Like Oleanders, Adenium is a member of the Dogbane family (Apocynaceae) They are native to the deserts of South and East Africa and the Arabian Peninsula. Since they are considered to be a tropical plant in Central Texas, the plants should be grown in pots so that they can be brought indoors in cool weather.
Young plants should be grown in filtered sunlight, outdoors, in pots under a sparsely branched tree, or at the edge of a canopy of a more densely branched tree. Larger plants, such as those in 10” pots or larger, will tolerate full sun, but will also do well in light shade.
Adenium is a succulent plant that stores water in its stems and branches. The swollen base of the plant is used as water storage and is known as a “caudex”. During the growing season, allow the soil to dry slightly between watering. When the temperatures start to fall, Adeniums will drop their leaves. They may be overwintered in the house in a bright location. Since the plant is dormant, watering during the winter will be infrequent. A 6” plant may need watering once a month, a larger pot perhaps not at all!
As temperatures warm in the spring, and new leaves emerge, regular watering should resume. This should occur around April in Central Texas. At this time, the night time temperatures should be warm enough (above 70 degrees F) to move the plant outdoors again.
During the growing season (April-October), fertilize Adeniums monthly with a low Nitrogen fertilizer with micronutrients, such as Fox Farm Tiger Bloom. Flowering generally begins in late winter to early spring, sometimes before the leaves begin to appear. The Adeniums vary on length of flowering by variety, but generally will flower continually, with the exception of the hottest part of the summer.
Adeniums require a well-drained potting soil, and tolerate being root bound very well. Avoid “over-potting”, and when repotting is necessary, shift only to the next largest pot size.
Adeniums are occasionally plagued by mealy bugs and spider mites. Treat them with an appropriate insecticide when they first appear. Safer insecticidal soap has worked well on my Desert Roses, as does gently washing the insects off with water. Alcohol on a Q-tip may also be used to dab on mealy bugs to kill them.