Cal mag deficiency can be due to improper pH levels, use of poor quality water or insufficient nutrients in the soil that results in limp stems and spotted leaves. Don’t worry, we can help you tackle this problem with quick resolutions.

Cal Mag Deficiency PlantAmerica

In this article, you will find deeper insights into the causes of this deficiency, the symptoms, and ways by which you can restore plant health.

Continue reading to know what is causing it and how to keep your plant in good shape with just a little bit of watchfulness.

Why Is There Cal Mag Deficiency in the Plant?

💥 Quick Answer

Cal-mag deficiency occurs when the garden soil is sandy or coarse and is subject to RO treated water or heavy phosphorus-based fertilizers. Aside from these, there are a few other reasons such as pH imbalance and low transpiration that can cause the problem.


Let us identify each one of the causes and the symptoms they manifest in the below section.

– A Highly Acidic or Alkaline Soil

Highly acidic or alkaline soil is one of the main reasons for calcium and magnesium deficiency. You will notice symptoms in the form of curled leaf edges or dappled leaves with yellow or brown spots.

In acidic soil, the plant will find it difficult to take in calcium and magnesium whereas, in highly alkaline soil, the phosphate ions react with magnesium and calcium making them difficult to be soluble in the soil. However, it is only within the ideal pH range of 6.5 to 7.5 that the plant will thrive with nutrients intact.

– Nutrient Imbalance

If you have been feeding your plant incorrectly, without focusing on its complete nourishment, then there is a strong chance of it developing a calcium magnesium deficiency. Nonetheless, a plant requires the right balance of all nutrients such as sodium, potassium, aluminum, and manganese to sustain itself.

Nutrient Imbalance Plant America

The collective ability of all these compounds binds calcium and magnesium to the plant cells, so an abundance of just one type of nutrient leads to over-saturation and deficiency. Furthermore, in this condition, you will notice stunted or slow growth of root, shoot, and apical buds along with limp stems that have no vigor.

– Low Transpiration Rate

When less water evaporates from leaf and flower pores, the plant is said to have a low transpiration rate. This leads to a deficiency as the plant is unable to efficiently transport nutrients from the root through the shoot. 

The main reason for the low transpiration rate is high humidity, still air, chilly weather, and inadequate watering. Thus, if you are over-exposing your plant to cold weather or growing it in a still environment with excessive moisture, it is most likely going to develop a deficiency.

– Use of Treated Water

Are you watering your plant with distilled or reverse osmosis water? Then this is another strong cause for the plant to develop a deficiency.

Use of Treated Water Plant America

Rainwater and tap water contain essential calcium and magnesium that aid the optimal growth of the plant. Treated reverse osmosis or distilled water is stripped of these thus the plant is deprived of the much-needed nutrient, leading to deficiency. You can read more on how to purify tap water easily at home.

– Using Soft Water

Soft water may surely keep your plant alive; however, it may not be an ideal option. This is because soft water comes with a lower pH with little or no calcium or magnesium. On the other hand, hard water contains a higher concentration of dissolved minerals of calcium that reduce the chances of a deficiency. So, avoid using hard water since it is bad for plants.

– Sandy Coarse Soil

If you are using sandy and coarse soil or coco coir as your planting medium, do note that it contains low levels of calcium and magnesium in comparison to loamy and clayey soils. The higher the clay particles the more are the minerals.

Sandy Coarse Soil Plant America

How To Fix Cal-Mag Deficiency

Now that you have understood the causes and the ways to identify them, let us go deep into finding a solution to the problem. In the below section, we list out options with which you can easily resolve the issue and grow a happy thriving plant.

– Tackle the PH Imbalance

Bring the pH level to the ideal range to ensure the plant remains healthy. You can add in some lime to increase the pH of acidic soil. Additionally use gypsum or bone meal to bring it to the desired level if the soil is way too alkaline. You can always use a testing tool in order to check the pH level before making any alterations to the soil.

– Provide Well-balanced Nourishment

Fertilize the plant’s right to aid in the absorption of calcium and magnesium. Avoid heavy phosphorus-based fertilizers especially in non-flowering plants as this will lead to excessive insoluble calcium in the soil. To restore the right balance, flush the plants with pH neutral water and then apply a well-balanced formula

Provide Well balanced Nourishment Plant America

– Manage Low Transpiration Rate

Plants require saturated moving air around them to increase transpiration and thereby lower the risk of deficiency. Keep the plant in a well-ventilated spot where there is a constant movement of air. Make sure the plant is watered well so that there is enough water for the calcium to travel upwards to the leaf, despite the low transpiration rate.

– Use the Right Water

Tap water, hard water, and rainwater are better options to use in comparison to treated RO, distilled, or soft water. 

– Manage Climatic Conditions

High humidity and temperatures also lead to conditions of deficiencies, thus providing the plant with moderate humidity and heat.

Manage Climatic Conditions Plant America

If indoors, reduce humidity by using a dehumidifier and placing it under diffused partial light. If outdoors protect the plant from exposure to extremes of temperature such as chilly winds and direct afternoon sun.

– Use Pre-mixed Cal-Mag Supplements

You can buy and use a pre-mixed cal-mag supplement from gardening stores or reputed online sites. The pre-mixed supplement comes in varied serving sizes so one that’s recommended for your plant type.

Follow the manufacturer’s instructions for the right application. Apart from using the supplements strive to maintain healthy pH and balance of other nutrients.

– Check Soil Before Adding Supplements

If your plants are showing signs of a deficiency such as less growth or discoloration, before you add in any form of supplement, check the soil. The soil may have adequate levels of calcium and magnesium and the signs may be indicative of something else. 

– Home Made Calcium Magnesium Supplements

Calcium Magnesium Supplements Plant America

It is easy to make a batch of homemade supplements to overcome the deficiency. Mix Epsom salts, which chemically is magnesium sulfate, with calcium nitrate in a ratio of 1: 1.5. This will amount to around 0.15 ounces (4.5 grams) of Epsom salt and 0.2 ounces (6 grams) of calcium nitrate per gallon of water.

Having a slightly higher amount of calcium keeps even older leaves healthy, preventing discoloration and root rot.

– Organic Matter as Supplements

Organic Matter as Supplements Plant America

You can also use the below-mentioned organic matter

  • Calcitic Lime: High in calcium carbonate, it not only adds calcium to the soil but will also raise the pH. This is an ideal option if your soil is acidic and low in pH. So check your pH before applying calcium lime as it may not be of much help if you have high alkaline soil.
  • Dolomitic Lime: This contains calcium carbonate along with magnesium carbonate. Similar to calcitic lime it raises the pH level so use it only after checking your soil.
  • Gypsum: This is a naturally occurring substance with calcium sulfate and will perfectly serve the purpose of supplementing calcium to the plant.
  • Calcium EDTA: A water-soluble form of calcium, EDTA has calcium molecules that do not react with any other elements in the plant-soil and do not leach.

– Home-based organic supplements

Home based organic supplements Plant America

You can easily make your supplement with these easily available home organic matter.

  • Bone Meal: This is a fine powder of crushed bones that is rich in phosphorus and calcium.
  • Crab Meal: This product is again a fine powder of crabs and crustaceans that can supply the plant with 10 percent to 20 percent calcium.
  • Eggshells: Powdered eggshells are an excellent source of calcium carbonate, especially for indoor plants.

– Monitor Your Plants

Regularly monitor your plant by testing the soil for calcium and magnesium. This is a preventive measure and will go a long way in keeping the plant foliage healthy.

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