What Causes Tomato Rot

what causes tomato rot

Tomato rot is an increasingly pervasive problem both hobbyist backyard gardeners continue to experienced over and over. You walk into your garden to check on your tomatoes, then you begin to notice that some of them (if not all of them) seem to have a dark brown or yellowish patch at the bottom that makes them look rotten. 

What’s happening? As an advocate for backyard tomato gardening, I know what you are dealing with can cause worry over your tomato growing success. 

The most common problem, when it comes to growing tomatoes, is Blossom end rot. This condition is typically seen in half-grown fruits or very early in the season. So, what causes this condition? 

The real cause for blossom end rot in tomatoes is the lack of ample calcium supply in the tomato plants. According to research, an imbalance of calcium-rich soil where your tomatoes are growing causes a water-soaked spot to develop at your tomato fruits’ blossom end.

Symptomatic blossom-end rot is not exclusive to tomatoes, and it is a relatively prevalent problem for the gardener who grows tomatoes, pepper, squash, cucumber, and melon fruits as well as tomatoes.

As I have indicated that research shows that Blossom end rot is largely caused by the lack of calcium or calcium deficiency, does this mean you should rush to the store and buy calcium supplements? 

How To Prevent Tomato Rot Fast On Its Tracks?

Here’s A DETAILED GUIDE TO PREVENTING TOMATO ROT | Backyard blossom guides

No! Though tomatoes with blossom end rot are edible, preventing it by using suitable glow bags or recommended composite for your backyard long before you plant tomato seedlings is how you prevent tomato rot from happening. 

However, if you have an ongoing case of blossom end rot, mitigation measures is all you can do. This lack of calcium is also made worse by low water levels or irregular watering of the tomatoes in some cases

Increasing the watering and removing the tomato fruits with visible blossom rot helps to put a stop to the rotting of tomatoes.

I know this doesn’t sound like a lot to do when your tomato grow is falling apart. On a technically level, common sense would indicate that to tackle the brown spots on the bottom of the tomatoes caused by the lack of calcium you need more of it now. 

Instead of doing what most people do, thinking that adding calcium to the soil or replacing the calcium in the plant will correct the problem. Focus on mitigating steps and increasing the watering schedules to make sure the rest of your tomatoes does not develop the blossom end rot.

Still, calcium deficiency in soil is very rare case, I wouldn’t worry about it if its not happening. 

How Tomato rot Happens 

What happens is: when the tomato plant receives water in a short supply, it won’t able to transfer all the nutrients (including calcium) to the whole part of the plant as well as the fruits.

So, you have to make sure that you are watering the tomato plant on a regular basis, preferably per week. When watering, make sure that your tomato plants get at least 1 inch of water. Make sure that you don’t overdo it as this in another factor that can cause Blossom end rot.

What is Blossom End rot?

Blossom end rot (commonly called BER) is a physical condition that results in a brown or yellowish spot which starts to appear on the end of the fruit. For the most part, this color appears where the blossom was, resulting in the name Blossom End rot. 

As the tomato further grows, this brownish spot keeps on darkening, eventually becoming black and leathery. Often, this condition may even cover half of the tomato’s bottom area.

The worse part about Blossom end rot is that this tomato problem doesn’t appear until the tomato starts to ripen, and by that time, the damage has already been done. On top of that, the rest of the tomatoes that are on the same plant will eventually follow suit. 

As we said earlier, the lack of calcium is the great cause of the brown spots, but this is only because the plant didn’t receive enough water to absorb enough calcium and distribute to the rest of the plant. 

Besides the lack of irregular watering, Blossom end rot can also be intensified by the following conditions. 

Uneven watering due to drought

Due to drought, tomato plants can’t be watered as much as they would be in an abundant supply of water. As such, the plants won’t be able to take up enough nutrient to keep up with its growth. This will undoubtedly lead to Blossom end rot. 

Tomato Rot Caused By Fast climbing temperatures

Fast-climbing temperatures are another factor that can lead to blossom end rot in tomatoes and other vulnerable fruits, such as peppers, squash and eggplant.

Tomato Rot Caused By Too much nitrogen fertilizer 

Nitrogen fertilizer naturally enriches the leafy part of the plant. This eventually diverts all the nutrients away from the plant’s fruits. 

Too much salt in the soil

When there is too much salt in the soil, the plant won’t be able to take in enough water. This means the plant won’t absorb an adequate amount of nutrients to support the growth of the fruits, which will lead to Blossom end rot. Most times, high levels of salt in the soils are caused by an excess use of artificial fertilizers.

Root damage

Damaged roots will automatically be restricted from taking up enough water and nutrients for the plant. Root damaged is primarily caused by cultivating animals.

Tomato Rot Caused By Soil irregular pH Levels

The pH levels in the solid may either be too high or too a little low in supply for the tomato plants to access the nutrients in the soil. Normally, tomatoes will flourish on a soil that has a pH level of around 6.5.

How can you stop Tomato Blossom Rot?

The most unfortunate part about tomato blossom is that it can’t be fully cured. Obviously, nature is uncontrollable. 

However, tomato blossom end rot can be somewhat lessened to a certain level by the appropriate taking steps towards the improvement conditions that foster its development. 

In other words, you can be able to control some factors, such as like poor soil, watering and fertilizing. Alternatively, you can take on methods that will help you in avoiding Blossom end rot altogether. 

Planting tomatoes in a great soil that has been corrected with organic matter will go a long way in giving the plants just what they need to develop healthy growth earlier in the season. 

This means you won’t have to add any dose of fertilizer to your tomato garden, as this may complicate things. 

If you still feel the urge to apply some fertilizer, it is recommended that you should choose the fertilizers that are lower in nitrogen tomatoes, and apply the fertilizer in the recommended methods and rates. 

As we said before, it is very important that your tomato plants are provided with the right amounts of water. Also, consider adding a mulch as this can help retain moisture while keeping the soil as well as the plant roots shielded.

Other Common Tomato Plant Problems

Now that we have looked at the causes and how you can deal with Blossom end rot, let us explore some of the other problems that are encountered by most tomato gardeners out there. 

As we said before, when you know your problem at an early stage, you have a chance to fix it before it spreads to all your other tomatoes. A majority of tomato gardeners have pointed out these problems

Ripening Tomatoes That Crack 

The cracking of tomatoes is another tomato problem that seems to affect a majority of tomato gardeners. 

For the most part, tomatoes crack when they are not watered frequently. So, when we go for a while without watering them, we try to make up for it with too much watering. 

This causes the pulp inside the tomato to hold the water, which eventually makes it swell up at a faster rate than the outside of the tomato can actually stretch. This causes outside of the tomato to split open, hence the cracks.

To prevent cracking, you have to ensure that you water your water your tomato plants on a regular basis. As we pointed out earlier, you should water your plants weekly. 

Though the cracking of the tomatoes can be an issue, the tomatoes are perfectly edible. Just make sure that you use them straightaway as the cracks start developing mold after a while.

Green Shoulders

Tomato “Green Shoulders” is defined as a condition in which the larger part of the tomato ripes, but the area near the stem remains green and solid. 

In other words, the tomato never fully becomes ripe. You can wait for a longer time but the tomato still won’t fully change to the red color. 

There’s also a similar condition called “Yellow Shoulders”, which is said to occur when the level of lycopene production is slowed down. 

Compared to Blossom end rot, Green shoulders and yellow shoulders are said to be a lot more complicated.

A lot of factors can play into the cause of these conditions. These are factors such as sunlight and weather. Sometimes it could simply be the type of tomato that you are growing. 

To prevent this problem, ensure that your tomatoes have been covered in a shade, and pick them early if the heat seems intense. 

Even though green shoulders can be a great disappointment, the portion of the tomato that has fully ripened is still fully fit for consumption. So, you will simply slice off the green portion and enjoy the red part. 


To sum up, Blossom end rot occurs because the plant simply cannot take enough calcium out of the soil at a rate that will enable it to keep up with the growth of the entire plant. 

Another reason may be that the plant is stressed. Plant stress generally causes the plant to be unable to process the calcium that it takes up.

Despite the fact that you cannot save the fruits that have already been affected with blossom end rot, you can save the rest of the season by being cautious about watering and mulching around the plants in order to conserve moisture and other issues. 

All things considered, the majority of tomato plants will at some point be affected with blossom end rot. In most cases, however, this condition will normally clear up on its own without any major ill effects on all your plants. 

As for the fruit that has been affected, you can simply be picked off, and you have the choice to completely discard them or cut the bad parts out of the more ripened ones and eat the rest.

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