Blossom End Rot

If you’ve ever grown tomatoes, chances are you’ve run into this problem at least once. Those gorgeous green tomatoes (and usually the first ones of the season!) will develop and ugly brown-black, rotten looking area. It could be only a small spot, but in severe cases it can take up to half the tomato. This is not some deadly tomato disease, but a disorder known as Blossom End Rot.

The disorder is technically caused by a calcium deficiency – there isn’t enough calcium getting to the fruit, which causes the cells to collapse and “rot.” However, don’t run off looking to apply a bag of calcium to your soil. Most soils have plenty of calcium! (Although some gardeners swear by putting some eggshells in the hole when planting their tomatoes.) The real culprit is some combination of the weather and you and your watering practices.

As I said, most soils have plenty of calcium. What happens is that there is not enough water to transport the calcium from the roots of the plant to the fruit. It is pretty common that at some point in the spring to early summer the weather patterns and our watering schedule result in the soil going from nearly soggy to bone dry. Tomatoes are very sensitive to that bone dry soil. The best way to prevent the blossom end rot is to keep the soil evenly moist.

That being said, certain varieties of tomatoes are more susceptible to blossom end rot. On those varieties, the first flush of fruit will have it no matter what you do. Luckily, it almost always clears up after the first few fruit unless the water situation is particularly severe. So, pick off the affected tomatoes, take care in your watering, and be patient. You’ll be flooded with good tomatoes soon enough!