Mad About Berries

Tomato Blossom End Rot - Causes and Solutions

Tomato Blossom End Rot is a common garden problem that affects a wide variety of tomato and pepper plants.

Despite its name, it is not a plant disease. It's a physiological disorder caused by a lack of calcium at the growing tip of the fruit.

Published: July 29, 2023.

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What is Tomato Blossom End Rot?

Blossom end rot is a prevalent gardening issue that results from a deficiency of calcium in the plant. This disorder is not exclusive to tomatoes; it can also affect fruits like peppers, squashes, cucumbers, and melons.

It's crucial to understand that it is not an insect-related problem, hence there's no need to resort to widespread insecticide usage.

The onset of blossom end rot is often observed when the initial phase of the growing season is damp, shifting to dry conditions when the fruit is developing.

The primary symptom of this disorder is a moist spot appearing on the end of the tomato fruit where the blossom was, which becomes evident when the fruit is about halfway grown.

These damp spots eventually enlarge, transforming into a dark brown, leathery texture. Ultimately, these areas begin to decay, which indicates that it's time to remove and discard the affected fruit.

What Causes Tomato Blossom End Rot?

Calcium deficiency can happen due to a few reasons:

  • Inadequate calcium in the soil: If the soil is naturally low in calcium, the plants will not be able to absorb the necessary amount for healthy growth.
  • Improper watering: Fluctuations in soil moisture levels can affect the plant's ability to absorb calcium. Both overwatering and underwatering can lead to blossom end rot.
  • Rapid plant growth: A sudden growth spurt, often due to abundant nitrogen fertilizer, can cause blossom end rot. The rapid growth can lead to a temporary calcium deficiency in the new tissues.
  • Damage to roots: If the plant's roots are damaged or stunted, they may not be able to absorb enough calcium from the soil.
  • High levels of salts in the soil: High salinity can reduce the uptake of calcium.

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How To Prevent Tomato Blossom End Rot?

Preventing Tomato Blossom End Rot involves several steps focused on maintaining optimal growing conditions for your tomato plants:

  • Ensure adequate calcium levels: Check your soil's calcium levels before planting. If the soil is deficient in calcium, you can add lime or gypsum to increase the calcium level.
  • Maintain proper pH: Tomatoes prefer slightly acidic soil with a pH between 6.0 and 6.5. When the pH is in this range, it is easier for the plants to absorb calcium from the soil.
  • Water consistently: Irregular watering can lead to Blossom End Rot. Water your plants regularly to keep the soil consistently moist, but not waterlogged. Avoid allowing the soil to become overly dry between watering.
  • Avoid high nitrogen fertilizers: Excessive nitrogen can interfere with the absorption of calcium. Use a balanced fertilizer and avoid those high in nitrogen, especially ammonium-nitrogen.
  • Care for the roots: Avoid damaging the roots of the plant, as damage can inhibit the plant's ability to absorb calcium from the soil.
  • Mulch around the plants: Mulching helps conserve water and keep the soil moist, reducing the risk of Blossom End Rot.
  • Plant resistant varieties: Some tomato varieties are more resistant to Blossom End Rot. If you're struggling with the issue, consider planting one of these varieties.

Note that even with all these preventative measures, some years may be more conducive to blossom end rot than others, especially those with extreme weather fluctuations. So don't be too hard on yourself if you experience some loss to Blossom End Rot.

What Are Typical Tomato Blossom End Rot Home Remedies?

Here are a few home remedies gardeners often use to prevent and manage tomato blossom end rot:

  • Lime or Eggshells: As blossom end rot is caused by calcium deficiency, adding lime (calcium carbonate) to the soil can help to increase its calcium content. Some gardeners also use crushed eggshells, which are rich in calcium, though it takes a longer time for them to break down and become available to the plants.
  • Calcium sprays: There are commercial sprays available that provide foliar calcium. Some gardeners also make a homemade calcium spray using calcium nitrate or calcium chloride. However, these sprays generally provide only a temporary fix and do not address the root cause of the problem, which often lies in the plant's water supply and soil conditions.
  • Consistent watering: As inconsistent watering can cause blossom end rot, maintaining a regular watering schedule can help to prevent it. Using a drip irrigation system or soaker hoses can provide slow, steady water that encourages the steady uptake of calcium.
  • Proper fertilizing: Using a balanced, slow-release fertilizer can help to prevent nutrient imbalances that might exacerbate blossom end rot. Avoid using high-nitrogen fertilizers, as they can hinder calcium uptake.
  • Mulching: Adding a layer of organic mulch around your plants can help to retain soil moisture, prevent extreme fluctuations in soil moisture levels, and gradually add nutrients to the soil as it decomposes.

It is highly recommended to test your soil before amending the soil, as adding too much of a nutrient can cause its own problems.

And while these home remedies can help to manage blossom end rot, they may not completely eliminate it, especially in years with particularly challenging weather conditions.

Is Epsom Salt Good For Tomato Blossom End Rot?

Epsom salt, or magnesium sulfate, is often used in gardening and can be beneficial for some plants under certain conditions as it provides magnesium, which is an essential nutrient. However, it is not typically a solution for tomato blossom end rot, which is caused by a lack of calcium in the plant, not a lack of magnesium.

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While Epsom salt can help in cases where the soil is deficient in magnesium, it doesn't provide the calcium that plants need to prevent blossom end rot. If your soil is deficient in calcium, you'll need to add lime or a specially formulated calcium supplement to your soil. It's always a good idea to test your soil before adding any supplements, as adding too much of a nutrient can also cause problems.

In fact, too much magnesium from Epsom salt can even compete with plants' uptake of calcium, potentially worsening the problem. Therefore, using Epsom salt as a remedy for blossom end rot is not typically recommended. Instead, focus on maintaining balanced soil nutrients, providing consistent water, and avoiding root damage to help prevent blossom end rot.

For more about this topic, feel free to check our Epsom Salt for Tomatoes: Benefits and Limitations article.

Can Calcium Citrate Help With Tomato Blossom End Rot, How To Apply It, And How Much?

Calcium citrate is a source of calcium that could potentially be used to address the calcium deficiency contributing to blossom end rot in tomatoes.

However, it's not a common solution, and there isn't extensive research or guideline on its use in this context.

It's important to know that simply adding calcium to the soil is not always the solution, as the problem often lies more in the plant's ability to uptake calcium, which can be impacted by factors such as inconsistent watering, root damage, and improper soil pH.

That said, if you want to use calcium citrate as a soil amendment, here's a general guideline:

  • Crush the tablets: You'll need to begin by crushing the calcium citrate tablets into a fine powder.
  • Mix with water: Dissolve the crushed tablets in water. The amount will vary depending on the size of your garden, but a general guideline might be one tablet per gallon of water.
  • Apply to soil: Pour the mixture around the base of the plant. Avoid pouring it directly onto the plant itself.
  • Regular application: Apply this solution once a week during the growing season.

Before applying anything to your soil, it's generally a good idea to test your soil's nutrient levels and pH. This can help you determine if your soil is actually deficient in calcium (probably not) or if the problem lies elsewhere.

Additionally, adding too much calcium can lead to nutrient imbalances, so it's important to be cautious when using supplements.

Also, remember that while adding calcium can help prevent blossom end rot in some cases, maintaining a consistent watering schedule and avoiding root damage are often just as, if not more, important.

Can You Eat Tomatoes With Blossom End Rot?

Yes, tomatoes with blossom end rot are safe to eat. The rot itself is not caused by a pathogen, but rather a physiological condition due to a lack of calcium, and it doesn't make the tomato toxic or harmful to humans.

However, the affected part of the tomato is typically tough and leathery, and it may have a distinctly unpleasant taste. Therefore, it's generally recommended to cut away and discard the affected part before eating the tomato.

Also, do check carefully for any signs of mold or secondary infection in the rotted area, as these could potentially be harmful.

If you notice any such signs, it's best to discard the whole tomato to be on the safe side.


Few Final Words

From time to time, people ask us if Calcium Malate is better than Calcium Citrate. Well, Calcium Malate is more easily absorbed than Calcium Citrate in - the human body!

Tomato Blossom End Rot is rarely caused by calcium deficiency, especially in tomatoes fertilized using organic fertilizers and watered regularly.

So, if your growing tomato fruits get Tomato Blossom End Rot, start watering your tomatoes regularly (don't overwater them) and check the pH levels of the soil.

Amend the soil only if the pH test results are way off the required values.

Note: be very careful not to damage the roots when applying the new fertilizers and cleaning the weeds since damaged roots may also cause a decrease in calcium uptake.

Tomato Blossom End Rot can be avoided, but even when it happens, it can be stopped relatively easily.

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