Blossom end rot - usually from over watering.

BER is caused by a calcium deficiency, usually induced by fluctuations in a plant’s water supply. Because calcium is not a “mobile” element in plants, even brief changes in the water supply can cause BER.

Droughty soil or damage to the roots from excessive or improper cultivation (severe root pruning) can restrict water intake, thus preventing plants from getting the calcium they need. Plants also can develop calcium deficiency and BER if they are growing in highly acidic soil or are getting too much water from heavy rain, overirrigation, or high relative humidity.

One possible solution to calcium deficiency: Pulverize egg shells and work into the soil around the plants.

blossom end rot

OP, what is your watering schedule, and do you mulch? This will probably be the larger cause of your blossom end rot. Yes, you can try and save as many untouched tomatoes immediately by adding a tomato specific fertiliser or calcium, but your real issue is probably watering.

OP, what is your watering schedule, and do you mulch? This will probably be the larger cause of your blossom end rot. Yes, you can try and save as many untouched tomatoes immediately by adding a tomato specific fertiliser or calcium, but your real issue is probably watering.

Eggshells take too long to dissolve, even when powdered, to fix this issue quickly. Grab some bonide rot stop or fertilome yield booster which are liquid formulas you can dilute and add to stop end rot. I had this issue with certain varieties of tomato when grown in pots, and I discovered that watering once a day was not enough, and the tomatoes depleted all the nutrition in the soil pretty quickly. I mulch and then water twice a day when it gets above 90f, and add yield booster every few weeks.

OP, what is your watering schedule, and do you mulch? This will probably be the larger cause of your blossom end rot. Yes, you can try and save as many untouched tomatoes immediately by adding a tomato specific fertiliser or calcium, but your real issue is probably watering.

OP, what is your watering schedule, and do you mulch? This will probably be the larger cause of your blossom end rot. Yes, you can try and save as many untouched tomatoes immediately by adding a tomato specific fertiliser or calcium, but your real issue is probably watering.