|Official Plant Name||Nerium oleander|
|Common Name(s)||Oleander, Nerium|
|Native Area||Mediterranean, North-West Africa, India|
|Hardiness Rating||H2-H5 (depending on variety)|
|Flowers||Commonly shades of yellow, pink, white or red|
|When To Sow (Indoors)||March, April, May|
|Flowering Months||July, August, September, October|
1 – 2.5M
1 – 1.5M
July – October
Most Fertile Soil Types
Moist but well drained
Oleander is a storied and reputed plant – it is mentioned in ancient writings, depicted on Pompeii’s frescoes, and is a recurring motif in sensationalistic novels, in which it is typically portrayed as a poison!
Poisonous it may be but this evergreen bushy plant is low-care, floriferous, and blooms throughout summer. It produces gorgeous flowers in colours from pure white to blood red.
Tough and tender – that cliched phrase perfectly describes Oleander.
Oleander can tolerate urban jungle heat and is even drought-tolerant to an extent. And it can make do with poor soil and heavy soil. That’s plenty tough.
However, it very tender – frost tender, that is. This tough-tender plant doesn’t have to deal with much frost, though, in the regions of the American South where it is so prevalent. And all its varieties are terrifically beautiful – as terrifically beautiful as they are terrifyingly toxic. Some plant!
Plant life how-tos always include a paragraph along the lines of “How to care for Carnations” or “Gerbera care and tips”, but with Oleander things are a little different. This truly beautiful flowering plant is so remarkably low care and low maintenance but is so poisonous that it would be more meaningful to include a heading like, “How to Care for Yourself from Oleander”!
Properties of Oleander
Oleander is an evergreen shrub that can be short and ‘shrubby’ or develop a woody stem and grow up to a fair height so that it looks like a small tree. Dwarf cultivars settle at only one to two metres. The intermediate ones reach heights of 2.5 to 3.5 metres.
The cultivars that grow into small trees can attain heights of up to around 7 metres. Almost all of them have bushy, open habits and almost all of them are profuse bloomers and flower right from the beginning of summer, sometimes even before, to the end of summer.
The leaves are long and lanceolate, usually of a slightly greyish deep green hue. They are either opposite or are borne terminally in threes.
The showy flowers are usually single but some cultivars bear double flowers. They are about 5 to 7.5 centimetres wide. Single flowers have five petals or lobes with the flowers of many cultivars exhibiting overlapping or imbricate corollas. Also, the petals of the single flowers are often curved or curled in one direction, bringing to mind a pinwheel.
Their colours include white, cream, all shades of pink from pale delicate pink to vibrant magenta pink, and deep rich reds.
Oleander belongs to Genus Nerium, which includes a species count of just one! The sole species is Nerium Oleander. The plant’s floral beauty has led it to be cultivated to quite some extent, in spite of its poisonous characteristics, and more than 200 cultivars are known.
Background and Origins
Oleander’s showy, salver-shaped or funnel-shaped blooms have a very tropical look about them. They’re flowers you’d expect to see blooming in Tahiti; they’re something you envisage decorating a Hawaiian hula dancer’s bodice.
In fact, Nerium Oleander is native to a narrow but wide belt of land from Iberia and France through the Mediterranean and Persia to India. It is also native to North-West Africa.
Notwithstanding Oleander’s toxicity, it has been cultivated for millennia. It was known to the ancient Greeks and also the ancient Egyptians. Descriptions of Oleander occur in ancient Greek texts dating from 400 to 180 B.C. including the writings of the renowned philosopher Theophrastus.
That it was a very popular flowering plant in ancient Rome is inferred from its appearance on quite a few frescoes in the villas excavated at Pompeii.
Half-a-dozen varieties are outlined underneath with an eye to including a diversity of heights and spreads, and a matching diversity in floral shapes, forms, and colours.
‘White Sands’ has a bushy but dense habit and grows to approximately 1.5 metres with about the same spread. It is even less frost-hardy than most other varieties but it is very floriferous and has a relatively extended blooming season, flowering from before summer to after summer.
It bears the loveliest of pure white flowers with those appealing ‘pinwheel’ style petals.
‘Petite Salmon’ has an odd name – for an Oleander, the plant is indeed petite at only about 1 to 1.8 metres and with the same spread, exhibiting a bushy, dense habit, but there is nothing salmony (or otherwise fishy) about its colour, scent, or anything else. The salver-shaped flowers are ‘pinwheel petalled’ and are in a delicate tone of baby pink.
‘Twist of Pink’ delivers a twist on the foliage too. The leaves are variegated, displaying irregular but striking yellowish vertical stripes. This cultivar bears double flowers in a deep, saturated pink, and it is the ruffled pink petals that give the plant its name. It reaches an ultimate height of just over two metres. It is a very popular variety on the other side of the pond.
‘Splendens’ is an intermediate size cultivar, reaching a height of 3 to 3.5 metres with about the same spread. It has a bushy habit, often vase-shaped. It bears bowl-shaped double flowers of a particularly neat and symmetrical form. They are of candy pink hue and have a satiny lustre.
‘Calypso’ is a ‘tree-sized’ Oleander as it reaches an ultimate height of 4 to 5 metres with a spread almost as wide as its height. It is heat tolerant, even for an Oleander. It produces single, very full, salver-shaped flowers of an intense, eye-catching magenta-pink hue. This variety is especially popular in Florida and Southern California.
‘Hardy Red’ indeed lives up to its name because it is hardy, at least by Oleander standards, being hardy to Zone H5. This variety is another large one, attaining a height of up to 4 metres with a spread of about 3. This is one of the most attractive of all Oleanders because of its showy flowers. They are single, funnel-shaped, and of a riveting blood-red colour.
Habitat and Growing Conditions
Oleander’s habitat and growing conditions are predominantly in mild Mediterranean climates near streams and other waterways, including coastal areas. It prefers full sun or at least part sun locations.
It cannot withstand freezing conditions or even frost as most cultivars are hardy only to Zone H3, but it is not particular about anything else. They grow in any old soil and any old pH, including Strongly Acidic. However, the best pH for these plants is between 6.1 and 7.5.
Though the large majority of cultivars are hardy to Zone H3, a few are hardy only to Zone H2. A few, on the other hand, are frost-hardy and suitable for growing in Zones H4 and H5.
Having been introduced to the Far East, it now grows wild in several of that region’s countries.
This is one shrub whose list of habitats can rightfully include ‘highways’! Oleander is well known to be widely used for erosion control and beautification by the highway departments of America’s two most populous states, California and Texas.
Varieties are planted along the medians and the sides of highways. They don’t need much care or maintenance, poor soils and heat don’t deter them, deer let them be, and children and pets do not wander along highways. Smart chaps, those American highway department blokes!
Where to Plant Oleander
The first rule is “Where children or pets cannot get at this very poisonous plant.”
That important heads-up out of the way, most residents of the United Kingdom will not be able to plant this frost-tender plant outdoors. Except for those fortunate enough to be living in balmy (relatively speaking) regions of the UK, most gardeners will perforce need to grow Oleander in a pot, container, or planter so that it can be overwintered indoors.
Oleanders make wonderful patio and deck plants. As long as they get at least several hours of sun they’re great for the balcony too.
A good-sized container or planter with an Oleander can fill any vacant spot in your garden with a gorgeous flowering plant.
If you live in a secluded area by the sea in a mild part of the country and have no children or pets, and would like to build a windbreak or plant a decorative flowering bush, your jackpot is soil-indifferent and sea spray-tolerant Oleander in all its cultivars. Plant one, plant all.
Feeding, Care and Growing Tips
Though Oleander is an evergreen shrub, the hardiness of most cultivars is only to H3 which means that they cannot be grown outdoors in any but the warmest coastal parts of the United Kingdom, such as a small region in the south-west and another tiny region in East Anglia. At least this salt air-tolerant plant is very amenable to growing by the sea.
In the vast majority of regions of the UK most Oleander varieties have to be kept as a container plant so that they can be overwintered indoors, or they have to be grown in a greenhouse.
However, you can search for a hardy variety, such as Hardy Pink and Hardy Red, and confidently grow these outdoors in your garden, though in a sheltered location, almost anywhere in the United Kingdom.
Oleander can be started indoors from seeds in early spring. Growing Oleanders from cuttings is much easier than most other plants so you could also start them from cuttings in early to mid-spring.
Seeds may be started in a tray or in small pots. Either way, they should be sown in a sterile potting mix. Dampen the potting mix and just lightly dab in the seeds, about three to a pot. Seeds need light to germinate so they should not be covered. The lightest of sprinklings of the mix will suffice.
Oleander seeds germinate after a comparatively long time – 15 to 20 days – so it will help if the conditions are as favourable as possible. First, the soil temperature should stay around 20° to 21° centigrade. Next, cover, but do not seal, the pots with cling film or shrink wrap. Finally, keep watering the seeds but very lightly so that the potting mix stays just damp.
As soon as the seeds germinate, remove the cling film and put the pots on a sunny windowsill or where the seedlings can get several hours of direct sunlight. If you started them in trays, transplant seedlings each to its own pot after they have developed two pairs of true leaves. If you started them in individual pots, thin as necessary or transplant.
When growing from cuttings, take a cutting from a mature greenwood stem. Cut off a 15- to 20-centimetre cutting just underneath a leaf node. Remove the basal leaves and retain about four near the top of the cutting. Put it in a small jar of water so that the water level is between one-third to one-half of the way up the column.
Place the jar on a windowsill where the cutting can get several hours of indirect sunlight. Change the water about every three days. In seven to ten days the column will put out roots. When the roots are 3.5 to 4 centimetres long, it is time to put the nascent plant in a small pot. Put it in a place where it gets several hours of direct sunlight. Water in moderation.
Whether your plant is from seed or cutting, keep potting up as necessary. When you do so in a large container, the planting hole’s width should be twice as wide as the hole is deep. Be sure that the roots are spread out naturally and are not clumped.
The soil level in the new container should be at the same point that it was in the previous pot (which should be right at the base of the stem). While transplanting, lightly water the plant and keep the soil moist.
After a year to eighteen months, the plant can be transplanted into its last appropriately-sized container as indicated by the eventual height and spread of the variety. An Oleander, depending on the ultimate size of the variety, may be grown in a pot, container, or planter.
A halfway decent mixed loam amended with some compost will work very well for Oleander. It should drain well – overly wet soil or waterlogged soil is a big no-no for Oleander.
In spring, after there is no danger of frost, the plant can be shifted outdoors. It would be wise to harden it for a week to ten days first.
In the UK, Oleander should be placed in full sun. In most regions of the UK a mature Oleander plant’s water needs will be met by rain. During dry periods you will need to water it, though moderately.
Avoid letting the soil stay dry for more than a few days. Though Oleander is drought-tolerant, lack of water will affect flowering. Oleander does not care to be over-watered and should this happen, it will give you a signal: yellowing and yellowed leaves.
Before winter sets in, bring the plant back indoors. Put it in a place where it gets at least a few hours of sunlight. Though Oleander is evergreen it goes dormant in winter and so should be watered only sparingly during this time.
If you have acquired one of the few frost-hardy cultivars and transplanted it outdoors, be sure to mulch around the plant in winter. If you are in a particularly cold part of the country, consider covering up the main stem from the base with horticultural fleece.
Come spring, start reintroducing the plant to the outdoors in a process of ‘re-hardening.’ In conjunction, gradually increase the quantity of water.
If you have mulched an outdoor plant, remember to remove the mulch in spring.
Although Oleander does well without any fertilising, if you wish you could feed it with a small quantity of 10-10-10 in mid-spring, in either liquid or slow-release form. Otherwise give it a helping of compost.
Pruning Oleander is strictly an optional exercise but can be a highly beneficial one.
As the plant grows and puts out shoots and stems, pinch off limited young stems to prompt more branching and bushier growth.
During the flowering season, you can deadhead to promote continuous flowering but even this is not essential as deadheading does not have much of an impact on Oleander.
After the flowering season is over, in mid-autumn the plant can be trimmed for size and shape.
Oleander is Poisonous
Oleander itself is a recurrent object in sensationalistic romances and thrillers. But, no, this lovely flowering plant is seldom used to signify beauty, let alone romance. It is usually used merely as a poison!
Oleander’s bad rap has put it on the way to displacing old-fashioned arsenic and hemlock as the modern writer’s research-free poison of choice.
But that’s only because Oleander really is so poisonous – make that so extremely poisonous. Consuming even a small amount of any part of Oleander can result in, and has resulted in, death. You can’t even touch the plant without risking breakouts on your hands and arms.
When handling Oleander you are strongly advised to wear long gloves and long sleeves. When pruning the plant do not let the (toxic) sap touch any part of your skin or body.
One can’t be too emphatic about this. If children and small animals have access to, or can enter into, your garden then Oleander has no place in it. You could grow it in a locked greenhouse, though.
This plant contains various cardiac glycosides from the base of the main stem to the petal on the flower. What they do upon ingestion is bring about lethargy, nausea, vomiting, fever, diarrhoea, bloody stools, visual disturbances, dizziness, fainting, arrhythmia, bradycardia . . . that’s scary enough.
If any child, pet, or person is suspected of having ingested the smallest amount of Oleander, immediately call an ambulance to transport him/her to a clinic or a hospital, and in the meantime give him/her fluids, such as a rehydrating solution, to keep sipping.
Common Diseases and Problems
Oleanders are generally very pest-resistant and disease-free, especially if they are kept outdoors.
If these plants are grown in a greenhouse, they may be subject to attack by glasshouse red spider mite and, less frequently, by scale insects and mealybugs.
Indoor plants are more susceptible to scale insect infestation, and also to red spider mite and aphids to a lesser extent.
You can avoid these problems by keeping indoor plants in rooms that are not heated and that have good air circulation, such as provided by free-standing fans.
Where to Buy Oleander
Oleander is a remarkably beautiful flowering evergreen yet its varieties are not as widely available in the UK’s garden centres and online stores, as one might expect.
The reasons are that this evergreen is not frost hardy, and, more critically, it is very poisonous.
Even so, it is perfectly possible to find several varieties, especially online, at a limited number of nurseries and merchants. What’s more, you can buy Oleander as seed, young potted plants, or in bare-root form.
Kersie learnt the basics of gardening as a toddler, courtesy of his grandfather. In his youth he was an active gardener with a preference for flowering plants. He is a professional and vocational writer and his freelance projects have spanned various kinds of writing.