There are a lot of questions and answers on this topic but I am not completely sure what the main issue is. There seems to be contradictory information as to what causes BER in tomatoes. I have two different tomato plans in the same bed (same soil but different variety) and one is getting BER and the other is not. Watering is is using drip irrigation. Here are some things I am doing and it would be great if someone can help identify the issue since most of the tomatoes in the impacted plant are getting BER.

  1. Bed prep - using a mix of steer manure (3 parts), chicken manure (1 part) and some compost

  2. Periodically and randomly water the plants in addition to drip.

  3. Fertilize using organic tomato fertilizer

  4. Growing zucchini, squash and eggplant in the same bed.

Some photos below to help identify the issue

  • 2
    Calcium deficiency. Use eggshells, gypsum. And tomatoes like Nitrogen. But your soil is all manure and compost, no coarse drainage like sand? Commented Jul 25, 2023 at 4:09
  • ïam sorry, Yosef, but your explanation is incorrect. Sure it is a calcium deficiency but in the fruit stalks and rarely the soil or roots. It is ultimately down to irregular watering that has compromised the transport systems from root to shoot, and, since Calcium is relatively insoluble in water, it is the first nutrient to become deprived when the xylem/phloem has been damaged (often irretrievably for that plant too sadly). Egg shells take centuries to break down and it is a myth that adding egg shells to the soil has any advantage whatsoever,
    – Nikki
    Commented Jul 25, 2023 at 18:43
  • Hi, photos are missing Commented Jul 26, 2023 at 12:46

1 Answer 1


Blossom-end rot of tomatoes is a physiological phenomenon that is characterized by a dry leathery area at the blossom end of the tomato fruit. This is associated with a localized deficiency of calcium at a critical stage in the very early development of the fruit. This deficiency has been associated with moisture stress and uneven watering.

It is the lack of calcium in the blossom end of the fruit at the time the fruit is set. Invariably it is not a deficiency of calcium in the soil but a result of under or overwatering in the soil. Calcium is not easily dissolved in water and so if the water and nutrient transport systems - Xylem & Phloem have been compromised due to poor watering, they will not function properly to get the calcium up the trunk BEFORE the fruit has set. Once the rot has started in a fruit it is best to remove it and throw it in the compost heap. It is not infected, just not got enough nutrients to make a perfect fruit and nothing you can do will fix it in that fruit.

Research shows that even a deficit of water for 30 minutes can impact the efficiency of the nutrient transport 'tubes' going up the stem. So, if you ever see one of your tomato or even pepper plants wilting, that is a sign that Blossom End Rot may follow.

Adding calcium in the form of directly absorbable chemicals e.g. gypsum might help but stuff like egg shells are useless since egg shells take centuries to break down and you need to deliver calcium quickly in a dissolvable form.

However, there might already be enough calcium in the soil and if you add more of it could even cause more trouble for your plants. Adding Epsom Salts (100% Magnesium Sulphate does nothing for blossom end rot and even may slow down the uptake of the calcium, making it even more in short supply at the fruit end of the plant since magnesium is antagonistic to calcium and it may 'steal' calcium's 'place' in the root and shoot's transport system.

I hope this helps. The best thing you can do is ensure plants never wilt but never get overwatered or waterlogged since root rot will also damage the nutrient transport system.

The full scientific explanation is here and a detailed reading is recommended.

Blossom End Rot - Scientific Explanation

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