Herbs

Oleanders: Detect and treat care errors

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The oleander originally comes from the Mediterranean and is very robust in its home. Maintenance errors, on the other hand, can quickly make trouble for us.

© Shchipkova Elena - Fotolia.com

The oleander (Nerium oleander) is a plant from the Mediterranean, which also blooms in our latitudes and is mostly kept in tubs. In its home country, the oleander is a robust plant that hardly needs any maintenance. The container plants in the garden and on the terrace are however less resistant. Maintenance errors harm the plant and are noticeable through different symptoms. Recognized in good time, they can be treated well.

content

  • 1 The right location - Oleander is a sun child
  • Avoid casting mistakes - oleanders are thirsty
  • 3 Be careful when cutting back - less is more
  • 4 Missing flowers - why is it?
  • 5 falling leaves - causes and tips
  • 6 problems in the winter quarters
  • 7 Detect and fight pests on the oleander
    • 7.1 Home remedies for pest infestation
  • 8 The best recipe for healthy oleander plants

The right location - Oleander is a sun child

A sunny location is particularly important for the Mediterranean plant. The plant loves direct sunlight and therefore a south-facing garden or balcony. If the leaves wilt or the flowers fail to appear, it may be in the wrong location. It should be noted that the plant should be protected from wind and rain. If the oleander loses its flowers, it was probably exposed to the weather and should move to a protected location as soon as possible. A roof or a location directly on a house wall is an option.

Avoid casting mistakes - oleanders are thirsty

Not least due to the sunny position, the plant needs sufficient water. Container plants in particular must not dry out. Bedding plants are a little more robust, but will also wither quickly and show themselves as rotten if not enough water is given at least twice a day. On particularly hot days, you should water three times a day. With potted plants, the water requirement can be better controlled if you place the plant pot in a saucer. Otherwise, a simple trick helps: just stick your finger in the ground. If this remains dry, the plant urgently needs water.

Many plants love watering with rainwater. The oleander is an exception here. If the oleander is kept as a container plant, permanent additions of rainwater can disturb the balance of the soil and make the soil acidic. If the plant does not want to grow and shows pale leaves, this indicates a lack of nutrients. This occurs when the acidic soil prevents nutrient absorption. This deficiency can be compensated for by pouring with tempered, calcareous well water instead. Tempered water also ensures a abundance of flowers. If you still use rainwater, you should regularly limescale the floor to avoid this maintenance error.

Be careful when cutting back - less is more

Many types of plants tolerate radical pruning. The oleander is not one of them. If a vigorous pruning is carried out in autumn, the flowers will probably not appear in the coming summer, because the plant only flowers on two-year branches. However, the oleander has no objection to an occasional topiary, on the contrary, it becomes more robust and resistant. However, if you miss the pruning completely, older plants will become bald and unsightly. Leaves only form on the tips of the shoots. In this case it is advisable to cut all shoots down to approximately finger strength. You need a little patience, but fresh shoots will appear soon.

A maintenance mistake is also to cut off old inflorescences. This also removes the base for the new flower. The plant rejects old inflorescences independently.

Missing flowers - why is it?

Oleander is valued for its abundant flowering that occurs between June and September. If, on the other hand, you wait in vain for the flowers to bloom, there can be a whole range of maintenance errors. Action is required if the plant does not grow and produces few to no flowers. There are several possible causes:

  • The plant is too cool.
  • The plant is too dark.
  • The plant gets too little water.
  • The plant does not get enough nutrients.
  • The plant is infested with pests.

First of all, the location must be checked. The plant needs a lot of sun and has to be protected at the same time. Warmth and sun are the main indicators of abundant flowering. Oleander must also always be watered sufficiently. The best way to check this is to place the tub plants in a mat filled with water. A lack of nutrients can be related to a lack of fertilization and an unfavorable soil condition. Pests that can affect the oleander can be identified with the naked eye. We will go into this further below.

Falling leaves - causes and tips

If the oleander loses its leaves, there is not always a maintenance error. Especially if the plant suddenly gets yellow leaves, it is important to keep calm. An oleander leaf can live for a maximum of two years. Before decrepit leaves are shed, they turn yellow. At the same time, the new leaf growth begins. So it is usually a regular process and not incorrect maintenance. Yellow leaves can also be the result of a too dry stand. In the case of falling leaves, first check whether the plant is adequately supplied with water.

If the leaf margins turn brown and then fall off, the sun child Oleander may have gotten a sunburn. This happens when the plant is moved too quickly out of the cool winter quarters in spring and is exposed to the blazing sun. Sun protection is an advantage in the first few days at the new location. No further intervention is necessary. The leaves will usually grow back fresh and healthy quickly.

Problems in the winter quarters

Oleander cancer:

If you really want to hibernate your oleander, you should check it frequently in your winter quarters. If there are dark spots on the stems and shoots, the plant could be infected with oleander cancer. The following signs can occur:

  • Inflorescences are not fully developed.
  • Cripple flowers and seed pods.
  • Shoots burst open.
  • There are growths reminiscent of cauliflower.
  • Leaves turn brown.
  • Brown spots on the leaves burst open.

The signs are often misinterpreted and attributed to too dark standing or too little water. Oleander cancer is caused by a bacterium that is believed to contain all plants found in Europe. Whether the disease finally breaks out depends on the external conditions and the general resistance of the plant. The disease usually breaks out in winter quarters. Oleander cancer cannot be treated biologically or chemically. Affected shoots must be cut back as soon as possible, since the growths spread quite quickly. Then you should leave the plant in the winter quarters. Make sure there is enough light and ventilate regularly!

Blight:

Dry rot is a fungal disease that also often affects the winter location. Since the fungal spores spread through water, plants that are not protected on rainy summers are often affected. The inflorescences and all above-ground soft parts of the plant are particularly at risk. The dry rot can be seen in brown spots on the shoot. The shoot overlying the affected areas can no longer be saved and dies. Because the fungus spreads quickly through moisture, quick action is required. It is not uncommon for the infected plants to die completely.

Plants infected with dry rot must be cut back radically. The cut shoots do not belong on the compost. Dispose of them in the household waste or burn the infected plant parts. The pruning must be carried out into the healthy wood. The resulting wounds should be sealed with tree wax. This is particularly important if the cut has been made before moving to the winter quarters.

Detect and fight pests on the oleander

The plant is susceptible to a number of pests. These include scale insects, aphids, spider mites and mealybugs. If the plants are too warm in winter, they are particularly susceptible to pests.

Scale and aphids:

The plant is particularly susceptible to scale insects. It is therefore advisable to check the undersides of the leaves regularly. If there are sticky spots there, the closer armor of the scale insects can be seen on closer inspection. The pests adapt to the leaf color and can only be identified if a careful leaf control is carried out. The same applies to aphids. However, aphids are less common in oleanders.

Spider mites:

The spider mite poses a real danger to the plant. Spider mites are easily overlooked by the naked eye. Plants that actually have an ideal location, namely protected on house walls, are increasingly attacked by spider mites, as these are carried by the wind. If the plant is free and drafty, spider mite infestation is less of a problem.

The first sign of spider mites is a lightly spotted central panicle of the leaves. The spider mites are increasingly sitting on the underside of the leaves. A fluff reminiscent of cobwebs is visible there. In the advanced stage, the entire leaves turn silvery and fall off. The trade offers effective preparations against spider mites, including harmless agents based on rapeseed oil. The entire plant should always be treated. If the plant is severely infected, it is advisable to repeat the treatment after about two weeks.

Home remedies for pest infestation

  • You can get rid of scale insects with an old toothbrush.
  • A hard water jet helps against mealybugs and spider mites.
  • Pests can be removed with a lye from soft or curd soap.
  • Set up the insect hotel and attract predators (build insect hotel instructions).
  • Treat the plant with stinging nettle (recipe for stinging nettle).

Important: All parts of the oleander plant are poisonous! Wear gloves when working so that the plant sap does not come into contact with the skin.

The best recipe for healthy oleander plants

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