Attack of the Rotten Tomatoes

Blossom end rot on our roma tomatoes.

Dear reader, it seems we never run out of problems in our little garden (Good thing we never said we were experts). Our loss is your gain though. We planted a Roma tomato plant a few weeks ago. Everything was progressing nicely. The plant was growing, flowers were blooming, fruit was growing. How happy we were. That would soon change (yes, I'm being overly dramatic but editorializing is "in" these days).

We started noticing a small dark spot on the bottom of one of the fruits. "No big deal" I thought, probably a bird nibbled on it. It's salvageable. The next day the spot was larger. The day after that the spot was even larger and an adjacent tomato also had a similar spot. Houston, we have a problem. (Good thing I had foreshadowed this in the previous paragraph or you would be in for a surprise at this point).

The problem? Blossom end rot. Actually, if we were to go overly technical (which I tend to) the problem is calcium deficiency. "Blossom end rot" is just a description of what we see. Now at this point you are probably thinking "I'll just add calcium to the soil and fix the problem". Having proper amounts of calcium at the time the fruit sets prevents blossom end rot which is why we recommend placing crushed egg shells near the roots when transplanting tomatoes, peppers or any other member of the Nightshade family. However, more often than not the cause for the calcium defficiency is not a low amount of calcium in the soil but rather one of the following: uneven soil moisture, improper use of high nitrogen fertilizer, or high amounts of phosphorus.

This disorder typically affects the first fruits of the season and once it presents itself it is very hard to overcome. Therefore, the best strategy is prevention. If you use a high quality potting soil phosphorus shouldn't be a problem. Also, if you follow the manufacturer recommended dose and fertilize every other week excess nitrogen shouldn't be a problem. In any case we recommend light fertilization when the first fruit are being set. That leaves us with uneven moisture which is the most likely cause for blossom end rot in the tropics (sure enough this was our problem). Due to the large amounts of rainfall followed by very hot temperatures maintaining a constant moisture level is always a struggle. We offer the following three tips to help overcome this challenge.

1. Mulching - Mulch reduces evaporation and helps maintain moisture in the soil. 
2. Plant placement - Placing your plants in an area where rainfall doesn't fall on them will also help you be in control of moisture rather than being at the mercy of nature. 
3. Watering - Proper watering is very important not just to prevent blossom end rot but to achieve healthy plant growth. Watering is, in theory, simple. Don't overwater your plants and don't let them dry out. In practice, watering requires knowledge, skill, experience, and intuition. A good rule of thumb is to touch the soil. If it feels hot it needs water; if it's cool it doesn't need water. However, each plant has different moisture needs which is why we say several attributes are needed in practice.

We hope you never encounter blossom end rot but if you do we hope this post helps. Just remember to be patient. It takes time to heal after all.