Pepper blossom-end rot: why the tip rots and what to do today

Your peppers set nicely, the fruits are growing – then a pale, watery patch appears at their tips, which within days sinks in, browns, and finally turns black. The sight is alarming, but the diagnosis is reassuring: this is not an infection but blossom-end rot – and if you act now, the next fruits will ripen intact.

What is happening at the tip of the fruit?

Blossom-end rot in peppers is the same physiological disorder as in tomatoes: not enough calcium reaches the tip of the fruit, so the cell walls being built there collapse and the tissue dies. That is why the spot always starts at the tip of the fruit – the point farthest from the water stream that transports calcium.

Since it is not caused by a pathogen, it does not spread from plant to plant, and it cannot be treated with fungicide sprays. The key to the solution is restoring the calcium supply.

Why are peppers more sensitive than tomatoes?

A pepper fruit grows quickly while its surface transpires very little – so the calcium-carrying water stream flows mainly toward the leaves, not into the fruit. In a heatwave this effect intensifies: the plant partially closes its stomata, transpiration drops, and calcium supply to the fruit practically stops. That is why the problem appears en masse during summer heatwaves – and why it often affects peppers and tomatoes at the same time.

Acidic soil, which keeps calcium bound, and uneven watering, which makes the water stream unpredictable, both make it worse.

What to do today

Remove the affected fruits – they will not recover. Set up an even watering rhythm: moderate watering daily or every other day in the early morning hours is better than one big soak per week. Mulch spread under the plants helps a lot in stabilizing soil moisture.

The fastest effect comes from calcium supplied through the foliage and fruit: the dissolved, immediately absorbable calcium of Genezis Kalcinol, applied as a spray, builds directly into the developing fruits. Repeated every 10–14 days, the next fruit sets will develop intact and spot-free. In a heatwave, always spray in the early morning and stick to the lower dose on the label.

Prevention for the rest of the season

The lasting solution stands on three legs: balanced soil pH (why is pH key?), balanced nutrition – for example with Garden Vegetable nutrient solution, which doesn't overdo nitrogen – and regular calcium supplementation. All three come together in the Blossom-End Rot Stop pack, which we put together specifically for tomatoes and peppers.

You can read in detail about the black spot appearing on tomatoes – and why it is not a disease – here.