How to treat blossom end rot in tomatoes (black rot at the base of the fruit)

The black rotting at the base of tomato fruits is a disease called blossom-end rot. The disease is called blossom-end rot because it affects the base of the fruit where the blossom or flower used to be. The flower is attached to the bottom of the fruit until it falls off.

Treating blossom end rot treatment in tomatoes

I recommend using any of these two methods because they worked for me. You can use just one or both and see using the direction on the labels to get the best results.

Applying fertilizers to the soil

To increase the calcium in the soil, you can add fertilizers like CAN which contains calcium. Once added to the soil during top dressing, you irrigate with a lot of water to make sure the fertilizer dissolves and is available to plants for absorption.

Whether you are using a drip irrigation system or a furrow irrigation system, ensure that you supply enough water to the soil to dissolve the fertilizer. The fertilizer will dissolve slowly and will be absorbed by the tomato plant.

Applying blossom end rot spray on the leaves

Another way to get rid of the blossom-end rot problem is to use foliar fertilizers. Foliar means on the leaf. Therefore, foliar fertilizers are fertilizers that are applied directly to the leaves of tomatoes. In the case of blossom-end rot, you use a foliar fertilizer that has a lot of calcium.

Depending on the manufacturer, they go by different names and come in different forms. Some are crystals that you dissolve in water while some are in liquid form. The fertilizer is dissolved in water inside a knapsack sprayer.

The sprayer is the same one you use for spraying pesticides. The amount to use is written on the package. Be sure to follow the instructions on the packaging to get the best results.

If it rains after you spray, the fertilizer may have been washed away from the leaves so you need to repeat the process.

Irrigating with sufficient amounts of water

Tomatoes need wet soil so that they can absorb nutrients. The moisture helps them dissolve and absorb the nutrients. Every time you water, check to see how deep the water sink using a pipe or a stick.

Watering a newly planted seedbed with a watering can – close up view of the nozzle and spray of water over the soil

The soil should be moist to not less than six inches deep. This is adequate for the tomato plants.

I should tell you that the condition is irreversible for the fruits have advanced blossom—end rot. Those showing early signs of the disease will recover partially. What I mean here is that you will be able to sell them but they will not look as healthy as the grade 1 tomatoes.

How can you identify tomato plant blossom end rot?

The blossom-end rot is a nutrient deficiency disease in tomatoes. Plants need various nutrients to grow to maturity and produce a good harvest. They get these nutrients from the soil and environment during feeding.

Nutrient deficiency diseases occur when your plant does not receive adequate amounts of nutrients. Blossom-end rot occurs when the tomato fruit lacks enough calcium minerals in its system.  You can go to sleep with healthy plants and wake up the next morning to dead plants.

What causes blossom end rot in tomatoes?

The lack of calcium in the plant can be brought about by two things:

Lack of adequate calcium supply for the plant to absorb

Low calcium supply can be caused by intensive farming rotations in one place. Especially when working with fruits that require a lot of calcium. Such practices use up all the nutrients in the soil. You should perform a soil test to give you information on which nutrients may be lacking in your soil before you begin planting.

When you come to plant a new crop, the crop will have some calcium deficiencies. When the calcium gets into the plant, healthy fruits will be formed and you will no longer have a blossom-end rot problem.

Read More: Soil and water test for tomatoes, what you should know!

Lack of sufficient water supply in the soil to absorb the calcium from the soil

Another cause of blossom-end rot is a lack of adequate water supply. When the water supply is low in the soil and plant, the plant cannot absorb calcium and transport it to the fruits causing blossom-end rot.

If you practice good farming practices or have applied fertilizer, all you have to do is improve your irrigation regimen or the intervals of irrigation on your tomatoes. The water will dissolve the fertilizer and make it available to the plant. You will see a change in the next fruits to mature.

Taking care of these two issues will get rid of the problem very quickly. The fruits that are yet to be formed will grow to maturity and be very healthy.

Make sure you keep up the practice to maintain a good balance of calcium in the plant. You will no longer have to worry about your fruits getting blossom-end rot till the end of the harvest period.

Read More: Irrigation Practices

Keep an eye out for any blossom end rot symptoms…

Watch out for signs of disease like a change in color of the leaves or spots on the leaves or fruits. If you spot anything out of the ordinary, you can search for those symptoms on the internet or call a crop doctor to advise you on the way forward.

They might have to visit your farm to find out exactly what it is you were describing or you can send them a photo on WhatsApp or email.


Tomatoes are a very profitable fruit to grow. They are a common part of many dishes and most households have a budget for tomatoes on a weekly basis.

With a growing global population, the market for tomatoes is growing with it. They are also affected by many diseases which can destroy your crop in a short time.

Make it a habit to walk around the farm and look at the plants and the fruits.

You cannot go wrong if you keep up with these good farming practices. All the best!

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