Tomato Rots On Bottom – Identifying Tomato Plants With Blossom Rot

Image by Scot Nelson

By Nikki Phipps (Author of The Bulb-o-licious Garden)

Have you noticed tomato fruit that looks rotten on the bottom? A common problem in the garden, especially when growing tomatoes, and a commonly asked about topic, blossom end rot is usually seen in half grown fruits or early on in the season. So what is tomato blossom end rot and what, if anything, can be done about it? Read on to learn more.

Causes of Tomato Blossom End Rot

Blossom end rot (BER) is a physiological condition that results in a brown or yellow water-soaked spot which appears on the end of the fruit where the blossom once was. As the tomato grows, this spot darkens, eventually becoming leathery and black, and may even cover half the fruit’s bottom.


Often blossom end rot in tomatoes is blamed on a lack of calcium, either by depleted, poorly drained soil or simply from displacement due to transpiration, especially when plants are under stress. Technically, brown spots on tomatoes from blossom end rot is caused by this lack of calcium. For this reason, you often see it recommended that you should add calcium to the soil or replace the calcium in the plant through a foliar application in order to help correct the problem. But it is actually very rare for soil to be lacking in calcium.

Instead, there can be a number of other environmental causes of tomato blossom end rot, from uneven watering due to drought, heavy rainfall or an over caring gardener. Rapid plant growth, especially if given an overabundance of nitrogen early on, as well as fast climbing temperatures can contribute to blossom end rot in tomatoes and other susceptible fruits, like peppers, squash and eggplant.

Blossom end rot occurs not because the soil lacks calcium but because the plant simply cannot take calcium out of the soil at a fast enough rate to keep up with the growth of the plant or because stress causes the plant to be unable to process the calcium the plant does take up.

How to Stop Tomato Blossom Rot

Unfortunately, this disorder cannot be fully “cured,” as you can’t control nature. That said, tomato blossom end rot can be somewhat alleviated or managed to a certain extent by taking steps to improve or avoid conditions that foster its development – at least those more easily controlled by the gardener, like poor soil, watering and fertilizing.

Planting tomatoes in a timely matter and in a well-draining soil amended with organic matter will go a long way in giving the plants exactly what they need to develop healthy growth early on, which means that extra dose of fertilizer isn’t necessary. And if you do fertilize tomatoes, opt for one that is lower in nitrogen and only apply at the recommended rates, or cut by half.

Providing adequate and even amounts of water for tomato plants is important too. The addition of mulch can help retain moisture while keeping the soil and plant roots insulated.

While it may or may not be effective, and is a highly debated topic, the addition of crushed eggshells, limestone or calcium carbonate in the soil won’t necessarily hurt, but it may not help much either.

All in all, the majority of tomato plant varieties will at some point be affected with blossom end rot. But, in most cases, as the season progresses, this condition will normally clear up on its own without any major ill effects. As for the fruit suffering from tomato blossom end rot, these can simply be picked off and discarded or cut the bad parts out of larger, more ripened ones and eat the rest – it won’t harm you.

Print This Article
This article was last updated on
Did you find this helpful?
Share it with your friends!

Additional Help & Information

Didn't find the answer to your question? Ask one of our friendly gardening experts.

Do you know anything about gardening? Help answer someone's gardening question.

Read more articles about Tomatoes.

Search for more information

Use the search box below to find more gardening information on Gardening Know How: