The yellow leaves they highlight a problem with the plant and allow us to intervene, in this sense they are a positive fact because they represent an indicator of the state of health. However, it is necessary to trace the real causes of yellowing, which is not always easy.
The most common cause of yellow leaves it is a deficiency of iron in the soil. Iron, together with magnesium, is one of the main constituents of the chlorophyll molecule and helps regulate some important processes in plant life, including respiration.
If the yellow leaves are due to an iron deficiency the problem is a ferric chlorosis, a fairly serious problem but solvable. In a ferric chlorosis the leaves initially tend to yellow over the whole page except for the veins, where the chlorophyll is concentrated. This is followed by a progressive weakening of the plant, the progress of yellowing and the fall of the leaves. If no action is taken in time, the plant dies.
The remedy consists in compensating for the iron deficiency when the first appear yellow leaves, which usually sun younger and weaker. Iron-based compounds are very common and are easily found in gardening shops, agricultural consortia or by taking advantage of online shopping.
The “chelated iron” fertilizers are administered by burying them in the ground quickly because the light tends to degrade this particular fertilizer. The chemical composition of these compounds makes iron available even in calcareous soils, i.e. those soils responsible for iron chlorosis, the disease underlyingyellow leaves.
To understand what iron-based fertilizers are, we invite you to visit the dedicated Amazon page: fertilizer based on chelated iron.
If the lack of iron in the soil is a known fact, it can be acted in the autumn during the digging of the soil by adding a correct dose of iron. Then continue in the spring with a foliar fertilizer. The yellow leaves will tell us if and how much action is needed.
Yellow leaves from the cold
Warning: yellowing of the leaves is not always caused by an iron deficiency.
It could also be that the plant has caught cold or has been in the middle of drafts. Once this has been verified, it may be sufficient to move the pot if it is a houseplant or to temporarily cover it if it is in the garden.
Other causes of yellow leaves.
The yellowing could also depend on a magnesium deficiency, but the difference is that in this case the leaf tends to fade in the central part and remain green at the bottom towards the root. Once the problem has been ascertained, in this case too the remedy consists in compensating for the lack of the chemical element.