Adenium: The Beloved Desert Rose
BY TYSON CURTIS
Grow an Adenium. Here’s what they need to thrive:
A warm room is essential. Adeniums don't want the temperature in their habitat to dip below 65 - 70 degrees Fahrenheit.
A few hours of direct sun—more is better, but not within one foot of a window, or you risk burning the caudex.
During summer, let the surface of the soil dry out, but don't let it dry deeper into the pot (standard houseplant watering).
During winter, water Adeniums like cactus—totally dry between waterings.
Cactus mix!
Typical (all-purpose) houseplant fertilizing when actively growing during the summer.
If your plant is Adenium socotranum, it will want to grow during the winter, so the care instructions should be flipped around to encourage winter growth.
READ ON to learn more about these fascinating plants, their natural habitat, and how to care for them in your home!
Adeniums are beloved by plant lovers from surprisingly different backgrounds. Their abundant blooms give them the common name Desert Rose, though their flowers look closer to an oleander, with whom they share distant relations. These flowers are everblooming when in growth, a rare feature sought out by houseplant growers. Adeniums have a sculptural caudex, making them beloved by caudiciform collectors and those who love oddities. Succulent collectors embrace them as their own. Even bonsai growers are enthusiastic about their treelike form and ability to adapt well to very small pots.
Adeniums grow naturally from the deserts of Africa through the Arabian Peninsula and even on the mystical island of Socotra. In these arid regions adeniums receive summer rain and evolved their caudex to store water during a dry winter rest. Losing their leaves at this time also helps conserve moisture. In habitat they often bloom in spring, before their leaves flush; there is little more awe-inspiring than a massive weathered adenium, leafless and in full bloom.
Across the vast range of their habitat, it’s not surprising that many separate adenium species evolved, each with its own unique flair—and those are just the naturally occuring forms, there are many more hybrids. Adeniums germinate easily and grow quickly from seed. This allows horticulturists to select for the brightest red, or darkest purple flowers, quickly creating hybrids far outside of naturally occurring flower colors. Many flowers have multi-colored hues. They’ve even coaxed adeniums to grow double flowers! This work was originally captained by Mark Dimmitt from Tucson, Arizona, but later taken up by Southeast Asian growers when they realized that, against all odds, these desert roses wouldn’t rot in their humid wet climate, since it was so warm. Furthermore, in Southeast Asia adeniums don’t present their typical yearly dormancy; instead they grow year-round, with only a winter slowdown, making hybridization even faster.
Another boon for adenium growers is that they take well to grafting, meaning that once a grower has hybridized desired characteristics, they can take cuttings from that pinnacle plant and graft them onto regular adenium stock, keeping the desired characteristics consistent. Occasionally you’ll even see multiple flower colors grafted onto one plant. Only recently have these decades of careful selection finally reached the public in the form of many new and exotic hybrids.
ADENIUM CARE
These plants are from warm areas that have wet summers and dry winters. As such, they won’t live outside unless you are in the most southerly and protected parts of California, such as San Diego. They like a sunny warm room indoors or a greenhouse. This really can’t be stressed enough. They love warmth! Adeniums prefer some direct sunlight, though if you put them within a foot of a window their caudex is likely to burn, causing unsightly damage that is long-lasting.
Adeniums want average houseplant watering during the summer, having the top layer dry out but otherwise retaining moisture in the soil. Don’t let them go dry at this time, as their growth will stall, followed by defoliation. During the fall, especially if your room cools down, most adeniums will drop their leaves. It’s best to cut back watering at that time and treat them like a cactus, only watering after they have been dry for a while, and only half-saturating them when you do water.
It is possible to have a room with ample light and warmth for year-round growth, as they do in Southeast Asia. If your plant seems inclined to keep growing in the fall, follow its lead, cutting back water in winter, but not entirely. During the spring, when you see new growth, slowly increase watering again. Overwatering during dormancy is the number one way to kill your adenium. Adeniums like a gritty cactus mix that is free-draining. When you re-pot them, you may choose to lift the roots an inch or two, exposing the swollen and sculptural root system over time. Most adeniums grow sparsely branched and upright. Some growers opt to cut back their growth by a third in early spring to encourage branching and a more umbelled canopy. Some growers even wire their branches. Adeniums appreciate food when in growth and should be fertilized with all purpose fertilizer. This will help with vigorous growth and abundant blooms.
Since there are too many hybrids to comprehensively list here, we’ll focus on describing just some adenium species, though they are often hard to find on the market.
Adenium obesum. Many of the variants you’ll see are nestled under A. obesum, and if you are purchasing a generic adenium it’s likely A. obesum. A. obesum has a large range, from Mozambique through Kenya and across the semi-arid desert where the Sahara drifts off into northern Africa. Flowers tend to be red or pink. They can get very large, as the name implies, in habitat.
Adenium obesum var. Somalense. From Somalia, this plant develops a single large subterranean caudex that can be raised, but be suspicious if you see one with this form for sale, as poaching is rampant in the trade. This adenium is beloved for its thin, shiny, dark, patterned leaves. A. obesum var. Somalense is particularly fussy about dry winters. The flowers are pink, but with lighter patches, giving it a multicolored pink and white look. It can get quite massive in habitat.
Adenium obesum var. Socotranum. From the island of Socotra. This is one of the most sought-after adenium for collectors, due to its naturally upright form and rarity. They can grow a single trunk for many years before branching out, much higher than other adeniums. In fact, this form is so desirable that many growers will train other A. obesum in the ‘Socotranum’ form, pruning them low and forcing upright stature. Don’t worry, though—it will still develop a stout trunk over time. A. Socotranum is the only adenium to prefer winter growth, usually leafing out in later summer or early fall, though it still needs warmth at that time. It goes dormant with summer heat. Very large in habitat, up to eight feet in diameter! Unfortunately in cultivation this adenium is slower than most.
Adenium arabicum. From the Arabian Peninsula, this adenium naturally grows with a squat habit, not having the typical taper or tall upright branches of most adeniums, making it highly desired for collectors. Roots form horizontally from the base of the plant, growing in a clean repetitive pattern, making them excellent candidates for elevation. The glossy leaves are shorter and wider than many adeniums. Flowers are pink.
Adenium boehmianum. From Namibia and Angola, known as “bushman's poison,” as the plant contains toxins used by the San people to tip their poison arrows. This adenium grows a tall tapered caudex and is shy to leaf in the dry Namib desert. The leaves are the largest of all adeniums, dull and grey in color, feeling slightly fuzzy to the touch. The flower is also muted, being dull pink with a dark ruby red center. Habitat plants are medium in size, still larger than a person. This adenium is one of the most cold-hardy, and growers have success in Southern California using it as a landscape plant.
Adenium swazicum. If you’ve ever been to Kruger park in South Africa, hopefully you kept a keen eye on the stoney outcrops there, as this adenium grows there. Its range pushes from Kruger south into Swaziland (now Eswatini) giving this plant its specific epithet. It has a hot pink flower and is multibranched, making a single large subterranean caudex in nature, not having the characteristic twisted roots directly below the surface. Habitat plants tend to be on the smaller size, for adenium. This adenium is also one of the most cold-hardy, and growers have success in Southern California using it as a landscape plant.
We carry many different varieties of Adeniums at Flora Grubb Gardens, and we grow them all ourselves down at Grubb & Nadler Nurseries in the Rainbow Valley. Come see us and bring one home!
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