Blossom End Rot in Tomatoes by Richard Bailey, Wellington, Surrey

Most of us have had tomatoes suffering from blossom end rot at some time - the base of the fruit flattens, eventually becoming concave, and goes brown, remaining hard, despite the name "rot".

What is Blossom End Rot?

The condition is a physiological disorder, caused by an imbalance of potash and calcium in the compost, which most often develops if the compost is allowed to dry out while the fruits are swelling. It is more common, therefore, with container grown plants than with plants growing in the open garden or greenhouse borders. It is most common of all, however, when plants are grown in grow bags, where they have a small, shallow root run that dries out easily.