The cherry laurel is undoubtedly one of the more robust plants in the garden – but it can also weaken. A common symptom is yellow or brown leaves. We explain what’s behind it and what you can do about it.
Cherry laurel (Prunus laurocerasus) is an extremely popular hedge plant. Many gardeners are already calling them – not without a wink – the thuja of the 21st century. Regardless of taste: Anyone who owns a cherry laurel hedge naturally wants it to look good and not have yellow leaves. In the following sections, we’ll explain the five most common causes of yellow or brown leaves and tell you what to do about them.
Soil compaction and waterlogging
Basically, the cherry laurel does not have high soil requirements. It grows on almost any surface in the sun and shade and also knows how to assert itself in the dense root system of dominant tree species such as birch and norway maple. However, the evergreen jack of all trades does not feel particularly comfortable on damp, poorly ventilated soil. It is naturally deep-rooted and therefore appreciates soils that are well ventilated and loose into the subsoil. Compacted layers, over which the rainwater accumulates, cause the plants to take care of and shed their leaves over time.
If waterlogging and soil compaction are the causes of yellow leaves, these usually appear in the first few years after planting – so it is not too late to dig up the plants again, loosen the subsoil and then re-plant the trees to use. If possible, work in as much coarse construction sand as possible so that the soil remains permanently loose and the water also drains off well in the future. Admittedly, this is a very high effort, but unfortunately it is the only way to eliminate this cause.
Sunburn or frostbite
The cherry laurel grows easily in full sun with a good water supply. On drier soils, however, it should get a more shady location, otherwise there is a risk of leaf burns in high solar radiation. The same thing can happen in winter when the ground is frozen – in this case one speaks of the so-called frost drought. Leaf burns in summer can usually be recognized by the fact that the leaf is not uniformly yellow everywhere. It usually only affects those areas that are particularly exposed to sunlight. When it is frost-dried, however, whole branches are often yellow and dried out. The large-leaved ‘Rotundifolia’ variety is particularly susceptible to frost damage, while ‘Caucasica’ and ‘Etna’, for example, are considered robust.
Large-leaved varieties are usually a little more prone to sunburn than small-leaved ones. Like conventional drought damage, sunburn can best be avoided by watering the plants in good time. Irrigation also helps against frost drought, provided the ground is not frozen. A fleece cover offers additional protection against the drying winter sun. However, it is only practicable for individual plants. Autumn fertilization with Patentkali at the end of August increases the resistance of the leaves to frost damage.
Bad water supply
The cherry laurel is actually quite drought tolerant and lasts a surprisingly long time even on drier sandy soils until the first symptoms of drought stress appear in the form of yellow leaves. This advantage is also a disadvantage that almost all evergreen trees have. The coarse leaves react much more slowly to drought than the light, thin leaves of deciduous woody plants. Drought stress often only becomes visible when the water supply has long since returned to normal – and drought has been ruled out as a cause. Nevertheless, a lack of water is a very obvious cause of yellow leaves, especially after dry summers, which can also be removed quite easily. In order to improve the water storage capacity of sandy soils in the long term, the plants should be mulched regularly with leaves or other organic materials. They are broken down into humus by earthworms and other microorganisms and incorporated into the soil.
Cherry laurel with shotgun disease
If the leaves are partly unevenly marbled yellow and show round holes in some places that look like they have been punched out, an infection with the shotgun disease is likely. It is not life-threatening for well-ingrown shrubs, but of course it still tarnishes the appearance of the plants. In the case of acute infestation, you should remove the infected leaves and shoots with secateurs and then treat the plant with a fungicide if it is still young and not very resistant. If older plants are infected, spraying with environmentally friendly sulfur preparations is usually sufficient to prevent the infection from progressing any further.
Yellow leaves due to a lack of nitrogen
Yellow colored leaves can be an indication of nutrient deficiency. If the leaf veins are also yellow, this is mostly due to an insufficient supply of nitrogen. If they are still green and sharply demarcated, iron is usually missing. Both can easily be remedied with appropriate, fast-acting mineral fertilizers, whereby iron deficiency can also be a reason for a very high pH value in the soil. In this case, measure again to be on the safe side with a test set from a garden specialist. If you provide your cherry laurel with around two to three liters of compost per square meter every spring, it is well supplied with all the important nutrients.
No matter what the cause: a damaged cherry laurel can usually be brought back into shape within one season by pruning it. The woody plants are extremely regenerative and can easily sprout again even from several year old unleaved branches.