Originating from the Mediterranean, oleanders belong to a genus of evergreen shrubs, cultivated above all for flowering and foliage.
Denomination: Nerium Oleander, oleander
It is a woody plant with a bushy habit that can range from 2 to 6 meters in height. The stem is erect and branched from the base.
The leaves in ideal climatic conditions are persistent: simple, leathery and lanceolate. The upper page is glossy, the lower one is gray and opaque.
The funnel-shaped flowers form corymbs and generally have 5 petals (in the simple form) but there is also a double shape. Colors range from white to carmine through pink, salmon and yellow.
It produces from mid-summer brown follicles, similar to pods, of about 10-15 cm that contain (when ripe) the feathery seeds.
The plant in short
|Origin||Middle East, Mediterranean|
|Type of plant||Evergreen shrub|
|Resistance to cold||Limited|
|Multiplication||Cutting in summer|
Repair from frost
|February||Repair from frost|
|July||Flowering, fertilization, cuttings|
|November||Repair from frost|
|December||Repair from frost|
Oleander cultivation does not present great difficulties as it is a very resistant species.
It can be planted both in the ground and in pots.
If it is young, it is convenient, during the summer, to top it often to obtain a dense bush and repot it at least every year. If it is old it is better to thin it from time to time and prune it at the base, in autumn or at the end of winter, to allow for new shoots in the spring.
Oleanders are sensitive to cold, prefer mild climates, requiring a minimum temperature of 5 degrees. In temperate climate zones it can therefore be grown outdoors, without requiring any protection. Vice versa in the northern regions it is good to repair it during the winter.
Flowers and fruits
The oleander flowers, which vary from pink to white, from red to yellow, bloom practically from the beginning of spring until late autumn. Several double-flowered cultivars have been selected.
The oleander produces showy fruits, of reddish-brown color, erect pods, 10 to 15 centimeters long.
Exposure, soil and fertilization
The oleander plant adapts well to any type of soil. To obtain abundant flowering it is important to provide abundant irrigation during the summer period. During the winter period the watering should instead be very reduced, especially in the northern regions. An exposition in full sun, bright and warm is recommended. This will guarantee excellent growth and flowering.
It is not very demanding regarding the terrain. It is better, if possible, to place it in soils rich in organic substance, but it does not disdain the poor ones. It is also important to avoid water stagnation.
The fertilizations must be regular to sustain the intense flowering. It is advisable to use granular fertilizers with long release or liquid fertilizers with a high potassium content every ten days.
Even better if we can dilute the liquid fertilizer and give it regularly with watering. The plant will particularly benefit from the constancy in nutrient administration.
Repotting and pruning
If the plant is cultivated in pot it is good practice to repot it every two years, fertilizing it with granular fertilizer and adding ox blood occasionally.
It is also advisable to prune young plants to obtain thicker hair.
They multiply by seed or by such during the summer period.
Attention: it is a very poisonous plant, in all its parts, containing glycosides active on the heart, which, for this reason, are used in medicine. It is therefore always advisable to wash your hands after touching it.
Pests and diseases
The most frequent parasite is the aspidote of ivy (Aspidiotus hederae), a parasite very common in Mediterranean countries. It is a particular type of cochineal, which mainly attacks the underside of the leaf. Another very common parasite is the fluffy cochineal (Chloropulvinaria floccifera) which succeeds in invading the plant reproducing itself practically throughout the year. The countermeasures must therefore be timely, since the parasite can lead to a serious deterioration and even to the death of the plant.
The honeydew produced ends up smearing the plant, often creating smokings.
The oleander is resistant, however it can happen that it suffers attacks from some parasites.
Among the most frequent we remember:
- The cottony cochineal: it can be observed on the underside of the leaves. It occurs with brown or white (similar to cotton) growths. Action must be taken by eliminating them with alcohol-soaked fabric (if the problem is not very extensive) or with specific products such as mineral oils and insecticides (possibly systemic).
- Fumaggine: it can be caused by aphids (but also by cochineal, metcalfa puinosa, whitefly). If their presence is massive, a black-brown layer (consisting of a fungus) will be produced on the leaves, which will bring the leaves to decay. In this case it is necessary to intervene eliminating the parasites with specific insecticides and then proceed with the washing of the leaves and with a curative anticryptogamic treatment.
- Red spider mite: it is a mite and can be seen on the underside of the leaves (tiny red or brown spots). The leaves turn yellow and look dehydrated. Its presence is felt especially when the temperatures are very high. It is capable of debilitating a beautiful plant in no time. To remedy the problem, the environmental humidity must be increased by vaporizing the leaves with water, not keeping the plants on very reflective floors and which may overheat (balconies, terraces) and intervene with specific products (acaricides).
- Other drawbacks are leaf spot and anthracnose. They can be prevented with copper-based anticryptogamics or, if necessary, treated with specific products.
In Italy the greatest difficulties can be given by the cold since the plant is not particularly rustic. The most serious damage is suffered by specimens grown in small pots as the earth could freeze completely. The advice is therefore to put them in large, especially deep pots, to withdraw them in a cold greenhouse (or to place them against a wall) and to protect them by covering them with special sheets.
If they are grown in the ground we will certainly have fewer problems, but, if in winter we reach really cold temperatures (-10 / -15 °), it is better to put them in sheltered areas, where at least they are not swept by the icy wind. Currently, particularly cold cultivars are available. If you live in a particularly rigid area it might be a good idea to consider orienting yourself precisely on these varieties.
Oleander is a plant that resists drought very well (and for this reason it is widely cultivated in low maintenance gardens or along roads).
In fact some modifications of the leaf stomata allow it to limit the loss of hydration.
This does not mean that the plant does not need to be watered regularly.
Already its name Nerium (from the Greek "neros" that is "water") tells us that to have a plant at its peak the irrigations must not be missing. In fact, in nature we find it right near water courses.
Obviously potted plants suffer more. In winter they can be kept fairly dry, but from spring to autumn they need a lot of humidity.
If you want to get the best from them it is even advisable, in the most torrid months, to fill the saucer with water daily.
These attentions are less important if the plant is grown in the ground. Having very deep roots (sometimes almost as long as the aerial part) it does not need frequent irrigation. This does not prevent us, especially if we live in particularly dry areas, from intervening a little more during the summer.
Propagation can be carried out using cuttings, layering, offshoots, seed or grafting.
Seeding is feasible, but given the long time required to obtain a good sized plant, it is used only if new varieties are to be obtained. The most used method, because it is simple and fast, is the cutting, to be carried out in late spring.
It can be done by inserting a semi-woody branch in the sand. In a few weeks we will see the roots grow. An alternative, even this rapid one, consists in putting a branch in a bottle of water and exposing it to the sun. When we see well-developed roots it will be time to transfer the new seedling into the pot.
The oleander is a very widespread and loved plant. For this you can find many different cultivars and over the years new colors and flower shapes have been introduced.
For example, today it is easy to find specimens from the double flower or bright yellow or salmon in nurseries.
However, many continue to prefer simple flowers. This is because the full-flowered varieties have the disadvantage of not being self-cleaning. This means that the flower most often dries or rots on the branch, forcing the gardener to intervene periodically. The plants with simple flowers instead let the petals fall and therefore the specimens always look clean.
Breeders have not only focused on aesthetic qualities. Varieties that are more resistant to cold and some of a particularly small size have been created.
Some particularly cold-resistant cultivars are: Blanc, Provence, Villa Romaine, Italy, Pink beauty, Luteum plenum, Madame de Billy, Margaritha, Osiris, grandiflorum, cheyenne, navajo. Dr. Attilio Ragioneri.
And here are some dwarf varieties, more suitable for growing in pots. The maximum height they reach is 1.50 m:
Petite Salmon, Moshav, Hardy Red, Oasis, Red Beauty, Angiolo Pucci, Caro, Fiesta Pienk, Fiesta Rodi.
Some particularly fragrant varieties have also been selected, especially during the hottest hours of the day
Agnes Campbell, plenum album, Eugenia Fowler, grandiflorum, Luteum plenum, Madame Allen, Magnolia Willis Sealy, Navajo, Mont Blanc, Mrs Burton.
Oleander - Nerium oleander: Medicinal properties
The oleander is a completely poisonous plant. The poison is found in all its parts, but especially in the leaves and in the bark. Poisoning causes gastroenteritis, vomiting, fever, diarrhea, irregular heartbeat and death.
Care must therefore be taken when touching the leaves, cutting branches or repotting. Be careful even when children or animals are present.
There are many legends that speak of the poisonous nature of the oleander.
It is already present in the Metamorphoses of Apuleius. The protagonist, turned into an ass, takes him for a rose and is about to eat them, but, fortunately, at the last minute he notices the difference and desists from his intent.
It is also said that having slept on a bed of oleander leaves was the cause of death or serious poisoning for an entire brigade of French soldiers during the war in Algeria.
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The oleander is a shrub typical of the Mediterranean vegetation, it is widespread throughout Italy in cultivation, in the areas mer
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