The oleander is an evergreen plant, and these evergreen plants do not keep their leaves all their life, but occasionally shed leaves that are replaced by new leaves. Each plant has a slightly different rhythm in which it gets rid of the oldest leaves, they then turn yellow and the oleander then throws them off after a while.
Table of Contents
So if you haven’t had your oleander long, you should just watch the yellow leaves for a while, maybe nature is just taking its course here …
The only way to stop this natural yellowing is through constant tapering cuts, see below, and that is not complete either, at some point the leaves are just too old.
Wrong location or change of location
You have certainly given your oleander a nice, warm and sunny place in the summer, but what is occasionally forgotten is that the oleander does not like wind either. If it is not well protected from the wind, it could cause yellow leaves that will only grow again in a more comfortable location.
In addition, an oleander often reacts with yellow leaves when it has been relocated. Even the change of location from winter quarters to summer quarters can be enough if it happens too abruptly. If it has happened there is not much left to do, the next time you should prepare your oleander in stages for the summer season.
Of course, it depends on how many leaves turn yellow in what time – if a lot of leaves turn yellow in a very short time, it is certainly no longer natural aging. If the yellow leaves appear evenly distributed, the oleander usually suffers from a lack of nutrients.
That goes very quickly, because oleander plants are among the heavy eaters. In their natural locations on river banks, they are often flooded once, in this water there are many nutrients and a lot of lime every time. Oleander should therefore actually be planted in soil with a slightly alkaline or at least neutral pH value (between 6 and 8.3), and some nutrient-rich compost should also be mixed in, with a little bit of clay if desired.
If this is neglected, the oleander must be fertilized even more, during the growing season at least once or even twice a week with normal fertilizer or with slow release fertilizer at the beginning of the season. The fertilizer should contain a lot of nitrogen and a lot of potassium, an NPK mixture 15/8/12 (15% nitrogen, 8% phosphate, 12% potassium) could give the oleander z. B. liked, in the bucket best with trace elements and magnesium.
If there are omissions here, if an oleander quickly develops yellow leaves, then you should touch it up and will have to wait a while for the deficiency symptoms to develop.
Yellow leaves due to lack of water in the oleander
And it depends on where the leaves turn yellow – discoloration and leaf loss can also be caused by a lack of water in the oleander, an indication of this is when the discoloration starts inside the oleander. The generic name of the oleander gives the first appropriate hint: Oleander belongs to the genus Nerium, and that comes from the Latin nerium = wet. In nature, oleanders prefer to grow in valleys through which flowing waters lead, they are one of the few plants that have nothing against waterlogging, they are constantly inundated on the riverbank and the roots usually grow into the groundwater area anyway.
An oleander also needs plenty of water from above, in warm weather it is better to have too much than too little; this is where it differs from most other houseplants or potted plants. If the soil in the pot dries out properly, this later leads to supply problems and often to yellow leaves.
They’ll disappear again at some point if the oleander gets enough water from now on. You can prevent this by holding the oleander under the pot with a saucer, which is always filled with a few centimeters of water.
You could also have meant it too well in another direction, namely if you live in an area with very hard, chalky water and if possible avoid watering the plants with this tap water. This is correct for most plants, they prefer lime-free rainwater, but not for oleanders, which usually like lime-containing water very much. But be careful, only try it if there are indications, there are now cultivated forms that love the soft rainwater.
Yellow leaves as a result of incorrect wintering of the oleander
An oleander wants to be kept cool in winter, with less water and without fertilizer, between 5 and 10 degrees, if it had to survive overwintering in a heated living room, this can also lead to yellow leaves. If you have to overwinter your oleander in the living room or maybe even in a dark and warm place because you don’t have a cool, light room, you should move it out of the summer as late as possible and take it out again as early as possible, otherwise the lack of light will keep coming back cause yellow leaves.
That was true for the oleander in the bucket, if you live in a mild region and have planted one of the hardy oleander varieties in your garden, it could simply be that the “mild region” turned out to be not mild enough last winter or that the winter protection was insufficient. Oleander in the garden is always critical in Germany, we can only provide USDA hardiness zone, which is the absolute lowest limit for an oleander that is used to winter hardiness zone 10, and these winter hardiness zones only give average values. Then it could be that your oleander not only develops yellow leaves, but largely dies above the ground, then you can only wait to see whether it sprouts again in spring and give it better winter protection in the next year.
Wrong keeping of the oleander in a bucket
If your oleander “lives” in a tub, it needs the right soil. It is best to use garden soil, possibly increased the pH value with lime, mixed in with compost and some clay for the nutrient supply.
He also needs space in the bucket, enough space to develop his roots. Young plants usually need a larger bucket every year, older plants always when the soil in the bucket consists almost entirely of roots, if you were too slow here, your oleander could acknowledge this with yellow leaves.
Then repot and wait, when your oleander is already in the largest possible bucket, as much soil as possible is removed and filled with fresh soil, you should also prune roots and shoots at the same time.
Trimmed incorrectly or not enough?
Perhaps your problem child is an oleander that has received too little attention for a long time. Then there was usually no regular pruning, which the oleander urgently needs.
This omitted pruning then indirectly ensures that the oleander gets yellow leaves: Oleander is a woody plant, if it is allowed to grow in front of itself without pruning, the branches in the inside wood first, while the outside area, which is directly exposed to light, becomes woody of the oleander form new shoots with young leaves. Where the shoots become lignified, leaves of considerable age are quickly on the shoot, and they then die off at some point. Only if you regularly remove the oldest shoots from the oleander by pruning, can it develop new young shoots all around, which then also have new young leaves that do not turn yellow.
If your keeper is already quite bald, only a radical cure will help. You cut the entire shrub back to the roots, except for a few strong young shoots that are about 20 cm long. From these the oleander will now develop anew, with fresh green leaves.
This should really only happen to you if you are dealing with a red or pink-blooming oleander, white and yellow-blooming varieties should always form new shoots from the base and thus hardly lose their baldness.
Yellow leaves from pests or diseases
Oleander can be attacked by scale insects, thrips or spider mites, especially during winter, which can also cause yellow leaves and must be controlled.
The treatment of the yellow leaves on the oleander
Depending on how many yellow leaves you have to eliminate, you can simply cut away the yellow leaves as part of the normal spring pruning or use the malformation as an opportunity to give your oleander the radical rejuvenation pruning, which may have been due for some time to undergo.