Adenium obesum (2017)

By Nikki Murdick (May 2017)

Earlier this year, I was the delighted “winner” of a lovely Adenium obesum. This plant has spent the winter happily living in my dining room. It kept most of its leaves throughout the winter, although I think it will be happier still as soon as it can move outside.

This plant, often called the desert rose, can easily be found in plant nurseries or gardening centers. It is considered an easy plant to grow in temperate climates, blooming profusely and living long under good care.

Adenium obesums are noted for their thick stems or caudices with fleshy branches that are usually arranged in a spiral. The leaves are generally oval in shape and vary in size, getting larger with the age of the plant. The blooms are trumpet-shaped and come in different colors, including white and shades of pink and red.

Adenium obesum is in the family Apocynaceae and was first described as a genus in 1819. It has a large distribution: the Arabian Peninsula, including Socotra; tropical and East Africa; and now southeast Asia and the Philippines.

Over time, the number of species in the genus Adenium has been listed as anywhere from five to 12. Currently there are five accepted species: A. obesum (A. arabicum), A. boehmianum (found in Namibia and Angola), A. multiflorum (found from Zambia into Southern Africa), A. oleifolium (found in South Africa, Botswana, and Namibia) and A. swazicum (found in eastern South Africa).

The growing season for Adenium obesum is the spring and summer months. During the hot summer, they may need daily watering. Adenium obesums prefer warm temperatures above 50 degrees F, even at night and during the winter.

The plants can grow from 6 to 10 feet in height, and usually are shaped more like a bush than a tree. Adenium obesum plants grow best in well-drained, sandy or gravelly soil. They prefer direct sun, and it is suggested that the plants be rotated every two to three days to encourage the plants to grow straight, strong stems. Most websites state that this plant needs to be repotted about every two to three years, although it may need to be repotted more often.

Take care when working with this plant if there are small children or animals near, as parts of the plant are poisonous when ingested. The sap contains toxic cardiac glycosides that are said to have been used as arrow poison throughout Africa in hunting large game. Some people also have a reaction from getting the sap on their skin, so hand washing should be done immediately after working with this plant.

A. obesum can be cultivated by seeds or cuttings. In order for the seeds to germinate best, they should be left in the large seed pods until they dry off naturally. To do this, you may need to tie a bag around the seed pods to capture the seeds. Once the seeds are planted, they germinate easily, but require regular watering. Cuttings should be done using clean shears so that possible disease is not spread. Cuttings root easily during the spring and summer growing season.

Adenium obesums are prone to various pest problems. They can host spider mites and especially mealy bugs. The plants should be kept in an area with plenty of moving air, and dead plant debris should be removed immediately. Mealy bugs can be removed with a strong spray of water.

In addition, these plants can be prone to stem rot, although this is less prevalent once the plants have survived their first winter. Root rot can also be a problem, so drainage trays under pots should be emptied immediately after watering.

If you are interested in this plant, you can find more information and photos on the following websites:

Dave’s Garden – http://davesgarden.com/guides/pf/go/527
Desert Tropicals – http://www.desert-tropicals.com
Home Guides – http://homeguides.sfgate.com
National Tropical Botanical Garden – http://www.ntbg.org
Tips for Plants – http://tipsplants.com/plants/house-plants/adenium#ixzz4bzKxA5CX