The adenium (Adenium obesum), commonly called the desert rose, growsadenium produces tubular, trumpet-shaped flowers that appear in shades of pink, white and red. A few varieties offer a sweet, pleasing fragrance. The plant produces a milky sap that is extremely toxic if ingested and can also cause severe skin irritation in sensitive individuals. Adenium shrubs grow well in U.S. Department of Agriculture zones 9 to 11.
The adenium has developed into a succulent plant to withstand the heavy rainfall of East Africa followed by the long months of drought. The plant stores large quantities of water in its stems and large base. A large, conical bulbing hump occurs above the plant's root system at soil level. From this conical formation the stems of the shrub branch outward. The shrub reaches a height of 5 feet.
The green, glossy foliage of the adenium often falls from the plant during the dry winter months. Despite the shrub's leaf loss, it never goes dormant as so many plants do during wintertime unless the temperature drops to freezing levels.
Flowers appear in clusters. The plant normally begins to bloom in late winter and continues into the summer months. Blooming is most brilliant when the rainfall is reduced. Blossoms often appear up to 3 inches in diameter depending on the cultivar.
Seeds appear in a pod known as "fruit." The fruit splits to reveal the seeds. Each seed has a hairlike structure that allows the wind to easily lift it up and carry it far for dispersal. Seeds occur only rarely due to problems in sterility. Numerous cultivars, both male and female, suffer infertility problems. Even when pollination occurs successfully there is no guarantee that seeds will be produced.
Due to the lack of viability, seed propagation is difficult. If the seeds are viable then germination is almost always guaranteed. Propagation from tip cuttings has proved to be quite successful. Cleft grafting is successful for rare hybrids but takes a great deal of skill to utilize.
The adenium requires full sunlight to thrive. It will not tolerate wet roots, so plant in a location with well-draining soil. The plant is a heavy feeder and requires regular fertilizing with a balanced plant food. The plant does successfully grow in containers.
Pests and Disease
Very few pests bother the adenium. Often spider mites will appear but are easily washed away. The plant is prone to fungal and bacterial infections. Cold weather often weakened the adenium and causes breakage to occur where fungal infections can infiltrate.