Oleandro

Class

Dicotyledons

Division

Angiospermae

Family

Apocynaceae

Order

Gentianales

Genus

Nerium

Species

oleander

Description

Shrub or small evergreen tree with an upright habit and globular crown. Its landscaping and ornamental value, conferred by the luxuriant summer flowering with inflorescences of elegant and vibrant colours, make it suitable for cultivation both in the garden, as a single specimen, in homogeneous groups or in compositions with other flowering species, and for balconies and terraces in large pots and planters. Its use for creating plant barriers or in flower beds and roundabouts in urban areas is interesting. Rustic, prefers full sun exposure and regular watering.

Variety description

Shrubby plant that is also cultivated as a sapling with a central stem and open, rounded apical branching. Very hardy genus that withstands both low temperatures and summer heat. Evergreen, elongated leaves with persistent and recurrent flowering during the summer period. Species with many varieties with blooms in a wide range of colours. Suitable for many gardening uses, in pots in terraces, for urban greenery and the Mediterranean landscape. It has no particular diseases and is therefore of wide use. Requires little post-planting cultivation care.

Curiosities and special features

The generic term Nerium, attributed by Linnaeus in the 18th century, derives from the Greek word naros meaning moist or cool in relation to the plant's natural habitat as river and stream beds, while the specific epithet derives from the Latin olea meaning olive tree referring to the shape of the leaf blades similar to those of the olive tree.

Oleander is one of the plants that survived the atomic bombing of Japan and thus became the official flower of Hiroshima.

Origin and distribution

A species native to the Mediterranean and Myanmar; commercially present today, thanks to intensive genetic improvement work also carried out in Italy, with a wide assortment of varieties that differ in cold resistance and vigour as well as in flower type and petal colour shade.

Leaf

The leaves, leathery and with an obvious central rib, have an elongated lamina.

Flowering period

Flowering is lush and persistent, lasting from late spring to late summer for 30 to 60 days.

Inflorescence

It has elegant terminal corymbal inflorescences.

Leaf colour

The leaf blade is solid-coloured, enhancing the colour tones of the inflorescences.

Plant height

The height of the plant varies from 1 to 4 m, depending on cultivation conditions.

Lifespan

Shrub or small perennial evergreen tree.

Where to plant

Versatile in its use, it is suitable as a plant for flowerbeds, balconies, borders, planters, gardens and parks, large flowerbeds and roadside roundabouts, large pots, in flowerbeds or outdoor borders in temperate zones, open field, hedges, terraces

Stem

The plant has a semi-woody stem, branched from the base and with smooth grey-green bark.

Flower

It flowers from late spring to late summer, with a flowering period of between 30 and 60 days. It is not particularly attractive to pollinating insects.

Growth

It presents a globular growth, ideal for creating homogeneous groups.

Plant habit

The erect habitus is reinforced by straight, flexible branches bearing terminal inflorescences.

Branching

The abundant branching allows for a density of foliage and flowers with a highly ornamental result.

PH

It prefers a slightly acidic soil or substrate pH, with optimum values between 6.0 and 6.5.

Soil preparation

Before transplanting in late autumn, prepare the soil by removing any weeds and bulky pebbles, and also apply organic or slow-release chemical fertiliser for ornamental flowering plants.

Sun exposure

A heliophilous species, exposures in bright shade and full sun are necessary for compact growth and lush flowering.

Ideal climate and temperature

The ideal temperature is between 0.0 and 30 °C; it tolerates hot summer weather well. There are also varieties that show greater resistance to winter cold. In general, Oleander, due to its adaptability, is ideal for use as a garden plant in a wide range of climates, although a temperate Mediterranean climate is best. If grown in pots, protection with non-woven fabric or shelter in a light room is recommended in the presence of harsh winters.

Use

Oleander is widely appreciated by professionals and landscapers in:

Ornamental Outdoor ornamental Outdoor Landscape Design Landscaping Environmental consolidation plants

Hardiness

Oleander ishighly rustic, adapting to different soil and climate conditions and temporary drought.

Soil

For proper root development the soil must be light and well draining, fresh and moist in depth. In pots and planters, use a new, high-quality substrate of peat or perlite, alternatively peat mixed with clay granules, wood fibre and lapilli.

Difficulty

Following proper establishment in the new planting site, it requires little post-planting cultural care.

Growing tips

Here are some aspects and cultivation conditions for best results in vegetative vigour and flowering:

Can also be planted in flower beds in full sun. Requires little but regular fertilisation Exposure to direct light

Combinations with other plants

Oleander is suitable both as a single specimen, grown as a small tree, and in homogeneous groups to create, for example, hedges or plant barriers. When grown in the garden, it is also interesting to use in compositions with other ornamentals such as Lavender and Rosemary.

Planting

When transplanting, take care not to damage the roots and position the plant with the collar above the soil surface. Plant the young plants in loam or loose, light soil to promote root development; compact the soil well to avoid the formation of air pockets and water without producing waterlogging.

Pruning

To be pruned in late summer, at the end of flowering, according to the need to limit growth in both width and height. Although tolerant to drastic pruning, it is recommended to intervene with suitable cuts, respecting the natural habitus of the plant.

Propagation

Multiplication is by grafting, micropropagation or cuttings.

Repotting

If grown in pots or planters, the soil must be renewed every two years or at least supplemented with new soil and organic fertilisers.

Watering

Although it is a drought-resistant plant, constant and balanced watering is recommended, even several times a week if the season is very hot. Prevent both prolonged dry spells and water stagnation. Apply water directly to the soil or substrate, without watering the aerial part of the plant directly.

Fertilising

When preparing the soil for transplanting, carry out a background fertilisation. Subsequently, in spring and early summer, carry out periodic fertilisation, without overdoing the doses, by applying slow-release granular fertiliser specifically for ornamental flowering plants to the soil or substrate. A lack of nutrients can lead to yellowing and dropping of the basal leaves.

Pet safety

Toxic species.

Edibility for humans

Non-edible.

Toxicity for humans

All parts of the plant are toxic if ingested as they contain the cardiotoxic glycoside oleandrin, which causes poisoning. Burning the wood gives off a smoke that is also toxic. The sap also causes skin irritation, so wear gloves when handling.

Tip

Oleanders are plants that need constant but balanced watering; even several times a week if the season is very hot. They love direct sun and also tolerate limited periods of drought, but should be watered as soon as possible. They should be pruned as required to limit their growth in both width and height. They tolerate drastic pruning. They can also be grown and planted as trees, with a single central stem and round crown.