Question: My tomatoes have a big rotten spot on the bottom that is ruining all of them. The rest of the plant looks healthy. How do I stop this disease? I'm so upset.
Answer: We're getting lots of calls about blossom end rot. It is not a disease or insect. It is the deficiency of a nutrient, namely calcium. Usually this means 1) you have too little calcium in the soil or 2) the calcium is not moving through the plant (not enough water in the soil). Add calcium by working powdered lime (calcium carbonate) into the soil beneath your plants and watering it in. You can also spray a calcium product, such as Stop-Rot, on the leaves. Before the next growing season, do a soil test because your whole vegetable garden may need lime. Also, stir a handful of lime into each planting hole next spring. Irregular or insufficient watering can also lead to blossom end rot. Be sure to water deeply and regularly. Pick off any tomatoes which show blossom end rot so your plants do not waste energy on them.