What is Blossom End Rot and How Can you Fix it?

Blossom end rot is a common garden problem. It is often caused by a lack of calcium and/or uneven watering. 

As a serious disorder of many tomato, pepper, cucumber and eggplant plants, blossom end rot is caused by environmental reasons. It is not a fungal rot as many presume it to be.

Please read: This information is provided for educational purposes only and is not intended to treat, diagnose or prevent any disease. We encourage you to make your own health care decisions in partnership with a qualified health care professional.

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Blossom end rot is most often caused by uneven watering or by a calcium deficiency in the plant, not necessarily a deficiency in the soil!


Uneven watering can interfere with the uptake of calcium, as can an imbalance of the soils pH.

This common garden “disease” is often brought on by rapid growth from too much fertilizer at once, high salt levels in the soil or drought/poor watering in a tunnel house/green house.

Blossom end rot

Symptoms of Blossom End Rot

Blossom end rot symptoms occur on both green and ripe fruits and is identified by areas that gradually widen and mature into sunken, brown/black, leathery spots on the bottom end of the fruits.

Often you will get a “secondary infection” which may appear as a black, fuzzy-like growth, attack the affected area and cause complete rotting of the fruit.

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Blossom end rot is not contagious, and will not spread from plant to plant.

How to Treat Blossom End Rot

Since this plant problem is environmental in nature, fungicides will not work on it.

To treat or prevent blossom end rot try the following:

  • Choose resistant vegetable varieties whenever possible
  • Keep the soil evenly moist
  • Foliar (leaf) spray plants with a kelp or calcium solution
  • Add higher levels of calcium to the soil by adding bone meal, oyster shell or gypsum to the soil at planting time
  • A thick layer of mulch will help conserve soil moisture to keep the soil more evenly moist
  • Avoid using high nitrogen fertilizers which speed up and encourage leafy growth and reduce the uptake of calcium by plants.

Blossom end rot does not herald the end of your cropping and harvesting! It is a simple problem to treat, and once you have added more calcium and moistened the soil, your plants will continue to thrive and produce.

Because the “rot” is not actually a rot, the fruit above the discoloration is still safe to eat. Simply cut the darkened end off of the fruit, plus a little bit extra and throw it away.

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