Growing Tomatoes in Containers
Blossom End Rot (BER) is not a disease, it's a physiological condition of tomatoes. It usually occurs after a heat wave early in the summer, and arises when the plant's growth outstrips its ability to deliver water all the way to the tip of the fruit. It usually only affects the tomato trusses that are growing rapidly at the time.
Irregular or inadequate water is the most common cause, and over-fertilization can contribute. Inadequate calcium was once thought to be the culprit, but only in rare cases is calcium deficiency the cause. BER is common in container-grown tomatoes.
Affected tomatoes are still edible, just cut off the bad part of the fruit. With adequate water, the problem usually self-corrects, but if you want to avoid it entirely, grow cherry tomatoes. Photo by Steve Masley