Nitrogen deficiency
If there is a lack of nitrogen, the entire leaf usually turns yellow. At first only the older leaves are in the lower area of the hydrangea affected, only later does the leaves that have been driven back change color. As a result, the flowers can also wither.
also read
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remedy
Fertilize The hydrangea with a nitrogen fertilizer from the gardening trade. Please note the dosage indicated on the package and do not over-fertilize the hydrangea. Too much nitrogen can also damage plants.
Chlorosis
Iron deficiency is usually associated with those preferred by the Hydrangea acidic soils on. The younger to middle-aged leaves are affected first. They show a yellow-green to lemon-yellow discoloration. The leaf veins are sharply demarcated and dark green.
If the iron deficiency persists, the following damage occurs:
- All of the foliage turns yellow.
- Brown necroses develop from the leaf margin.
- The stems become thinner.
- The roots shorten and show an unhealthy brown color.
remedy
Fertilize Always use a special iron-containing fertilizer for the hydrangea. If an iron deficiency does show up, you can use a pure iron fertilizer.
Attention
Iron fertilizer is poisonous, which is why you should definitely wear protective clothing when spreading it.
Soil pH
In order to red hydrangeas keep their bright flower color, the soil must have a relatively high pH value. This can mean that the plant can no longer absorb sufficient amounts of iron. If yellow leaves appear on a red hydrangea, you should therefore correct the pH value. Organic fertilizers such as compost are well suited.
Tips & Tricks
Foliage that turns yellow in autumn is normal due to the natural vegetation cycle. The hydrangea is one of the foliage-shedding plants in which the leaves initially turn yellow in autumn and then fall off on their own.