Scientifically called the Adenium obesum, it belongs to the Apocinaceae family and is popularly known as Adenium, or Desert Rose. Its name seems to come from Aden, which could designate the Gulf region of the same name that gives the entrance to the Red Sea.
Native to the tropical and subtropical east and south of Africa and Arabia, it is naturally present in countries such as Sudan, Yemen, Socotra, Namibia, Zimbabwe and South Africa for example.
This article aims to guide you on the proper Desert Rose care.
Characteristics of the Desert Rose
In its natural state, the Desert Rose is a shrub or small tree reaching one to three meters high, even as an ornamental plant it is marketed as a small shrub in a pot, branched and compact, looking very exotic and with beautiful flowers.
One of the attractive characteristics of this plant is the caudex, thickening of the base of its trunk and that works as a water storage. The caudex, also known as lignotuber, is a botanical term that describes a form of stem morphology, in which it appears as a spheroid elongation or thickening, often woody.
Ornamentally, this peculiar tendency to thicken its main stem gives it a certain bonsai look. On the other hand, this condition serves to make water reserves so it can withstand periods of drought very well.
The leaves of Adenium obesum are arranged in a spiral. They are simple, whole and oval with an appreciable leathery texture that measure 5 to 15 centimeters in length and with a width of 4 to 8 centimeters, depending on the stage of development of the plant. They are semi-persistent since they usually fall in periods of drought as a defense measure against this circumstance. At those times it is said that the plant is in vegetative rest.
If cuts are made on its branches or leaves, it usually secretes a milky-looking substance (its sap) that can be irritating to the skin.
The flowers of the Adenium obesum are tubular with a length of 2 to 5 centimeters. These have five petals that together give them a size of between 4 to 6 centimeters in diameter, similar to the Plumeria and Nerium genera. They are light pink in color with a darker edge and bloom mainly in summer, although as a potted plant it can sustain much longer flowering periods.
Its seeds can be used for reproduction by sowing them during the spring and summer months.
Types of Desert Rose
Depending on the geographical area in which we are, we can find different subspecies of Adenium obesum, although some and according to experts, come to be considered their own species.
Some of the most popular Adenium obesum species are:
- Adenium obesum subsp. Boehmianum in Namibia and Angola.
- Adenium obesum subsp. Obesum in Arabia.
- Adenium obesum subsp. Oleifolium in South Africa and Botswana.
- Adenium obesum subsp. Socotranum in Socotora.
- Adenium obesum subsp. Somalense in East Africa.
- Adenium obesum subsp. Swazicum in eastern South Africa.
Cultivation of Adenium obesum in the nursery
The life of Adenium obesum in the nursery has very little to do with that of Adenium obesum in its natural habitat in Africa and Arabia, where the scarcity of water is part of their day to day, while the specimens grow sparsely through these territories.
But just because a plant is capable of living in extreme conditions, as with cacti, does not mean that in better conditions it will not develop much better. And Adenium obesum is a clear example of this.
The cultivation of Adenium obesum in the nursery, contrary to what happens in nature, is done in thousands of units, all plants grouped, in a programmed way and in different batches to be able to have commercial plants throughout all the year.
The cultivation starts from apical or interdonal cuttings, rooted in multialveolar trays or small pots that do not exceed 10 centimeters in diameter. The substrate chosen for this cultivation phase is a peaty substrate, aerated with perlite and with a pH above 6.5 and slightly fertilized. The process consists of filling the alveoli trays with this moistened substrate, cutting the cuttings from the mother plants, with a length of 4 to 8 centimeters in diameter, and planting them by burying the lower part of the cutting about two centimeters on the substrate.
The trays with the cuttings are placed on the ground or growing tables in a greenhouse with filtered light, a temperature around 22ºC and a very high relative humidity at the beginning, which will decrease as the cuttings take root.
At a professional level, these rooting greenhouses are technologically perfectly equipped with heating, shading nets and micro-sprinkler systems.
Once the cuttings are rooted and acclimatized, with a small but well-developed root system, they are transplanted to a larger pot. The type of pot will depend on the commercial size that is intended to be made, normally and in a more popular way, between 14 and 18 centimeters in diameter. The plantation substrate is less peaty with mixtures of other materials that lighten it and provide good aeration and prevent waterlogging.
The cultivation exhibition area must be very sunny and its watering periodically, without reaching excess, since it is a plant that likes to alternate a slight dryness between waterings. The normal thing is to resort to localized irrigation and take advantage of each irrigation to provide the fertilizer in small doses but frequently, with a balance 18-12-24 plus microelements.
In these perfect conditions, Adenium obesum vegetates at its maximum capacity while professional technicians and engineers control its development in perfect conditions of plant health. Depending on its formation, it is subjected to one or more pinching during cultivation to obtain more sprouted, compact and bushy-looking plants.
How to Care for Desert Rose Plant
For the cultivation of Adenium obesum in the home or garden, it is important to know certain aspects about it, such as its tropical and subtropical origin, that it vegetates with rather high temperatures, in an environment with possible droughts during certain periods of the year and that in its natural state it can reach several meters in height.
Its sale in the ornamental field is in the form of a small potted shrub, as a branched and compact plant, with an exotic appearance and with beautiful flowers. In this format, it is normal to enjoy it as an indoor ornamental plant and only in rather warm climates and without risk of frost, as an outdoor plant in the garden. Optimal temperatures for growth are above 25⁰C. Lower than 15⁰C can cause irreversible damage to the plant such as foliage fall and root rot.
Its exposure should be as sunny as possible. In poorly lit places it will lose all its leaves and may die. Inside the house it should be as close as possible to the windows and away from persistent drafts. Its waterings must be spaced apart so that the substrate is somewhat dry from time to time in order for its roots to grow healthy and strong. Let us remember that this plant has its characteristic thickening of the base of its trunk called caudex and that it works as a water storage. Too much humidity will cause the appearance of fungi that will rot their roots, fall of leaves and flowers.
The fertilizer can be of the type recommended for outdoor flowering plants, applying the lowest doses recommended by the manufacturer and spaced about 15 or 20 days between fertilization.
As the Adenium obesum is a shrub or small tree in its natural state, we have to go by pruning every four to six months for keeping a compact appearance. If, on the other hand, we plant it in the garden, we will choose a very sunny area and we can let it grow in a more natural way. We will plant it one or two meters away from other plants since with time it will acquire the characteristic size of its species. Therefore, take this aspect into account when choosing the area of your planting.
The Desert Rose prefers fresh, fertile and well-drained soils that do not get flooded. As we have already stated, it requires high temperatures and can begin to suffer below 15 degrees Celsius. If the soil or substrate is very clayey, we can improve it by mixing it with river sand and some gravel to increase its porous capacity.
As for pests, aphids or mites may appear that we must control with insecticides. It does not usually have diseases and the main enemy of this plant is excess humidity that will cause the rotting of its roots and will favor the appearance of fungi.
Propagating Desert Rose
We have already explained how to propagate the Desert Rose or Adenium obesum at a professional level. At the amateur level, the method can also be easy if it is carried out with a minimum of care.
We can choose both its reproduction by cuttings and by seeds.
Desert Rose Propagation by Seeds
The first thing is to acquire the seeds and this is not usually easy because it is not usually sold. If the plant blooms and its flowers are fertilized, they produce pod-shaped fruits that contain the seeds.
These pods, when fully mature, tend to open and disperse the seeds, an ideal time to collect them as it indicates their optimal ripening point and therefore that they are ready to germinate.
We will sow these seeds during spring or summer in trays with a special substrate for indoor plants, improving their aeration with the river sand mixture by 15 to 20%. Once the seeds are distributed, we will cover them slightly with the same substrate and water, maintaining constant humidity until germination.
We will also maintain an ambient temperature for its best germination around 25⁰C. Somewhat lower temperatures will cause a slower and more irregular germination.
When the seeds begin to germinate, we will reduce the frequency of watering and when each seedling has 6 to 8 true leaves they will be ready for transplantation to a larger pot. The planting substrate must be richer in nutrients but maintaining its porosity capacity to prevent it from puddling easily. Once the seedlings are rooted in the new pots, we can place them in full sun.
Desert Rose Propagation by Cuttings
The ideal time for their reproduction is during the warm months of the year (mid-spring to late summer). We will cut the cuttings of the healthiest plants, taking pieces from their branches seven to twelve centimeters in length.
We will immerse or smear these cuttings in the area of the cut with a rooting hormone to encourage the formation of roots. Then we will put our cutting in a pot or tray with a sandy substrate and with good drainage. We will lightly bury the cutting area and keep them protected from direct sun and drafts that can dehydrate them. If we keep the substrate moist and the environment protected with high ambient humidity, in just over 25 days, these cuttings will form new roots and thus we will obtain new plants.
As they get stronger we can transplant them into larger pots and even plant them directly in the garden.