Southern Ontario, Canada. It has been crazy hot and humid - 33C plus humidity.
Do we need more water? Less? This is happening to about 1/3 of the tomatoes and they are not resting on the ground.
Edit: thanks everyone. She's going to start with a bit of lime and some more attention to how much she's watering.
She may even create a lemmy account now that she's seen how many helpful fellow gardeners around here, so win-win!
Thanks again
Blossom end rot caused by lack of uptake of calcium. This doesn’t necessarily mean you need to add more calcium to the soil though! It’s largely a watering issue. The plant is getting too much or not enough water and can’t make use of the calcium that may already be present in the soil. Tomatoes want about an inch of water a week and they are moody! Be consistent with your watering. Don’t over do it. Tomatoes will let you know when they feel neglected. There is a product called Rot Stop that is a calcium spray. Apply directly to the plant so it can uptake the calcium it’s not getting naturally.