Is Magnesium Fertilizer Healthy For Plants?

Last updated on October 23rd, 2023 at 08:52 pm

A magnesium fertilizer supports your plants and the lawn regains its old strength. Because although magnesium is actually abundant in the earth’s crust, soils are not exactly blessed with much magnesium. The reason for this is crop deprivation and leaching through rain. If you notice a high pH level in the soil, you can also use a fertilizer that provides lawn lime in addition to the magnesium.

However, if you would like to restore a healthy amount of magnesium to your soil, magnesium fertilizer is a good option.

Is Magnesium Fertilizer Healthy For Plants?

Here you can learn which fertilizers with magnesium are suitable for your soil and how to apply them.


Why the soil needs magnesium

There are a number of important plant nutrients for plant health. These include nitrogen, phosphorus and potassium as well as magnesium. Magnesium is needed for plants to build chlorophyll. Without the important chlorophyll, the plant cannot use the energy of the sun in the form of photosynthesis and would die after a short time. This already shows that magnesium is one of the essential nutrients and is jointly responsible for the survival of plants.

In the soil, magnesium usually already occurs naturally and you do not necessarily need to use an additional fertilizer. However, the content of magnesium is highly dependent on the pH and the substrate.

On light, sandy and acidic soils, magnesium is rather scarce. Acidic soils in particular are therefore a great challenge for your plants and you should get this under control with the lawn lime already mentioned.

Another reason why the magnesium in the garden soil is no longer so common is due to precipitation. These wash the magnesium right out of the soil and in this way four to eight grams of magnesium per square meter can be driven away annually. This means that magnesium is regularly removed from the soil, but not added, which is why a magnesium deficiency will occur after a certain period of time.

If you have seeded the lawn, then in the growing season the need for magnesium is highest. The plants need a lot of nutrients now to become strong and grow in height. Also in the dry period, when the plants do not have enough water available, they make increased use of magnesium.

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Potassium fertilizers, which are applied for example in the form of a liquid fertilizer, are already more common in the garden. Potassium is considered a counterpart to magnesium and if the soil is too rich in potassium, then this can affect the absorption of magnesium.

How to recognize magnesium deficiency

Magnesium is a plant nutrient responsible for the formation of the important chlorophyll, or leaf green. Leafy greens are directly involved in the process of photosynthesis and when magnesium deficiency is present, it results in severe damage to plants.

First, however, you should know that plants are true survivors. If there is a magnesium deficiency, the plants themselves can take measures to control the magnesium balance.

In order to continue to build up young leaves and shoots, magnesium is transported from the older leaves to the young leaves. Overall, however, the magnesium concentration in the leaf interstices decreases.

You can recognize this by the fact that a lightening of the leaves takes place. This is also known as chlorosis and is the first warning sign that a magnesium deficiency is present.

As it progresses, changes will be most noticeable on the older leaves. This is because the plants concentrate the magnesium more in the young shoots and leaves. This leads to a lightening of the leaves, first of the old leaves and then also of the younger leaves. It is noticeable that the leaf veins continue to have a strong greenish color and stand out visually.

In addition to the coloration of the leaves, you will also be able to recognize that the plants absorb water and other nutrients only to a reduced extent.

Leaf fertilization

If you recognize the first symptoms of magnesium deficiency, then you should not hesitate and supply your plants with the required nutrients again. Otherwise, the plant will only suffer unnecessarily and the older leaves will die irretrievably.

Normally, fertilization takes place in the soil. There, the nutrients are absorbed at the soil through the roots and processed by the plant.

In the case of acute magnesium deficiency, however, absorption via the roots takes too long. In addition, the weakened plant already has problems absorbing nutrients through the roots.

As a solution, you should use foliar fertilization. In this case, the nutrients are applied directly to the leaves of the plant and absorbed by diffusion. However, this is not quite so simple with magnesium. This is because magnesium is not insoluble in water and therefore not exactly suitable for diffusion.

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Therefore, you should use a magnesium fertilizer that is specifically suitable for foliar fertilization. Here the magnesium is dissolved in salts, which are absorbed by the leaf by osmosis.

For better effectiveness, it is advisable to keep the plant generally somewhat moister. When applying, you must also remember that the risk of burns is very high due to the high salt content. Therefore, you should apply this magnesium fertilizer only in the evening. This also ensures that the fertilizer does not evaporate and the leaves can absorb the full amount of nutrients.

Carry out a soil test

If you are unsure whether the level of magnesium in the soil is sufficient and the reason for the discoloration of the leaves, a soil test can provide clarity. During the soil test, the magnesium content in the soil is determined.

If the soil analysis shows that there is too little magnesium in the soil, you can fertilize it yourself with magnesium sulfate. For the soil analysis you have to take the soil from your garden and send it to the Chamber of Agriculture or a research institute, if they offer such an analysis. The garden center can also perform such an analysis for you in special cases. However, such an analysis takes a long time and by the time you receive the results, it may already be too late for your plants.

If you do not want to invest the cost in a professional soil test, then you can also determine the pH value yourself. For this purpose, there are simple soil testers that you can purchase online. These are equipped with the soil from your garden and some distilled water. Within a minute you will already get the result.

If the pH value indicates that the soil is acidic, you should immediately start applying the magnesium fertilizer.

Apply magnesium fertilizer

If you have carried out foliar fertilization and are now looking for a more long-term solution, then you should apply the magnesium fertilizer for the soil.

You should repeat this at regular intervals each season, as it is heavily stressed by the growth of plants and rain.

For optimal fertilization, you can use Epsom salt. In case of acute deficiency, it is recommended to apply about 100 to 200 grams per square meter.

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In the long term, you can then fertilize every year with 50 to 100 grams of Epsom salt per square meter to keep the amount of magnesium in the soil sufficiently high. If there are no longer any signs of deficiency, you can also use a simple complete fertilizer that contains other nutrients in addition to magnesium. This will keep the soil well supplied for the entire season and allow the plants to grow ideally.


Are your plants’ leaves turning yellow and you’re not absorbing the water and nutrients as well? Are they growing more slowly, but the leaf veins are still very greenish?

If so, there is most likely a magnesium deficiency in your soil. The magnesium deficiency can be due to rain leaching or unfavorable soil conditions.

In an initial measure, you should apply magnesium in the form of a foliar fertilizer. After that, it is recommended that you apply Epsom salt to your soil.

To check if the soil is generally too acidic and this is a reason for the magnesium deficiency, you can buy a soil tester online yourself and check the soil of your garden for the pH level.

So, if your plants look a bit sickly, then consider if there is a magnesium deficiency and take the right countermeasures. With the magnesium fertilizer you provide again for strong green and healthy plants in your garden.


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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