Nerium oleander Roseum Plenum

The Rose Bay 'Roseum Plenum', Nerium oleander in Latin, is undoubtedly one of the most beautiful citrus trees of summer. It produces a quantity of beautiful large double flowers, displaying a lovely deep pink and apricot colour, grouped in generous bouquets with exquisite fragrance. They bloom as long as summer lasts, as long as the soil does not dry out too much. It is in every way an excellent evergreen bush for mild climates, very floriferous, easy to cultivate, and resistant to sea spray and drought. Oleander is not demanding when it comes to soil type and has astonishing adaptability to the most difficult conditions; its only weakness is its rather mediocre hardiness, especially during its early years. It is best grown in the ground in regions that do not experience extremely cold winters. Planted in a large pot, it is the star plant of summer that can be displayed on the balcony, terrace, patio, and even in a small garden, near the house.

The numerous cultivars of Oleander available in the horticultural market are mostly hybrids between the Nerium oleander subsp. oleander, which grows spontaneously around the Mediterranean, and the highly fragrant Nerium oleander subsp. indicum, which grows spontaneously from Iran to China. They offer an almost infinite range of colours, from white to pink, yellow and salmon, red, and even mauve. Only the blue shade is absent.

Nerium oleander is an evergreen bush belonging to the citrus tree family, just like periwinkles or false jasmine (Trachelospermum jasminoides). The 'Roseum Plenum' cultivar is particularly floriferous. It naturally forms a bush with a dense and bushy habit, branching near the base, and with a generally rounded shape. It will reach an average height of 3m (9ft 10in) and a spread of 2.50m (8ft 2in) at maturity, with rapid growth. Its flexible branches, covered with grey bark, bear long evergreen leaves, thick and leathery, with a slightly ashy green colour and a lighter undersides. They measure 10 to 15cm (3.9 to 5.9in) in length and 3cm (1.2in) in width. In case of intense drought, Nerium sheds some of its leaves, particularly the oldest ones, located near the base of the stems. The flowering takes place in spring, then again from late summer to autumn or continuously from spring to autumn depending on the climate, lasting for 4 to 5 months in moist soil. The flowers are composed of a tube widening into numerous petals of a deep pink colour with an apricot throat. They are gathered in corymbs, mainly at the terminal part of 1 or 2-year-old branches. This nectar-rich and honey-producing flowering is followed by the formation of long reddish pods that burst open when ripe, releasing a multitude of small seeds with a bouquet of white bristles, dispersed by the wind. Be careful not to prune Oleander too severely: only the stems that have reached a certain length bear flowers!

A symbol of resistance and generosity, Nerium oleander is an excellent coastal hedge plant and also a magnificent specimen to plant in isolation in hot locations. Hardy down to -8/-10°C once well-established, it will grow without any problem in any ordinary but well-drained soil. It can also be used as a hedge, by regular pruning, combined with other evergreen bushes such as the Portugese laurel, Elaeagnus ebbingei, Mexican orange blossom, myrtles, Pittosporum tobira, and even Grevillea. In mild climates, it can be trained as a small tree by selecting the most beautiful stem and allowing it to branch out at a height of 1.50m (4ft 11in) or 2m (6ft 7in) from the ground. The resulting specimens are particularly ornamental but require a very mild winter that will not cause them to be cut back to the ground: it would be a shame if severe frost destroyed several years of work in just a few hours! On the terrace, it will thrive in a large pot, alongside citrus trees, Grevillea, and Oleanders. This cultivation method allows the tree to be stored in a very bright, cool, frost-free room in our very cold regions.

The genus name, Nerium, is believed to have originated from its ancient Greek name, Nerion, derived from Nereus, a Greek mythological sea god. Another interpretation relates Nerium to neros, which means moist in Greek. The underlying liquid element in these two interpretations is undoubtedly explained by the fact that wild Oleander never grows very far from water. Its long roots anchor deep into the ground to draw in freshness, even on the slopes of gorges or in the beds of dried-up rivers. A testament to its incredible drought resistance, in arid regions such as the Negev in Israel or the southern Anti-Atlas in Morocco, the Nerium oleander is one of the few citrus trees, along with Acacia and Retama (a type of broom), capable of withstanding the desert, anchored in the walls of ravines.