How to prevent tomato rot?

How to prevent tomato rot?

Blossom end rot, commonly known as tomato rot is one of the most disappointing things when growing tomatoes in your backyard or potted vegetables on your apartment balcony. 

And, if you are growing vegetables of any sort, one way or the other you are going to notice that your tomato garden is falling apart. Though tomato rot is preventable, dealing with it as it’s happening is something you can’t control. 

Luckily, preventing blossom rot long before it happens is always better than trying to fix it when your tomatoes are rotting. 

The most common question that hobbyist tomato gardeners normally ask is how to ensure that blossom end rot is prevented. 

We all want to understand why we have a black scab that occurs on tomatoes. So how do you prevent Blossom end rot?

Here are a couple of steps that you can take to ensure that you have prevented Blossom end rot. Let’s discuss them. 

Check the pH level of your garden’s soil

In tomato gardening and many other fruits, the pH level is a very important variable that will really mean the difference between growing healthy fruits or not. That said, consider growing tomatoes in well-drained soil with a soil pH level ranging between 6.5 and 7.5. 

Avoid deep cultivation around the tomato plants. 

You should try as much as you can not to cultivate your plants. Tomato roots are quite vulnerable, especially in the drier seasons. So, after fruit set, only fiddle around your tomato garden when you want you get rid of the weeds, and when you do, do it lightly with a hoe. 

Maintain a consistent supply of soil moisture

Normally, tomatoes need at least 1 inch of water per week, particularly when the fruit is developing in the growing season. This water can either be supplied as rainfall or irrigation. Watering with a soaker hose is better than setting up overhead irrigation in the home garden.


If you prefer to apply fertilizer or lime, use the recommendations made by a soil test. For a tomato garden, it is better to use fertilizer that is low in nitrogen. This is because nitrogen is highly associated with leafy growth. As such, this might divert the nutrients away from the fruits, leading to blossom end rot. On top of using fertilizers that are low in nitrogen, you should pick the ones that are high in superphosphate, with numbers similar to 4-12-4 or 5-20-5. This will likely reduce the probabilities of blossom-end rot.


When you mulch your tomatoes, you are conserving moisture in the soil. Consider using organic mulches such as straw free of weed seed, peat moss or even wood chips- whichever works for you. 

Remove infected fruits

When you first notice a sign of blossom end rot in some of the fruits, you should remove them immediately. This rot does not actually spread from plant to plant or from fruit to fruit though, so even if it occurs on your earliest tomatoes, it will not necessarily affect later tomatoes on the same plant. 

A little About Blossom end rot 

It can be a stressful experience for home gardeners to notice that a dry and sunken decay is developing on the tomatoes’ blossom end in their garden. 

For the most part, this is noticed on the first tomatoes of the season that have been carefully cultivated or after an extremely dry period in the summer season. 

Blossom end rot is a physical condition that results in a brown or yellowish spot which appears on the end of the fruit, particularly, where the blossom was, hence the name Blossom End rot. 

This disorder is very common in tomatoes while it is less frequent in other fruits such as peppers or even eggplants. Almost everyone growing tomatoes has gone through this experience before, and it is not fun. 

The condition first appears as water- soaked spots on the bottom of the tomato. In the end, the tissue that has been affected breaks down rapidly and the area becomes sunken, dark brown or black, and leathery. 

Blossom end rot is common in tomatoes that are in the mature stage and most often on the first tomatoes of that season.

What causes Blossom end rot?

Blossom-end rot is largely caused by insufficient calcium in the tissue of the tomato. In this case, calcium is taken up into the plant through the roots and ends up settling in one part of the plant. 

On the other hand, this means that the rot can occur even when there is an abundant supply of calcium in the soil, stems, or even plants’ leaves. 

As such, tomatoes must have a continuous supply of calcium to prevent these dry and dark spots from developing on the blossom end, especially the plants that have developing tomatoes.

The conditions that cause blossom-end rot are mostly related to inconsistent soil moisture throughout the entire growing season. Since calcium is only moved into the plant with a sufficient moisture supply, drought will lead to calcium deficiency.

Rapid early growth of the plants is another problem that can cause blossom end rot, mostly because the, as we mentioned before, calcium is needed by the tomatoes when they are in the active growing stages, and the plants may not be able to take up sufficient calcium quickly enough to keep up to the fast growth rate of the plants.

Although it can be very difficult to wait for those first ripe tomatoes from your home garden, you should not try to force the tomatoes to grow quickly by applying any artificial substances. If the plants grow too quickly, blossom end rot will likely occur, so it is important not to force the plants to grow too quickly to avoid the development of this rot.

Also, Root damage is another problem that can lead to decreased moisture intake. Root damage is mostly caused by cultivating too close to plants or even burning them with fertilizer. 

This can have the possible effects of reducing nutrient and water uptake through the roots to the rest of the plant. Waterlogged soils are also another factor that interfere with the ability to take up nutrients through the roots.

Besides the problems mentioned above, the factor may simply be that your garden soils have low calcium levels. This can be determined by soil testing. The low calcium levels in your soil can be corrected by adding lime as recommended on the soil test report. 

Controlling Blossom end rot

Blossom end rot is generally triggered by two things: a lack of calcium and an inconsistent watering. As we mentioned before, preventing the problem is always best. But what if the problem already started? Is there a way we can control or reverse the effects of Blossom end rot? There sure is. 

Here’s how.

Step 1: Remove all Affected Tomatoes

The most unfortunate part about blossom end rot is that once a tomato has developed this disease, it won’t really go away.  

However, you can still manage to save the tomato plant and any remaining tomatoes that it produces. Consider putting all the rotten tomatoes in your compost.

Step 2: Water your tomatoes with Powdered Milk

Generally, tomatoes that have blossom end rot need to be provided with plenty of calcium at the root. While most people recommend that you use eggshells, the plants won’t take up the calcium until the eggshells have started decomposing, which can take several weeks or even months, depending on the weather. So, eggshells won’t really help solve your problem. 

Instead of going with the idea of eggs shells, you can simply mix powdered milk into your watering can for a quick hit of calcium that will easily be taken up by the roots and transported to the rest of plant. What about lime? Well, it should only be used when you notice that your soil has a problem of the pH level. For the most part, lime tackles this problem. 

Step 3: Water Every Day

Consider watering your tomato plants on a daily basis. You can also water them twice a day, especially in times of extreme heat. 

Generally, tomatoes require consistent water.  

In fact, when you are not watering them very early in the season, Blossom end rot will likely develop of some or all of the tomato plants. 

However, you still have a chance to reverse blossom end rot when it is in its earliest days. You can reverse it by consistent watering. 

Step 4: Mulching 

The final step in controlling blossom end rot is setting up a mulch. Consider surrounding your tomatoes with 2-4 inches of shredded newspaper or wood chips. This easy organic mulch will help your tomato plants to retain moisture. 

Besides that you will prevent the growth of weeds, and add more nutrients to the soil in the long run.


In summary, the few things you can do to prevent the development of blossom end rot are:

  •  Checking your soil has enough supply of calcium.
  • Monitoring the pH level of your garden’s soil. 
  • Avoiding deep cultivation around the tomato plants.
  • Maintain a consistent supply of soil moisture.
  • Using fertilizers that are low in nitrogen but high in superphosphate.
  • Mulching around the tomato garden and removing all the fruits that have already been infected with blossom end rot.

Recent Posts