Basically, yellow leaves on oleanders are a completely normal phenomenon and nothing to worry about. Although this plant is an evergreen species, the foliage is subject to aging and is shed after two to three years and replaced by fresh leafy green. However, reasons other than the cause listed here can also lead to yellowing of the leaves.
Yellow leaves can be a sign of nutrient deficiencies
Unsuitable location
Oleander loves a warm place in the sun, but it should also be sheltered from the wind. The Mediterranean plant does not tolerate wind, it turns yellow. A change of location is also problematic, for example when moving from winter to summer quarters. This should always be done carefully and in stages so that the plant can get used to it.
nutrient deficiency
If a lot of leaves turn yellow in a short time, this can indicate a nutrient deficiency. The oleander is one of the heavy feeders and must therefore be fertilized regularly - especially if it is cultivated in a bucket. With insufficient fertilization, the yellow leaves are an indication of a deficiency, often of nitrogen and/or potassium. Fertilize oleanders at least once or even twice a week during the growing season with a good flowering plant fertilizer.
lack of water
In its natural habitat, the oleander likes to grow on river banks that are flooded from time to time. So the plant is used to having wet feet frequently. Oleander needs a lot of water and is one of the few species that tolerates waterlogging. If there is a lack of water, the leaves can turn yellow and eventually be dropped.
Warm wintering
Another common cause of the yellow leaves of the oleander can be too warm a hibernation, for example if you put the plant in the warm living room during the cold months. In winter, the evergreen oleander needs a break, so you should put it in a cool, but frost-free and bright place. The lack of winter light can also cause yellow leaves.
tips
If other causes are out of the question, check the size of the bucket. Choose the largest possible pot size, as the roots of the oleander need space. In addition, the plant should be repotted once a year.