How to Fix Calcium Deficiency in Plants

When you see your plants struggling from slow growth, it could be a lack of calcium, and that means you need to know how to fix calcium deficiency in your plants. Your plants will soon become weaker and stunted if this nutrient shortage is not addressed immediately.

Of course, calcium deficiency involves a lack of this nutrient in plants…but solving this issue isn’t as simple as adding more of this plant nutrient to your soil or solution. We’re going to cover the nuances involved in addressing this shortage and putting your plants back on track to vigorous growth and high yields.

What is Calcium’s Role in Plants?

What is the role of calcium in plant health? After all, it’s not even a primary nutrient.

While plants don’t need as much calcium as they do nitrogen, phosphorus, and potassium, they require more calcium than they do micronutrients. Without enough of this vital nutrient, you’ll notice that plant growth is limited.

Calcium deficiency can cause your plants to lose both their structural and communicative functions.

Structural Functions

Calcium is an essential component of both cell walls and cell membranes.

If a plant is lacking this nutrient, cell walls will be less rigid and you’ll notice it. The unusual growth of new leaves and root tips can cause discoloration or curling. In extreme cases, meristems might even die back.

In cell membranes, calcium binds to phospholipids which increases stabilization. If a plant doesn’t have enough calcium, the permeability of the membrane rises which leads to necessary ions and compounds escaping cells.

Signaling Functions

Without calcium, plants have a hard time receiving messages regarding stressors and developmental processes. When plants lack calcium, you’ll notice a serious decline in their overall health.

Plants can often defend themselves when pests and diseases attack, but they must know they need to do so! Calcium is a crucial part of the chain that tells a plant it needs to protect itself. While this nutrient doesn’t directly fight against these enemies, it is a crucial component in the line of defense. If calcium is lacking, plants are more likely to experience serious damage.

Calcium It also regulates the movement and distribution of nutrients within a plant. While calcium is immobile, it helps tell the plant when mobile nutrients such as nitrogen, potassium, and iron are needed in certain tissues.

What Causes Calcium Deficiency?

Calcium deficiency could be thought to be caused by calcium deficiency. While this is true, it doesn’t tell the whole story. Just because there’s enough calcium in your soil or solution doesn’t mean your plants will have all the calcium they need. Calcium deficiency can be affected by the following factors:


The pH largely impacts the availability of calcium. The pH of the soil or solution will affect how easy it is for plants to absorb this essential nutrient.

Nutrient Balance

Calcium is a cation aka a positively charged ion. Its positive charge binds to negatively-charged sites on clay and organic matter particles.

Cation exchange capability, or CEC, might be something you’ve heard. This refers to the ability of soil or other material to hold cations. Clay and organic matter are high in CEC, while sand is low.

But, calcium isn’t the only element that binds to these sites.

Magnesium, sodium, potassium, aluminum, and manganese all bind to negatively charged sites, and an overabundance of one nutrient can lead to over-saturation. If you add ten times as much magnesium to a plant, it will fill a lot of the exchange sites. If you add calcium, it won’t have anything to hold it, so it may leach out of your soil or substrate.

Transpiration Rate

If you need a refresher, transpiration is when water evaporates from plant tissue such as leaves and flowers. Although plants absorb a lot of water from their roots, most of the water is recycled back into the atmosphere by transpiration.

How does this relate to calcium?

Calcium The xylem is more important than the phloem for moving water through a plant’s body. Remember that phloem are living cells that transport plant sap in multiple directions, while xylem are dead cells that transport water upward.

Since calcium can only move throughout a plant in the xylem, its movement is closely linked to transpiration rates. When water evaporates from plant tissue, sucction action draws more water upwards.

Low transpiration rates are a common cause of calcium deficiency in plants since decreased evaporation leads to decreased movement of water — and calcium — through the xylem. Low rates of transpiration can be caused by low water levels, low humidity, and cold temperatures. This a probably a good time to read up on Vapor Pressure Deficit (VPD) to make sure you know how to keep your humidity balanced with your temperatures.

Calcium Deficiency Symptoms in Plants

Calcium is an immobile nutrient, so once it makes its way to a part of a plant it’s there to stay. If a new leaf forms and it needs calcium, older leaves can’t send any of this cation its way. That means that calcium deficiency symptoms occur in new growth before they show up in older plant tissue.

While symptoms may vary depending on the plant, there are some common themes among all species. If you spot any of the following symptoms, it’s likely that a calcium deficiency is to blame for your plant’s problems.

As a plant begins to lack calcium, new leaves start to curl at the edges. Yellow or brown spots along the edges of leaf leaves are another sign of calcium deficiencies. The yellow or brown spots can eventually spread to the entire leaf. These spots can easily be mistakenly thought to be nutrient burning.

The growth of tip tissue (or shoot) is also affected by a lack of calcium, causing both root and shoot tips to experience dieback. While you’ll be able to spot issues with the shoots, you would have to dig up the plant to see its roots. Since this is out of the question, know that root dieback can present itself as a general decline in plant vigor.

How to fix calcium deficiency in plants
You will notice the curling leaves and brown apical meridium.

Bloom end rot can occur in fruiting crops if there is a deficiency of calcium. This phenomenon is noted by a soft, rotting fruit tissue in crops including tomatoes, peppers, and melons.

The last symptom is a general lack in vigor. Low calcium can indicate poor communication because calcium is essential for plant communication. And we all know that things take a turn for the worse when everyone isn’t on the same page. So if you notice your plant looks like it’s health is declining, it’s a good idea to check out calcium levels.

Do My Plants Have a Cal Mag Deficiency?

Sometimes you’ll hear growers say that they’re plants are lacking cal-mag, or calcium and magnesium. Since these nutrients are both cations, they are sometimes held by soil or media and left unavailable to plants.

While it is possible that plants are lacking in both of these nutrients, you can have a calicum deficiency but not a magnesium deficiency. This is actually quite common.

The deficiency symptoms of these two elements can appear similar for someone who doesn’ know what they’re looking for. The truth is, these nutrients have very different deficiencies.

First off, magnesium is a mobile nutrient, so symptoms first occur in older tissue. As you learned above, calcium is immobile, so symptoms will show up in a young leaf before they do in an older leaf. Although both nutrients can affect the color of tissue, there is a subtle difference. Insufficient calcium can cause yellow or brown spots, and too much magnesium can result in a yellow-colored leaf with deep-green veins.

You should inspect your plants and make sure you only provide the nutrients they need. You can also submit a tissue sample for analysis if you’re unsure what nutrients your plant needs.

Sources Of Calcium For Plants

Learning about the many different calcium-containing products will help you learn how to fix calcium deficiency in plants.

Calcitic Lime

Calcitic lime is largely composed of limestone high in calcium carbonate (CaCO₃). This material is often used to raise soil pH, as the carbonate reacts with hydrogen ions to neutralize the soil. Lime also adds calcium to the soil, but it’s important to take its effect on pH into account before applying.

Dolomitic Lime

Just like calcitic lime, this material contains calcium carbonate, but it also contains magnesium carbonate (MgCO₃). This means it raises pH, and supplies calcium as well as magnesium.


Also known as calcium sulfate, gypsum is a naturally occurring mineral that contains calcium and sulfur.

Bone Meal

Bone meal is a fine powder made from crushed bones. It provides plants with phosphorus as well as anywhere between 15 to 25% calcium depending on the product.

Crab Meal

Made from the shells of crabs and other crustaceans, this product supplies plants with nitrogen, phosphorus, and calcium. Crab meal can contain between 10-20% calcium, depending on which brand it is.

Calcium EDTA

This is a chelated form of calcium that is water soluble. EDTA holds onto calcium molecules so they don’t leach out of solution or react with other elements to form compounds that are unavailable to plants.

Water Soluble Calcium for Plants

Different forms of calcium have varying levels of water solubility, and various factors impact the solubility for each product. For example, gypsum’s solubility is affected by water temperature, particle size, and soil properties.

How to Fix Stunted Growth Due to Calcium Deficiency in Plants

If your plants are exhibiting signs of calcium deficiency, don’t just dump more calcium onto them! It’s quite possible that your soil or solution has an adequate level of calcium but this nutrient isn’t making its way into your plants. In order to learn how to fix calcium deficiency in plants, you’ll need to learn the reasons why this nutrient might not be making it into your plants.

If you think there’s enough calcium in your soil or solution, but your plants are telling you that they need more of this essential nutrient, take a look at the following.


If plants don’t have access to water, they won’t have access to calcium. Drought stressed plants are often deficient in calcium, so make sure you’re providing enough water.


If your pH is too low, plants will not be able to take up calcium you add. If your pH is lower than 6.0, raise the pH before you attempt to fix any calcium deficiencies.


As we’ve said above, calcium in plants is linked to transpiration rates. Low temperatures in your outdoor garden or grow room will cause low transpiration rates and consequently a shortage of calcium.

Humidity and Airflow

High humidity and poor airflow can also lead to low transpiration rates. If you plants are sitting in humid and stagnant air, add in some fans to increase transpiration rates. Check your Vapor Pressure Deficit (VPD) level.

If all these factors seem in line with proper calcium uptake, you might need to add fertilizer to your soil or solution.

How to Put Calcium in Soil

Before you add any nutrients, including calcium, it’s wise to conduct a soil test. This will tell you how many nutrients are in your soil already as well as what to add.

If your soil is deficient in calcium, you can add this nutrient using various products. Your soil pH will play a major role in the choice of product.

If your pH is more than slightly acidic (with a pH below 6.0), it’s best to add calcium via lime, since this will raise the pH. If the soil pH is already at a desirable level, choose a product that doesn’t impact the pH, such as gypsum or bone meal.

Be aware that these products may contain other nutrients. Before you apply a product to your soil, see if you’ll be creating an excess of some other nutrient.

How to Put Calcium in Solution

When you’re adding calcium to a nutrient solution, pay attention to the water you’re starting with. Hard water is high in dissolved minerals including calcium, so you won’t need to add as much calcium to hard water.

EDTA calcium, like Greenhouse Feeding Calcium, adds only calcium to solution, so you can add just the amount of calcium you need without over-applying other nutrients. This is also an extremely stable form of the nutrient, so there’s no need to worry about the calcium interacting with other nutrients or precipitating out of solution.

This form of calcium can also be absorbed easily by plants because it is highly soluble. You don’t have to worry about applying calcium only to see it become unavailable to plants.

Just like with other nutrients, it’s helpful to use a nutrient feeding chart to calculate how much calcium you need to add during various stages of your plant’s growth cycle.

Now You Know How to Fix Calcium Deficiency in Plants

Now that you know all about calcium, you realize how important it is to fix any deficiencies! If you optimize your environment and choose soluble calcium sources, you can help plants recover from the detrimental effects of low calcium.


Applying Lime to Raise Soil pH for Crop Production

Calcium — Nutrient and Messenger

Calcium: A Central Regulator of Plant Growth and Development

Cations and Calcium Exchange Capacity

Calcium in Plants


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