Most vegetable gardeners have dealt with blossom end rot. It’s a very frustrating problem to have. One day you’re walking through your tomato patch admiring your first plump green tomatoes and suddenly you notice that some are developing a brown mushy bottom.
It is most commonly seen on young plants and starts as a brown or black spot on the blossom end of the fruit. The spot will usually get larger and continue to rot if the fruit is allowed to remain on the plant.
What is blossom end rot?
Blossom end rot is a disorder of growing fruit that causes the cells at the blossom end of the fruit to die. And it’s not isolated to tomatoes. Peppers, eggplant, squash, and watermelon can all be plagued by the brown and mushy bottom disease.
Myth 1: Blossom end rot is caused by a deficiency of calcium
While the cellular death involved in blossom end rot is certainly a result of a lack of calcium, it is important to take note that the deficiency of calcium is isolated to the affected fruit. Studies have indicated that the soil, leaves, and stem of plants affected with BER usually have adequate calcium. It seems that during periods of stress, the plants will divert nutrients to the leaves and stems of the plant. As a consequence, the fruits may be deprived of calcium and develop blossom end rot. (see related article here)
Myth 2: You can prevent or treat blossom end rot
I know. I know. A lot of readers are going to strongly disagree with me. But the reality is that blossom end rot is a complex process that cannot be addressed the same way from plant to plant and gardener to gardener. What has seemed to work for some gardeners will not necessarily work for other gardeners.
Some commonly recommended preventatives include:
Heavily mulching with calcium rich compost
Some say that heavy mulching will protect your plants from the water stress which may lead to blossom end rot. It is true that blossom end rot can be caused by water stress, so preventing that with whatever means you choose can help. However, unless you’ve had a soil test to confirm that your soil is deficient in calcium (which is usually not the case), adding calcium to the soil will not help prevent or treat blossom end rot.
In fact, some suggest that the mulching might encourage rapid growth which may lead to blossom end rot.
Planting tomatoes with Epsom salts and crushed eggshells
Epsom salts contain magnesium and sulfur. These are important nutrients for plants, so if your soil is deficient in magnesium and sulfur, then it will help your plants. Eggshells do contain calcium, but the calcium from the eggshells will not immediately be available for uptake by the plants.
So, while not harmful to the plant, neither Epsom salts nor eggshells will affect the development (or not) of blossom end rot.
Adding lime or dolomite lime to the soil
It is true that lime can improve the quality of your soil. It adds calcium and dolomite lime contains magnesium. If your soil is acidic, the lime will also help neutralize the pH into a comfortable range for your plants. The ideal soil pH varies between plants, but is usually about 6.5. Once in the appropriate pH zone, your plants will be better able to absorb and use the calcium in the soil.
However, you should always check the pH of your soil before adding lime. If you get your soil pH too high, it can be hard to grow anything. It’s super easy to find out the pH of your soil with a soil pH kit .
Foliar and fruit sprays
There is insufficient evidence to support that tomatoes can absorb calcium through the fruit or will transport calcium supplementation from the leaves to the fruit. The problem is usually not a lack of available calcium anyway. The problem is that the plant is sending available calcium to other parts of the plant.
A better way to address blossom end rot is to make sure that you are watering regularly, but not over-watering, and fertilizing appropriately, but not over fertilizing.
The good news is that blossom end rot will usually go away on its own. Yay!
This seems to be a condition that most plants will grow out of. So if your first round of tomatoes goes all brown and mushy on the bottom, don’t panic!
There are some types of tomatoes that are more prone to blossom end rot. We’ve certainly experienced years where we lost most of the tomatoes on some plants due to blossom end rot.
Paste type tomatoes do seem to be more prone to this problem while it is less common in cherry tomatoes.
However, I’ve seen it on pretty much every type of tomato, as well as squash, watermelon, and peppers.
If you find that your veggie patch is plagued by blossom end rot this year, the first thing to do is get a soil test to make sure that your soil is within the appropriate pH range and has adequate nutrients. The next thing to do is pull off those mushy fruits and toss them into the compost or the chicken pen. And take heart…
You didn’t do anything wrong, and there’s nothing you can do to fix it.
You can, however, avoid the problem by planting a more resistant variety. So make sure you’re taking notes about your garden every year so you can avoid varieties that don’t perform well.
I’d love to hear your thoughts on this subject. Please leave me a comment below.