Posted: 04/08/2013 at 23:25
The cause of blossom end rot is a lack of calcium, that however is most often caused by poor water transport through the plant, stopping shy of the end of the fruit and is fairly common.
Most nutrients are salts, especially nitrogenous ones, if these are applied too often and especially to dry soil then it draws the moisture out of the roots and therefore stops the plant moving it around. the best thing you can do is water if the plant is dry and water thoroughly.
Just remember, to make things harder if you over water you cause splitting and tastelessness in the fruits so don’t water if it isn’t needed.