Blossom end rot on tomatoes
Blossom end rot is not a disease or a pest. It is simply the result of a calcium deficiency. Tomatoes are commonly afflicted by this deficiency, but other fruiting vegetables can be susceptible as well.
Top of the cherry tomato Bottom of the cherry tomato
How do you get a calcium deficiency?
If you are building healthy soils through good compost, manure, and mulch you will probably not have too much of an issue with blossom end rot. However if you have good soil, but you are still experiencing these issues, you are probably watering too much. Whenever you irrigate, or it rains for that matter, some of the nutrients in the soil are washed out of the root zone, or leached. If you are watering too much, this can wash the calcium out of the soil leading to a deficiency.
So what do you do about it?
Prevention is the key, if you are building good soils, and you are not overwatering you should not have too much of an issue with this. Unfortunately, there is not much short term that you can do to remedy this issue. You could add compost or better yet compost tea, but it may not take effect in time to “fix” things. It is a good idea to remove the damaged fruits immediately when you notice the rot. This will remove some of the stress, and why waste the plants nutrients on fruit you’re not going to eat.
Container grown tomatoes
I transplanted quite a few tomatoes into my garden plots at the beginning of May, and I also had some tomatoes growing in 15 gallon pots that I put outside as part of my container garden around the same time. At first my container grown plants vastly outperformed my transplanted tomatoes, but over the past 3 weeks or so, my in ground tomatoes have quickly overtaken my container tomatoes in size and health. Some of my in ground tomatoes are twice the size of my container grown tomatoes, and some of my container grown tomatoes have blossom end rot, while my in ground tomatoes are completely healthy.
I believe what happened was at first the transplant shock slowed down my in ground tomatoes, but then once rooted with tons of soil to grab nutrients from, they took off. Meanwhile, my container tomatoes are limited to the soil in there pots, which are large, but not as good as in ground. Furthermore, I have probably watered my container tomatoes too much. I haven’t watered my in ground tomatoes at all, but the containers seem to dry out quickly, so I have watered my containers every 4 or 5 days or so. I think this was enough to wash out enough of the calcium to cause the blossom end rot. I did mulch my potted tomatoes to lessen the irrigation requirements, and I removed two rotting tomatoes, but I’m not going to do anything else at this point.
In ground tomatoes growing out the top of the cages/ Container grown only half way up the cage