lack of calcium causes the cell wall of the tomato plant, which covers all the important parts inside the cell, to grow. This growth hurts the cells and, in the long run, the tissues at the base of the tomato.

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The main reason for blossom end rot

blossom end rots because of deficiency of calcium.

When gardeners hear that there isn’t enough calcium in the soil, they might think that blossom end rot is just a problem with the soil and use fertilizer to fix it.

Even though it could happen, this is not the most common reason. Most soils already have enough calcium to keep tomato plants alive without adding more.

Plants need water to get the nutrients they need. When crops don’t get water for a while or aren’t watered regularly throughout the season, calcium can’t get to where it’s needed, which can cause them to rot.

Other reasons for blossom end rot in tomato plants

tomatoes with rotten ends

There are several other reasons why your tomatoes aren’t taking up the calcium in the soil:

  • Misusing fertilizer: When some minerals are out of balance, like when there is too much nitrogen or magnesium, tomato plants can’t get enough calcium.
  • Temperatures below freezing: Tomatoes like it when it’s not too cold, and they take in less food in the winter.
  • Not enough pH in the soil: The pH of the soil affects how well calcium is taken.
  • Too many ions: Using too much fertilizer or washing plants with bad water builds up salts in the soil, which hurts the roots and makes it harder for the plants to take in nutrients.
  • Competition: If tomatoes are too close to each other or near other goods of the same kind, they will use up water and minerals much more quickly and become lacking.
  • Damaged roots: Damage to the plant’s large root system from farming tools or cutting nearby plants will make it harder for the plant to absorb calcium.

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Blossom End Rot: 4 Ways to prevent It in tomato plants

Blossom end rot is a good thing because it won’t kill your much-anticipated tomato crop. Since it’s not contagious, a tomato with symptoms won’t “tell” a friend about their problem.

There is no good way to handle pharmaceuticals, like pesticides. Simply put, this type of tomato rot is a problem that usually goes away when the soil around your plants stays moist.

Blossom end rot can be stopped by following these four tips.

1. Tomato plants should always have enough water

water tomatoes daily to protect them from blossom end rots.

About an inch of rain or watering per week is the best amount of water for tomatoes to grow. When rainwater isn’t enough, you can water your plants with a soaking line or a watering can.

This is very important if you want to grow tomatoes in pots because they dry out faster.

Garden Tip: When you water, don’t let the plants get too wet to stop the spread of leaf diseases. Yes, the rain will make your plants wet, which makes it easier for diseases to spread. Keep plants’ leaves as fresh as possible.

2. Use wood chips as mulch around tomato plants

use wood chips for mulching in the soil.

Put a 2-inch layer of organic fertilizer around the base of your plants. Straw, grass clippings, cut leaves, or ground-up bark are all good choices.

Mulch helps keep water in the soil, so your plants won’t dry out as fast when it doesn’t rain or you don’t water them. It also helps cover up plants.

3. Avoid overfertilizing

do not add to much fertilizers in the tomato plants

When plants get too much dung, they may grow faster than they can take in the calcium they need for healthy growth. Rapid growth can cause the blossom end to rot.

The best way to add nutrition to the soil is to cover it with a layer of well-rotted dung that is 2 inches thick before planting in the spring. Minerals will be slowly released, and the structure of the soil will be improved as well.

A soil test should be done to see if fertilizer is needed, and the directions on the package should be followed to the letter.

4. Take care of the roots

take care of roots of tomatoes plants

blossom end rot can be stopped by making sure the roots take in calcium. Avoid disturbing the bottom zone of a tomato plant so that it can get the most calcium. Don’t hoe or dig around a plant’s roots. Instead, use fertilizer to keep plants in check.


Blossom end rot is annoying, but it’s not the end of the world either. With a few changes, your later tomatoes should be as round and juicy as you expected. If the color doesn’t bother you, you can always cut off the colored parts of the veggies and still eat the rest.

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