Yellow leaves on hydrangeas: cause & control

Yellow leaves on hydrangeas indicate an iron deficiency. We show how you can recognize the so-called chlorosis and fight it successfully.

When the leaves of your hydrangea (Hydrangea) turn yellow, the cause may be an iron deficiency, also known as chlorosis. Such chlorosis is particularly common in hydrangeas. The reason for this is usually a lack of nutrients. This deficiency leads to bottlenecks in the leaves, which means that no new chlorophyll can be produced. However, the green dye is needed for photosynthesis and is essential for the survival of every plant. The cause of the bleaching problem should therefore be eliminated quickly. In the following, you will learn how to tell whether the yellow leaves on the hydrangea are really chlorosis. In addition to information on successfully combating iron deficiency, you will also find tips on how to prevent chlorosis in hydrangeas.

Recognize chlorosis in hydrangeas

With a hydrangea, the symptoms usually look the same, regardless of whether the plant is in a tub or in a bed. The young leaves first turn yellow, although the thick leaf veins often remain green. If the chlorosis is left untreated, it can continue to spread.

Prevent chlorosis on hydrangeas

The missing nutrient in hydrangeas is almost exclusively iron, although there is almost always enough of it in the natural soil. The reason for the deficiency is not the lack of iron in the soil, but that the hydrangea cannot absorb the iron present. This occurs in hydrangeas when the pH is too high. The bog plant is adapted to low pH values ​​around 4 - 5.5. It should be noted that the different colors of the hydrangea flower also depend on the pH value. The blue hydrangea, for example, needs a pH value of 4 - 4.5 in order to be able to absorb enough aluminum for the blue flower. More information about the Blue coloring of hydrangeas you can find out in this special article.

We at Plantura recommend the following products for hydrangeas:

• Floragard Endless Summer hydrangea soil pink & white: Special soil for healthy and strong hydrangeas. The clay granules improve air and water circulation.
• Floragard Endless Summer hydrangea soil blue: Special soil for healthy and strong hydrangeas. The strong, bright blue bloom is preserved in the long term by using aluminum fertilizers. The clay granules improve air and water circulation.
• Floragard compost soil: Special soil made from weed-free fine compost and selected peat qualities. It supplies your plants with all the important nutrients over a long period of time and the high humus content makes light and heavy soils fertile.

In order for the pH value to be correctly determined, a pH test is required, which is available from various providers. If the measured pH value is too high, it can be reduced with rhododendron soil, lime-free peat or Epsom salt. It is best to plant hydrangeas in pots in pure rhododendron soil, then you don't have to worry about chlorosis.

Successfully combating chlorosis in hydrangeas

In very rare cases, there is also a real iron deficiency. However, this is more likely to happen with tub culture and not with bedding plants. If the pH value is okay and the hydrangea still has yellow leaves, then you have to fertilize. This can be done once through the leaf or quite normally through the earth. Pay attention to the correct concentration of nutrients when fertilizing the leaves, because if there are too many nutrients, the fertilized leaves can burn quickly. A commercially available fertilizer that is absorbed through the roots is also suitable. Our Plantura organic hydrangea fertilizer contains a small amount of iron, for example, in order to rule out an absolute iron deficiency from the outset. In addition, it is based on animal-free raw materials from the food, luxury and feed industries as well as mineral components that are also used in organic farming. So is ours Plantura organic hydrangea fertilizer truly "organic" and ideally suited for sustainable gardening.

More information on the topic Fertilize hydrangeas can be found in the corresponding special article.