If brown spots appear on the leaves of the hydrangea, there are three possible causes. In addition to pests and fungal infestation, care errors can also be the cause.
What causes hydrangeas to have brown leaves?
Brown leaves on hydrangeas can be caused by sucking pests such as spider mites, fungal infestation, lack of water or over-fertilization. Treatment can include insecticides containing rapeseed oil, appropriate fungicides, or adjusted irrigation and fertilization practices.
Sucking Plant Pests
If your hydrangea initially has yellowish leaves and then brown leaves, the plant is often infested with spider mites. The tiny insect pests are only about half a millimeter in size and are therefore barely visible to the naked eye. As a result, the infestation is usually only discovered when the extremely fine webs become visible.
Remedy
Spray the plant with insecticides containing rapeseed oil and make sure that the undersides of the leaves are also thoroughly wetted.
Brown leaves due to fungal attack
You can recognize leaf spot fungi by the brown spots on the center of the leaf. The leaf tissue initially becomes thin and eventually tears in the affected areas.
Remedy
Remove all diseased plant parts and dispose of them in the household waste. Under no circumstances should the infected leaves be added to the compost as the fungi survive there. When spreading the valuable fertilizer, you would unintentionally spread the spores throughout the garden and promote new infection. If the infestation is severe, spray the hydrangea additionally with a suitable fungicide.
Care errors
The hydrangea is one of the very thirsty plants. It reacts very sensitively to a lack of water, which is noticeable in the early stages by drooping flowers and leaves. If the plant is not watered enough, the foliage dries up and turns brown.
Too much fertilizer can also lead to brownish leaf discoloration. The leaves of an over-fertilized hydrangea dry from the edge and are subsequently thrown off.
Tips & Tricks
Hydrangea pots offered in early spring are almost always grown in the greenhouse and brought to bloom prematurely. This makes the plants susceptible to change and often turns brown leaves as soon as they are moved outdoors. So slowly get these hydrangeas used to the change of location.
