Magnesium is a vital nutrient contributing to healthier plants with improved growth. It is an essential component of chlorophyll, and its deficiency causes the degradation of chlorophyll. – Gro Indoor
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How Magnesium Regulates a Plant's Health and Impacts Its Growth

by 09 Apr 2023

How Magnesium Regulates a Plant's Health and Impacts Its Growth

When we talk about human beings and their nutrition, the first thing that we envision is food. If we see someone malnourished or underweight, the first suggestion that we come up with is to have a balanced diet. We call it a balanced diet because it contains macro and micronutrients. The micronutrients for humans are minerals, vitamins, and fiber. Plants comprise a significant portion of our food, but we can only read their benefits if the plants are free of diseases and are growing well. Human needs certain nutrients to grow and stay healthy; similarly, plants also require nutrients essential for their growth and health.

Magnesium is one of the macronutrients out of the 17 necessary nutrients required for plants. It is an abundant mineral found in soil and holds substantial importance for a plant's health and growth. Out of the three secondary nutrients necessary for plants, magnesium is one of them; the other two are calcium and sulfur. The term secondary refers to the mineral's quantity; it is as important as those key nutrients. A lack of any secondary nutrient can be as detrimental as any key nutrient. Many new growers are unaware of the benefits and significance of magnesium in the plant's health. They focus more on key nutrients like nitrogen, phosphorus, and potassium.

If you are a new grower, you will find many experienced growers swearing by their Cal-mag supplement. One might question why they are swearing at it so much. We know that plants cannot survive without photosynthesis, nor can they survive without chlorophyll regulating the process.

You will find many growers swearing on Cal-mag supplements because magnesium is another core mineral responsible for photosynthesis. Vital secondary nutrients are equally important for both indoor and outdoor plants. If you are a new grower and you have plenty of questions about understanding nutrient management in plants, this article will serve you as a guide. We intend to explore magnesium's impact on a plant's growth and health, its resources, and how to combat its toxicity.

The Significance of Magnesium for Plants

Plants can only grow well and healthy if they are getting all the essential nutrients required. Magnesium being a secondary nutrient, play a substantial role in regulating its health and growth. It also mediates photosynthesis by helping the chlorophyll convert light energy into usable energy. It is an optimal nutrient for not only plants but chlorophyll. The green colors of plants stem from chlorophyll, which helps them convert light energy into sugars, enzymes, and carbohydrates, facilitating growth. It also assists in the transportation of phosphorus, which is a key nutrient for plant growth.

When transported to the desired areas, phosphorus initiates phosphate metabolism, stabilizes the cell membrane, and metabolizes carbohydrates. Magnesium aids in transporting the key nutrients to maintain the various functions happening inside a plant. Besides transporting key elements like phosphorus, it also enables iron transport and helps the fruit to reach full maturity.

Sources of Magnesium for Plants

If you plan to grow healthy plants and want fertile land, you can add magnesium to the soil or its substrate before planting. Applying compost (annually) can help the soil retain moisture and a little bit of texture easily. A well-structured soil can resist erosion, and it also holds nutrients in it. Using a chemical spray on leaves also provides readily available magnesium or sprinkling some Epsom salt can compensate for your plant's need for magnesium. Chemical spray and Epsom salt help plants uptake nutrients and improve magnesium's quantity in nutrients deficit soil.

Choose Cal-Mag Supplement

Plants are usually deficient in both Calcium and Magnesium. Many growers who are growing on a large scale choose Cal-Mag supplements to meet nutrient requirements. This supplement is useful for hydroponics and soil-based plants. Plants growing in high humidity and temperature often go scarce in Calcium and Magnesium.

If you notice the yellowing of veins in the leaves and if they appear to have a marbled structure, this points towards a magnesium deficiency in your plant. Cal-Mag supplement is the go-to option of many growers for stabilizing the plant's growth and health to overcome this deficiency.

Effect of pH on Magnesium Absorption

Magnesium is a metallic element meaning that it is prone to the reaction of different ranges. Suppose you are adding magnesium to the soil; it is always better to check your soil pH. Our goal is to help the plant meets its nutrient requirements, not to drain it further. Suppose the soil's pH is less than 7.0. In that case, magnesium will become readily available for absorption, adding magnesium to soil or a soil-less setup. In the case of acidic pH, the magnesium absorption will slow down, and your efforts will go down the drain. Testing soil pH is vital to facilitate nutrient absorption by roots before adding the deficient nutrient.

What are the Signs of Magnesium Deficiency?

If you have planted your plants in sandy plants, there are higher nutrient drainage chances, leaving nothing behind plants. Magnesium deficiency in plants is one of the common deficiencies that many growers face. Multiple reasons can lead to this nutrient deficiency, but it is fixable.

One of the reasons why it occurs is that the soil you are using is either not organic or lacks enough nutrients. Heavy rainfalls also contribute to leaching magnesium from the soil. Other common causes of magnesium involve wet, cold, and acidic environments. Reduced evaporation, limited root system, or external stress on the plant can also lead to magnesium deficiency.

Magnesium is a mobile nutrient, and it can move easily in plants. Whenever a plant goes deficient in magnesium, the effect will start appearing in the younger leaves first. Unlike the primary nutrients, magnesium deficiency targets fresh or young leaves compared to older ones. As a result of this deficiency, the young plants appear brownish or red, or they might undergo chlorosis, worsening chlorophyll's presence.

A minor deficiency of magnesium will not affect the plant. I can leave detrimental effects on mature plants in severe deficiency cases, leaving them unable to bear fruits. Unlike other nutrient deficiencies, magnesium deficiency keeps getting worse unless you address it. The following are the different stages that might occur during its deficiency.

Progression of Magnesium Deficiency in Plants

When a plant is a magnesium deficit, the onset of symptoms does not appear instantly. You might notice any variation at all in the first few weeks. As the plant reaches five or six weeks, the necrosis becomes evident on the middle-aged leaves.

There appear rusty brown patches, and their number and size increase over the leaves, leaving the leaves yellowish. The symptoms keep getting severe over time, and the intensity increases. The leaves begin to fall off, younger leaves also endure the deficiency, and the plant's overall health takes adverse turns. After confirming the magnesium deficiency in plants, check for the temperature, pH, humidity, and electrical conductivity (EC) of the substrates and soil.

How to Identify Magnesium Deficiency?

Once you have identified the causes leading to magnesium deficiency, the next question is to identify deficiency symptoms. It is easily identifiable by examining the plant leaves. When plant roots cannot absorb sufficient magnesium from the soil, the older leaves will be the first to endure the effect as they are nearer to roosts.

The chlorophyll starts to degrade in the older leave, making them lose their green coloration. The degradation of chlorophyll is known as chlorosis. The leaves start appearing yellow, yellow-white, or pale. There is an evident marbled strip appearance in between the veins depicting the magnesium deficiencies. The other signs that can give you a heads-up about magnesium deficiency are the curling of leaves, necrosis, and yellowing of older leaves in between veins.

The leaves in the image depict the signs of magnesium deficiency. The image on the left shows the chlorosis in the older leaf, and the image on the right has a marbled stripe appearance in between veins. Magnesium can easily move to the areas where the plant needs it. When the older leaves start getting deficient in magnesium, the plant starts chlorosis in those leaves to break down magnesium and supply it to its younger leaves.

Measures to Treat Deficiency

We have identified the causes and the signs to confirm that plants face magnesium deficiency; the next step shall be to treat or at least take measures to stop it. Using mulch and organic compost tea is one way to treat plants with magnesium deficiency. Compost tea contains magnesium; when we apply these solutions to plants, the roots quickly soak up the magnesium to combat the deficiency. Another way that gardeners or growers use to treat magnesium deficiency is through Epsom salt use.

One of the most operative ways to treat magnesium deficiency is to spray Epsom salt on your plants. Using synthetic plant nutrients to neutralize or balance magnesium levels can also prove fruitful. Recheck the stability of all the conditions that can help in preventing magnesium deficiency. Maintaining the pot temperatures and keeping things dry also helps in combating deficiency.

To create Epsom spray, all you need to do is dilute Epsom using 2tsp per gallon of water and apply it to your plants. Apply the solution to roots and spray at foliar. To obtain an excellent result, use 2% of Epsom solution as spray until all deficiency signs disappear.

Another way to overcome magnesium deficiency is to use a dolomite limestone solution. Dolomite limestone has calcium and magnesium in its composition and has the same benefits as Epsom salt. Adjusting the pH range between 5.5 or above in the hydroponic system and 6.5 or above for soil-based plants facilitates nutrient absorption that may slow down due to pH imbalance. Also, reducing the EC for a week improves nutrient absorption.

Magnesium deficiency often points out other nutrient deficiencies that a plant may face. Gardeners and growers keep the Cal-Mag supplement handy if they need to treat any other nutrient-related deficiency. All-in-one combined solutions provide the necessary nutrients that a plant may need. Doing so boosts foliage growth and results in healthier fruits and blooms.

What is Magnesium Toxicity?

If a plant is getting insufficient nutrients, it turns into nutrient deficiency, but if your plant is getting way more nutrients than it needs, it turns into nutrient toxicity. Magnesium toxicity in plants is rare, and it is almost impossible to see it with the naked eye. In extreme cases, the overfeeding of magnesium interferes with other nutrients like calcium. It happens more commonly in hydroponic systems. Toxic build-up in the soil is uncommon.

By now, we know the symptoms of deficiency, how to monitor the symptoms, and the benefits of monitoring magnesium content in your soil or a hydroponic system. Are you still looking to learn more about the signs and symptoms of other nutrients? Our nutrient deficiency series of copper, phosphorous, and manganese can be your go-to option to find the answers you need.

Further, if you want to learn more on plant nutrient toxicity and ways to fix it, read on: How to Fix Plant Nutrient Toxicity to know in details.


Plants are appealing and add beauty to our gardens, but they can also be tricky to handle. With an imbalance of nutrients, plants can't yield a better product or even survive. You may not find much discussion on magnesium compared to other nutrients; it does not mean that it is inessential or contributes to the plant's health.

Understand magnesium's role in your plants, learn about the signs of deficiency and toxicity, and know about the methods you can use to treat these issues. Further, experts at are one call away to help you. Contact us at 866-GRO-INDR.

Sep 14th 2022
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