Does my plant have an iron deficiency?

Whether you’re a beginning or an experienced cultivator, you will be confronted at some point with a plant deficiency.


Whether you’re a beginning or an experienced cultivator, you will be confronted at some point with a plant deficiency. In this case an iron deficiency, a shortage in iron is often mistaken by other kinds of deficiencies or diseases. We will tell you how to recognise it, why it’s important and how you can solve this problem.

Iron deficiency: how do you recognize an iron deficiency in your plant?

An iron deficiency in plants is easy to recognize due to the green-yellow discolouration of especially the young leaves and shoots at the top of the plant. The veins usually stay green. As the iron deficiency persists, the yellowing of the leaves expands and the larger leaves become yellow and eventually white. An iron deficiency in all cases inhibits the growth of the plant.

The yellowing of the leaves is caused by chlorosis, a process in which the plant is not able to absorb iron due to a too high pH, ​​so that less chlorophyll is produced.

Since iron deficiency is often confused with other nutritional deficiencies, it is important to be certain that the symptoms are interpreted correctly. Read for this How do you recognize the symptoms of an iron deficiency?

What is the function of iron for the plant?

Iron fulfils a key role in the metabolism of the plant and is a vital element for plants. For the plant it performs a number of important functions in the total metabolism and iron is essential for the production of chlorophyll, the plant substance that gives the plant its green colour. In addition, it is a so-called co-factor, which takes care of multiple processes.

Iron is a very common element on earth and is even the fourth most common element. In many forms of landscape you can see that the soil is coloured reddish-brown by the presence of iron in the soil that oxidises under the influence of contact with oxygen.

In general, iron is more difficult to absorb for the plant and only in specific forms and under the right conditions it can be properly absorbed by the plant. Many growers assume that when there is iron in the substrate, this is sufficient to prevent an iron deficiency. The issue is that this iron must be in a chelated form in order to be properly absorbed. This absorption of iron is highly dependent on the pH of the substrate. In acidic soils, so with a lower pH value, normally sufficient absorbable iron is present.


How do you recognize the symptoms of an iron deficiency?

An iron deficiency in plants is often misdiagnosed and confused with a calcium deficiency, magnesium deficiency or manganese deficiency. Only paying attention to yellow leaves is not enough. It is important to be able to recognize the different symptoms of an iron deficiency in order to be able to make the correct diagnosis.

A shortage of iron is visible first in the upper part of the plant. The yellowed leaves are mainly under the youngest leaves and shoots. To place it in perspective: a magnesium deficiency manifests itself mainly with yellow leaves halfway and underneath the plant. Characteristic of the iron deficiency is that the veins remain green.

Another symptom of an iron deficiency in plants is an inhibition of growth, which can have major consequences for the harvest of, for example, tomatoes that will remain considerably smaller in size. In case of a serious iron deficiency, branches can even collapse (die-back).

Causes of a deficiency of iron

The causes of iron deficiency in plants are often found in the substrate on which the plant is grown. A calcium rich and alkaline soil (pH> 6.5) is often a cause of iron deficiency in plants. With a combination of sprinkling and adding peat the acidity can be influenced and the pH can be reduced.

A low root temperature can also be a cause of a deficiency. Due to the lower temperature in the root environment, the metabolism is slower and less iron is absorbed.

An excess of copper, manganese and zinc in the substrate can also be a cause of an iron shortage. It is all about balance between the various factors that influence the growth and flowering of the plant. By using high quality plant nutrition you are assured that you have the minimum risk of nutritional deficiencies.

When the grow medium is too wet, there is insufficient oxygen available for the roots. This creates an increased risk of root rot, which causes the root system to function less due to the damaged or dead roots.

When using a nutrient tank, too much light on the nutrient water can cause the growth of algae in the water. The algae also use iron, so there is less available for the plants.

What can you do about an iron deficiency?

An iron deficiency in the initial stage can be reasonably controlled. The deficit can usually be made reversible based on the causes.

  • The pH can be lowered by the addition of peat if you are growing on a coco or soil substrate.
  • The excessive manganese or zinc fertilization can be solved either by lowering it or by adding iron chelate to the substrate.
  • The sprinkling of the substrate must be adjusted in such a way that sufficient oxygen is available for the roots of the plant. The choice for an airy substrate such as High Porosity Cocos can offer a solution.
  • The temperature of the soil should remain stable and reasonably warm, between 18 and 22 degrees. A cold temperature slows down the metabolism.
  • The administration of iron chelates via aquaponics can reduce any iron deficiency. This is also called foliar feeding and this way is seen as the most effective one, since the absorption is more efficient than through the roots.

By spraying the plant with a solution of EDDHA (max. 0.1 gram per litre of water), you often see a reduction of the chlorosis in the affected leaves within 2 to 4 days. EDDHA is a stable iron chelate that is suitable for pH values ​​above 6.5. Spray the leaves in the dark, since the iron chelates are broken down under the influence of daylight and therefore can be reduced for the plant.

Preventing an iron deficiency

Many growers get the scissors to cut the yellowed leaves from the plant. Of course this is symptom relief while the causes could be prevented. Prevention is of course better than cure. By choosing the right substrate and quality plant nutrition, you’ve already come a long in preventing your plants from iron deficiency. During the growth phase you could use a B’cuzz Booster Uni (soil, coco or hydro). If you’re already further in the growing process, e.g. the flowering phase you can choose for ATA Bloombastic or ATA NRG Bi-Bloombastic to give your crop that extra iron boost!