Causes Of Tomato End Rot

If you are noticing brown, grey or black spots of rot appearing on the end of your tomatoes, which grow and become leathery in texture, they are likely infected by tomato end rot, or Blossum End Rot – a common tomato disease. Fortunately you have one of the less virulent tomato diseases to deal with here as although you can’t save infected tomatoes, you can save the plant.

Calcium Deficiency

Tomatoes need a great deal of nutrients to grow healthily, one of which is calcium. And this particular disease is causes by a calcium deficiency. You can get many calcium-rich fertilizers to help with this, such as compost containing eggshells – a very rich source of calcium.

You may well have enough calcium in your soil already, if it is rich with compost, and mulched well too. In this case Tomato Blossum End Rot might be due to inadequate water-flow and drainage in your soil, if the soil is too hard after a recent freeze for example. Make sure you water your plants well during periods of low precipitation and keep the soil moist with high amounts of organic matter and compost.

Some Recommended Steps

Here are some further solid steps you can take to deal with end rot in your tomatoes, as recommended by the NC Horticulture department:

  1. Add lime to the soil, working 2 cups of lime into the soil around each plant – digging up to 12 inches deep to reach all the roots.
  2. Do not apply too much fertilizer in one go, as this can also lead to Blossum End Rot.
  3. To retain moisture in the soil, mulch properly. The best way to mulch your plants is with decomposed saw dust, pine straw and normal straw, decomposed corn cobs and newspaper.

You don’t want too much change and fluctuation in the moisture of your soil. It’s best to try and keep it even. About 1.5 inches to 2 inches per week, through rainwater or your own watering. And an essential aspect to steady moisture levels and precipitation is good drainage. So before you plant your plants check the soil has good drainage by digging some holes and pouring water in to see how fast it disappears.

More Sources Of Calcium

The most direct way you can get calcium to your plants is with a direct spray of calcium solution. You can buy calcium nitrate of chloride at your local gardening store, and a good mix is 4 lb of calcium nitrate or calcium chloride per 100 gal of water. Apply this spray 2 or 3 times a week for best effect.

If your soil conditions are very acidic this reduces the calcium in the soil. The most common types of organic fertilizer you find at garden stores are bird-poo based fertilizers. This is because it is extremely cheap to produce and the profit margins are very high. But bird-based fertilizer is also very acidic – this can be a problem for your plants.

The very best fertilizer you can use for your tomato plants is cow manure-based fertilizer. It is incredibly rich in nutrients and the manure is mixed well with straw in the cow’s stomach, reducing the acidity. And an extra bonus is it’s usually cheaper too.


So to recap – you want to get rid of any tomato fruits showing signs of Blossum End Rot, then ensure the water levels and moisture is constant and even with good mulching and watering schedules. Also, feed your plant with more calcium via spray or compost with eggshells, and reduce the acidity of your soil by using cow fertilizer.

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