Pioneering Hydroponics

Since 1976

How Magnesium deficiencies affect your plants

Magnesium deficiencies in plants

How does a magnesium deficiency affect your plants?

Magnesium is an essential secondary macronutrient that is vital for plant growth and health. It plays an important role in the process of photosynthesis and is the key element in chlorophyll, which is required to give leaves their green colour.

As it is an activator for various enzymes, a deficiency will lead to a decrease in enzyme activity which will affect plant growth. It also plays an important role in many other plant functions, such as:

  • Nutrient uptake control
  • Plant oil and fat formation
  • Iron utilisation
  • Transportation of sugars 

Signs of a Magnesium Deficiency

One of the first signs of magnesium deficiency is chlorosis. Chlorosis is the yellowing of the leaf between the veins and around the edges.Chlorosis of leaves

Older leaves becoming yellow at the edges but remaining green in the centre, while the rest of the plant remains unaffected, is a sign of a magnesium deficiency. As magnesium can move freely throughout the plant, chlorophyll in older leaves breaks down and later transports to new leaves.  

If the deficiency is not corrected, it could result in: 

  • Leaf necrosis (death of cells and tissues)
  • Dropping of older leaves
  • Slow growth

Factors to Consider


Your choice of media can affect the absorption of nutrients to your plant. Plants grown in Coco Coir can have difficulty absorbing nutrients such as Magnesium, Calcium and Iron as the Coco can hold onto the nutrients, making them unavailable to your plant.

pH levels

If you’re growing hydroponically, make sure you've got the pH right, as it controls the availability of nutrients to the plant. It should ideally be between 5.8-6.2. If your pH is outside of this range, adding extra nutrients will not fix deficiency and could do further damage.

If you let the pH of the nutrient solutions slip to 5.0 or lower, you are likely to experience magnesium deficiency.


Treating a magnesium deficiency is not difficult if the symptoms are recognised early. A calcium-magnesium supplement can be greatly effective in alleviating symptoms showing up in your plants.

Magne Cal+ regulates nutrient transport, strengthens cells, supports photosynthesis and enzyme processes, prevents and cures magnesium deficiency, which causes yellow leaves and it also boosts the effectiveness of your PK. Alternatively, if you’re growing organically, Organic Magnesium effectively treats and prevents magnesium deficiencies at any point in the grow.

It’s always important to spot a deficiency early to combat the symptoms quickly and efficiently. Understanding the role of magnesium and how it affects your plants is key in maintaining optimum health for your plants!