Blossom End Rot: Why Tomatoes Get Black Bottoms
That dark, leathery patch on the bottom of tomatoes and peppers is a calcium problem, but it usually starts with watering.
What causes it
Blossom end rot happens when developing fruit cannot get enough calcium. Most garden soils contain plenty of calcium; the real issue is uneven watering, which stops the plant moving calcium into fast-growing fruit.
How to prevent it
Water deeply and regularly so the soil stays evenly moist, and mulch to slow evaporation. Avoid heavy doses of high-nitrogen fertiliser, which push leafy growth at the expense of fruit.
Quick tips
- Use drip irrigation if you can
- Mulch 2 to 3 inches deep
- Test soil pH every few years
What to do with affected fruit
Remove damaged fruit so the plant puts energy into new ones. Later fruit is usually fine once watering is steady. The unaffected part of the fruit is safe to eat.
