Blossom End Rot in Tomatoes and Peppers: Causes and Prevention

Q: What causes young tomatoes to get a black bottom that turns to rot?

Blossom end rot is caused by lack of calcium in the sap when small fruit is growing. Calcium moves to fruit via sap, but if roots dry out, calcium doesn't reach the fruit.

Applying calcium (lime) to soil doesn't help much. Foliar calcium sprays don't work because calcium can't move into sap that way.

The real cause is inconsistent watering, and perhaps over-fertilizing. Mulch plants and keep soil moist but not soggy to prevent blossom end rot.

Blossom End Rot Myths