Blossom end rot occurs because the soil in your home vegetable garden is deficient in calcium. It also occurs when the weather in your area has been considerably wet followed by an immediate dry period.
Blossom end rot most notably affects peppers, squash, tomatoes and watermelon. As you can see in the picture, it looks like a dark circle and spreads to the end fruit as the vegetable will then look like it is rotting.
If not taken care of it could spread to the remaining of the unaffected portion of your garden and also lead to additional or secondary rotting.
Here are steps you can take to control blossom end rot in your home vegetable garden.
Prior to planting any vegetables, always obtain a pH level reading on your soil conditions. You can obtain good testing kits at your local garden center that will give you the amount of calcium you have in your soil.
After you obtain your test readings form your soil test kit as per step one, you will be able to tell if your soil is low in calcium. If you need to add calcium to your soil you have a variety of choice to do so, but the best, fastest acting as well as comparably affordable is more than likely limestone.
The test kit you purchased in step one should also give you the pH reading. If the pH reading is not highly acidic then add a little gypsum to bring the pH level to a more stable reading.
Finally, make sure you add some mulch over top over your topsoil so that the ground maintains an even moisture level and avoid excessive fertilizing so you do not throw out of balance all of the work you did in the previous steps. Just continue to monitor your soil conditions throughout the growing season and make adjustments as necessary.