Contains two important nutrients that plants need Calcium (Ca) and Nitrogen (N). Hi-Yield Calcium Nitrate is used primarily in vegetable gardens, particularly for tomatoes and peppers, in the prevention of blossom end rot. Blossom end rot is a common problem with tomatoes. It is a physiological disorder (not a disease) caused by a lack of calcium. When fruits are enlarging rapidly, sufficient amounts of calcium fail to reach the end of the fruit resulting in a deficiency of calcium in the developing fruit.