I have several plants in my garden...but I had a few plants left over and dropped them in a large container. the container garden had 6 tomatoes on it. One was nice and red , not real big....but big enough that I couldn't wait...I picked it today....and the bottom was missing and all black.
I've noticed this happens when we have a dry spell followed by rain. I agree that the mulch helps considerably with this. Maybe it is a soil borne organism like Baumer suggests, I never thought of that...I thought the mulch was helping conserve moisture.
It can also be caused by uneven watering of the plant, and is sometimes a problem in container grown plants, but it is more common on the first tomatoes the plant produces, the later ones should be ok unless there is a real calcium deficiency or water problem.
The CAUSE of Blossom End Rot is calcium deficiency....but that deficiency is most often caused by insufficient water or fluctuations in soil moisture. Potted tomatoes are very suceptable. Linda C
