My tomato plants look beautiful. However, most of the tomatoes, when they start to turn red, they also start to spoil and turn black from the bottom up. Why is that? Could it be bugs or too much water?
Your tomatoes have Blossom End Rot. It can be caused by inconsistent watering and/or a calcium deficiency. We have lots of calcium in our soil, so I bet it's your watering..
The tomatoes like to be watered down 18" every 5 days (your other vegetables can be watered down to a depth of 12" one time a week). Throw away the affected tomatoes because they usually taste terrible. If you water correctly, the new tomatoes should taste wonderful.
Posted on 15 Aug 2007
Horticulture Assistant, Utah County