How To Avoid Blossom End Rot
Blossom End Rot (BER) is a condition caused by a lack of calcium.
Calcium is used to build the fleshy wall – just inside the skin of a tomato – and when the calcium runs out, a black mark appears on the underside of a tomato leaving the fruit uneatable.
I once grew a plant called yellow pear where almost every tomato was affected by BER!
If you are growing tomatoes in containers, especially pots, it is extremely difficult to avoid BER because in order to do so, soil has to be kept constantly moist in order that plant roots have full access to the nutrients in the soil.
Dry soil means that no nutrients are available because roots can only access nutrients with moisture/water.
In hot weather it is impossible to keep soil “just moist”, so to avoid BER other methods can be used.
Foliar feeding with calcium is one of the best ways to add calcium into a plant because it is quickly absorbed.
Some minerals travel around a plant to the point of need more quickly than others. Unfortunately, calcium is a “slow mover” so feeding by roots takes time to reach the spot.
However, if calcium is applied regularly to roots (in small amounts) it can help greatly to avoid BER.
Not all tomato food contains calcium.
I recommend Chempak Calcium to be given as a root feed and foliar spray along with the addition of magnesium on a weekly basis from flowering.
Over-feeding before flowering can delay the production of flowers and fruit.