Yellow leaves on geraniums: recognizing and treating chlorosis

Yellow leaves can indicate a nutrient deficiency in geraniums. We explain how to correctly identify and combat chlorosis in geraniums.

Many adorn your windowsills and gardens with geraniums, which also pelargonium (pelargonium) to be named. They bloom in a wide variety of colors - from white to pink to various shades of red. Here you can find out what you can do to prevent unsightly yellow discolouration on geranium leaves.

There are many different causes of chlorosis in geraniums - from a lack of nutrients to temperature fluctuations.

Recognizing chlorosis in geraniums

Different types of chlorosis can appear on geraniums. For example, chlorotic yellow spots form all over the leaves, or chlorosis begins at the edge of the leaf or at another part of the leaf. What all chlorosis have in common is the yellowing of the green leaves, which can lead to the death of the leaf tissue, a so-called necrosis.

Reasons for chlorosis on geraniums

One of the most common causes of geranium chlorosis is a nutrient deficiency. Depending on the type of deficiency, the chlorosis occurs in different places. Therefore, observe the geranium leaves closely to determine which nutrient deficiency it could be:

• Boron deficiency: Necrotic and chlorostic spots form at the base of the leaves on middle-aged leaves and spread along the veins
• Iron deficiency: yellowing of the young leaves between the leaf veins
• Copper Deficiency: Yellowing starts at the base of the leaf and spreads to the edges of the leaf
• Magnesium deficiency: yellowing of the older leaves between the leaf veins
• Phosphorus Deficiency: Chlorotic patches on lower, older leaves that expand and turn reddish-purple

However, there are also abiotic causes that can affect geraniums and trigger chlorosis. These include the following causes:

• Sunburn: Indoor geraniums are often burned through the glass by the sun and then show yellow-brown spots; sunburn also causes necrosis (dead brown leaf zones)
• Heat damage: At temperatures above 28 °C, chlorosis and later necrosis can occur on the tips of the shoots
• Cold damage: At temperatures below 8 °C, chlorosis forms on the tips of the shoots
• Temperature fluctuations: Cold nights combined with warm daytime temperatures can cause yellowing of older leaves; red leaf edges can also appear

The growth conditions are also decisive for the occurrence of chlorosis on geraniums. pests like that white bow tie (Trialeurodes vaporariorum), spider mites (Tetranychidae) or mealybugs (pseudococcidae) can also cause yellow discolouration, but this is only a matter of sucking damage by the insects.

Prevent chlorosis in geraniums

As mentioned above, chlorosis can have many different causes, so there are many methods of preventing chlorosis.

First and foremost, this includes an optimal supply of nutrients. With appropriate fertilization, chlorosis can be prevented from the outset. Also, make sure that your geraniums don't thrive in a pot that's too tight, as that won't just cause them to a lack of nutrients, but also to depletion of the soil and limitation of the absorption capacity of the roots come. Provide the geraniums with plenty of nutrients right from the start by mixing a fertilizer with the substrate when planting. Special flower fertilizers, such as the Plantura, are suitable for this Organic flower fertilizer, which contains 4% nitrogen, 2% phosphorus and 7% potassium, guaranteeing your geraniums a good supply of nutrients. Here you can find out more about the ingredients and the application of the Plantura organic flower fertilizer. information about Care of geraniums can be found in our special article.

Since chlorosis can also be caused by external factors such as temperature, you should avoid exposing your geraniums to temperatures below 8°C or above 28°C. Indoor geraniums often suffer from sun damage - especially the leaves that are attached to the window panes. Such locations should therefore be avoided.

with yellow boards you can monitor whether the discolouration is caused by pests such as whitefly or has another reason. You can simply put them in the flower boxes and check regularly whether animals are sticking to the layer of glue. You can find out more about yellow boards and which pests they can be used against here.

Eliminate chlorosis in geraniums

If your geraniums suffer from chlorosis caused by a lack of nutrients, you can easily remedy this by fertilizing. You can use special geranium fertilizers that not only contain nitrogen, phosphorus and potassium, but usually also have an extra shot of trace nutrients. These fertilizers often come in liquid form, so you can simply mix them with the irrigation water and fertilize the geraniums with it.

If your geraniums are planted in a pot that is too narrow, there is no avoiding repotting. The additional space and the fresh and nutrient-rich substrate will help the geranium get going again. You can also mix fertilizer with the plant substrate when repotting to give your geraniums the best possible care. Here you will find everything you need for that plants of geraniums should know.

Summary Preventing Geranium Chlorosis:

• Balanced nutrient supply
• Use flower or geranium fertilizer
• Do not plant in pots or flower boxes that are too narrow
• Avoid temperatures below 8 °C and above 28 °C

More information about Care of geraniums can be found here in our special article.