My wife and I are first-year tomato gardeners. We decided to try growing tomatoes in 5-gallon containers. We have a total of 17 containers. About four of them are cherry-type tomatoes, but the rest are indeterminate varieties ranging from German Johnson to Pink Brandywine. My question, my problem: We are dealing with blossom end rot on all of the indeterminate tomatoes. I have used Cal/Mag and End Rot, bat guano, and tomato tone. I bought a cheap device to measure moisture and fertilizer, as well as pH, but we still are dealing with blossom end rot. Any advice on how we can combat this?
The Gardener’s Answer
It sounds like you and your wife have taken every measure to grow an abundance of organic tomatoes. Seventeen tomato plants for the first try is very impressive. Unfortunately, gardening can be frustrating especially when things don’t work out like we intended.
Blossom end rot is a common physiological disorder caused by inadequate growing conditions. A combination of uneven moisture levels and too much nitrogen makes tomatoes more prone to this disorder. Blossom end rot is caused by a calcium deficiency; either there is not enough calcium in the soil or the pH is off and binds the calcium so it’s not available to the fruit. We’ve had a lot of rain this season and fluctuations in soil moisture can be a problem especially if the soil does not drain well.
Growing tomatoes in containers is a great way to save on space, but if the containers do not have proper drainage the tomatoes will never be happy or productive. I assume your containers have plenty of drainage holes and are placed in a full sun location (a minimum of 6 hours). What is your watering routine? You always want to make sure that the soil is not moist before adding additional moisture. Avoid watering the foliage, and it is best to water in the morning. A thin 2-inch layer of mulch will help keep moisture levels consistent (even in containers).
Fertilizing with high amounts of nitrogen especially at rates higher than recommended can make our tomato plants more susceptible to this disorder as well. The recommended soil pH for growing tomatoes is between 6.5-6.7. The good news is that we still have plenty of growing season left and healthy tomatoes are hopefully in your near future.
For now, avoid adding fertilizer, keep soil on the dry side and discard all infected fruit. You have used top of the line soil and products to prevent blossom end rot, but sometimes less is better. I hope this is helpful and you have healthy, homegrown tomatoes very soon.