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Calcium for Tomato Plants: Do tomato plants like it?

Why Tomato Plants Like Calcium

Did you think calcium was only for humans? Think again!

Tomatoes need different nutrients to grow well, just like any plant in your garden. One of these nutrients is calcium. 

Surprisingly, even with enough calcium in the soil, tomato plants might still suffer from lack. But on the other hand, adding too much calcium to the soil can cause issues. 

Let’s find out how calcium is good for tomatoes and how to spot a deficiency.

Do tomato plants need calcium?

Do tomato plants need calcium
Image by Love the Garden

Tomato plants need calcium to grow and stay healthy. It’s essential for their development and productivity. 

You can tell if they have enough calcium by observing their growth and how they look. It’s because having sufficient calcium is crucial during fruit development. 

Calcium ensures a healthy fruit set and proper growth. To prevent issues like blossom end rot, which causes dark spots on fruits, give your tomato enough calcium.

Calcium also boosts the plant’s immune response and disease resistance. Well-fed tomato plants can fend off pathogens and are less likely to get sick.

If tomato plants lack calcium, they may show symptoms like yellowing leaves, leaf curling, and stunted growth. Calcium also affects fruit quality, making tomatoes firm and less susceptible to damage.

Lastly, calcium aids nutrient absorption and transport in the plant. When tomatoes have enough calcium, they can effectively use nutrients like potassium and magnesium.

Do tomato plants like calcium?

Do tomato plants like calcium
Image by The Old Farmer’s Almanac

Yes, tomato plants like calcium. Calcium is a must-have for robust tomato plants. 

It’s not just about growth and fruit development. Calcium plays a pivotal role in shaping cell walls and the overall structure of the plant.

How to Add Calcium to Tomato Plants

How to Add Calcium to Tomato Plants
Image by Garden Patch

Ensure your tomato plants get enough calcium if they show deficiency. Before adding anything, conduct a soil test to check calcium levels.

By doing this, you can avoid applying too much calcium and address the deficiency. Use calcium-rich materials like agricultural lime, gypsum, crushed eggshells, foliar sprays, or calcium-based fertilizers based on the soil test results.

Agricultural Lime

If the soil is acidic, adding agricultural lime will raise the pH and provide calcium over time. Use the recommended application rates based on the soil test.


If your soil pH is already right, but it needs calcium, consider using gypsum, also known as calcium sulfate. Just spread it on the soil surface and water it in.

Crushed Eggshells

Crushed eggshells are a natural and slow-release source of calcium. You can add them to the soil before planting or use them as mulch around the base of the plants.

Foliar Sprays

When dealing with severe calcium deficiency or needing a quick calcium boost, try foliar sprays. Mix calcium nitrate or calcium chloride in water as instructed by the manufacturer. 

Spray it on the leaves, making sure to cover them well. Apply the spray during cooler times to prevent leaf burn.

Calcium-Containing Fertilizers

When choosing fertilizers, go for those with calcium as an essential nutrient. These balanced options supply calcium and other needed elements for plant growth. 

Remember to follow the packaging instructions for the right application rates.

Planter’s Tips: To grow healthy tomatoes, keep the soil pH between 6.2 and 6.8. Check and adjust the pH as needed. Proper watering is essential to avoid calcium deficiency. Maintain consistent moisture in the soil, neither too much nor too little. Using mulch around tomato plants helps retain moisture and regulate temperature, indirectly supporting calcium absorption. Avoid fertilizers with high ammonium levels as they can hinder calcium uptake. Be patient when addressing calcium deficiency as it takes time for plants to absorb and utilize added calcium. Monitor progress regularly and adjust as needed for best results.

How Calcium Helps Tomato Plants

How Calcium Helps Tomato Plants
Image by The Farm at Green Village

Calcium plays a vital role in balancing ions and strengthening cell walls. Aside from that, calcium promotes root development and facilitates nutrient transport, among many others. 

Cell Wall Structure and Integrity

Tomato plants require calcium to build robust cell walls. These cell walls act like cement for the pectin molecules in the walls. 

These strong cell walls, in turn, are vital for supporting the plant’s structure. Cellular strength is especially important in areas that grow quickly and bear fruit, like stems and fruits.

Cell Division and Elongation

Tomatoes need calcium for cell division and plant elongation. This results in calcium supporting healthy growth in seedlings and fruit development. 

Nutrient Uptake and Transport

Having calcium encourages balanced and healthy tomato development. The element assists in absorbing and moving nutrients like potassium and magnesium to the right parts of the plant for good growth. 

Enzymatic and Metabolic Activities

Calcium activates enzymes in plant processes. It acts as a strong support for biochemical reactions that end up in better plant health and productivity.

Plant Immune Response

Plants need calcium for defense against pests, diseases, and other stressors. When they’re under attack or stressed, they create a cell wave response. 

This response helps them activate defense mechanisms. As a reaction, they end up producing protective compounds and reinforcing cell walls, all in order to fight against these pathogens.

Fruit Development and Quality

Tomatoes require some calcium during the crucial stages in order to get healthy fruit development. Without enough calcium, they may encounter problems like blossom end rot.

This is a common tomato issue where the bottom of the fruit becomes sunken and discolored. Unfortunately, the affected fruits are beyond rescue.

Post-harvest Shelf Life

Tomatoes with enough calcium last longer after harvest compared to calcium-deficient fruits. Calcium keeps fruits firm and reduces decay during storage and transportation.

Signs of Calcium Deficiency in Tomatoes

Signs of Calcium Deficiency in Tomatoes
Image by Minnetonka Orchards

Tomato plants need calcium to stay healthy. Without calcium, they may face problems like blossom end rot, leaf necrosis, stunted growth, and reduced fruit production. 

Other signs of calcium deficiency include leaf curling, distortion, yellowing of new leaves, poor fruit set, and brittle stems.

Blossom End Rot

Blossom end rot is a typical sign of calcium deficiency in tomatoes. It shows up as dark, water-soaked areas at the bottom of the fruit. 

As it advances, the affected parts may turn black and leathery. This can happen at any stage of fruit development but it’s most common in young fruit.

Leaf Curling and Distortion

Not having enough calcium may lead to young leaves curling. Another indication is the leaves developing unusual shapes. 

Usually, the edges of the leaves tend to look wavy or crinkled. In severe situations, the leaves can become brittle and show signs of necrosis, which is the death of leaf tissue.

Yellowing of New Leaves

You might see new leaves of calcium-deficient tomato plants that look pale green or yellowish. This is because of a condition called chlorosis. 

Chlorosis happens when chlorophyll production, vital for photosynthesis, is disrupted.

Stunted Growth

Tomato plants without enough calcium tend to grow slowly or may even become stunted. This is because calcium is essential for cell division and plant elongation.

Without calcium, the plant gets affected in terms of overall size and development.

Poor Fruit Set and Abortion

Without enough calcium, fruits may not form properly as flowers might drop prematurely. The pollination and fertilization process is also affected.

When this happens, you’ll end up with small or shriveled tomatoes.

Brittle and Weak Stems

Lack of calcium weakens cell walls. As a result, stems end up brittle and easily breakable. 

This is particularly evident during strong winds or when carrying heavy fruit.

Signs of Excess Calcium in Tomatoes

Signs of Excess Calcium in Tomatoes
Image by PlantVillage

Calcium is necessary for tomato plants, but too much can cause nutrient imbalances and toxicity signs. 

Keep an eye out for leaf tip burn, reduced nutrient intake, stunted growth, flower drop, fruit deformities, purpling leaves, poor root development, and alkaline soil.

Leaf Tip Burn

Leaf tip burn is a common sign of excess calcium. You’ll notice brown or necrotic edges on older leaves. 

Sometimes, the leaf margins become crispy or dry, and the affected areas can spread inward toward the leaf midrib.

Reduced Nutrient Uptake

High calcium levels can block the absorption of important nutrients like magnesium and potassium, causing deficiencies. This may result in yellow leaves or interveinal chlorosis, which is the yellowing between veins.

Stunted Growth

High calcium levels can impact nutrient balance in plants, leading to stunted tomato growth with smaller leaves.

Flower Drop and Fruit Deformities

Too much calcium can disturb pollination and fruit formation. It might result in flower drop, where flowers don’t become fruits. 

Also, it can affect the shape and size of the fruits.

Reduced Phosphorus Uptake

Excess calcium hinders phosphorus absorption, a vital nutrient. Signs of phosphorus deficiency might include leaf purpling, especially on the undersides, and weak root growth.

Alkaline Soil pH

Using too much calcium-containing material can increase the soil pH, making it more alkaline. This change in pH impacts nutrient availability, causing imbalances and deficiencies.

Planter’s Tips: In most gardens, excessive calcium in tomato plants is not a common problem. It can happen if you use too much calcium-rich material or fertilizers so be cautious about overapplying them.

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