Blossom End Rot

Lycopersicon esculentum

Also known as ‘blackheart’, blossom end rot (BER) appears on an array of edibles – including tomatoes, lemons, peppers, apples, eggplants and even watermelons.

The ends of the affected fruit present as a sunken, leathery, blackened scar that rots the fruit, damaging the core. In bad cases the fruit becomes inedible. While it most commonly appears on the first fruit of the season, it can happen all year round.

BER is usually due to a lack of calcium, along with irregular watering. The rot is caused by the cells on the blossom end of the fruit dying and disturbing the natural growth process.


Make sure your tomato plants are well watered. If they are grown in the ground, they will need watering at least twice a week (possibly more, depending on the soil). Plants in pots may need watering every day over summer.

Always water your tomato plants around the roots and add mulch to avoid fluctuating soil temperatures. Feed them regularly with Kings Tomato food to ensure each plant has the nutrients it needs for optimal health.

Citrus and other fruit
BER can also occur in other fruit, though usually only the first crop of the season is affected. To avoid BER in fruit, feed plants well with high quality liquid fertiliser such as Kings citrus and fruit tree fertiliser.


To treat BER,  switch to a fertiliser low in phosphorus and nitrogen, and  start feeding with a product high in magnesium and calcium. Liquid Magnesium Chelate (for lemons) and Kings Garden Lime are all high quality products that will provide the support your plants need.

Remove any affected fruit to encourage new fruit production.

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