How to foil blossom end rot on tomatoes
You've waited all season for those garden tomatoes to ripen and then you see the bottom of the fruit is rotted. Nothing is more frustrating.
Dry summers are often accompanied by what's called blossom end rot on tomatoes. When the soil dries out, the plant can't uptake the calcium it needs, which causes a brown or black lesion to appear on the bottom of the fruit.
The good news is that often times it’s just certain varieties and the first tomatoes that are hit with the rot. Also, sometimes tomatoes can heal the bottom of the tomato and still be edible. Container plantings are especially at risk. That's why early in the season, I recommend a 15 gallon or bigger container. The bigger they are, the less they need watered. Self-watering containers like an Earth Box are great ways to grow tomatoes in containers. Self-watering containers have a reservoir below and as long as it's kept filled with water, the soil will stay moist.
When rain is scarce, soak the soil under the plants in the morning twice a week. Since tomatoes are susceptible to fungal disease, it's important to try and keep the foliage dry. Watering at the bottom and early in the day is the perfect combination to accomplish the chore.
Mulch is another key when fighting blossom end rot. It keeps the soil evenly moist. Give the plants a thick layer of straw and hopefully subsequent fruit will be fine as the season progresses.