Adenium Obesum

Botanical Name — Adenium obesum

Common Name — Desert Rose, Sabi Star, Impala Lily, mock azalea

Plant Family — Apocynaceae

Background

Adenium obesum is native to the tropical and subtropical regions of Eastern and Southern Africa and the Arabian Peninsula. Desert rose plants prefer warm temperatures and moderate moisture levels, becoming deciduous during periods of drought or extreme cold.  These slow growing plants can reach up to four feet tall though this can take decades. Thick stems and a stout swollen caudex, as well as springtime displays of bright colorful flowers make Desert rose a striking beauty. Though lovely to look at take great care when handling this plant. Adenium obesum contain a sap so poisonous that it has been used as arrow poison by hunters throughout much of Africa.

Growth Requirements

Sun

• Desert rose plants do best in full sun, ideally 5 to 8 hours a day.

Temperature/ Humidity 

• These plants thrive in warm temperatures. They are rather heat tolerant and will do well in temperatures that would be too harsh for many other plants. 
• They’ll thrive in temps from 70 degrees to a scorching 100, making them perfect for the outdoors during the spring and summer, or a sunny window sill all year round.  
• As the weather starts to cool keep these plants indoors, and avoid temperatures below 50 degrees fahrenheit. 

Water

• Water regularly during the spring and summer months, allowing the soil to dry out completely in between watering. Though these plants can withstand some drought, more frequent watering is necessary to produce blooms. 
• It is better to err towards underwatering. Desert rose plants are extremely drought tolerant, storing reserves of water in their thick caudal trunk. Overwatering will quickly lead to root rot and is the easiest way to kill these semi-arid plants. 

Soil/Roots

• Desert rose plants like a nutrient rich soil that is fast-draining and well-aerated. Compost is an excellent amendment for supplying the soil with additional nutrients. 
• Use a soil mixture that is formulated for cacti or succulents, or amend regular potting soil with equal parts pumice or sand to ensure the mixture is well-draining and not too dense. 

Flowering

• When grown under ideal conditions desert rose plants blossom brightly colored, trumpet-shaped flowers. Blooms last for several weeks and can be red, pink, white or yellow.
• Typically these plants will undergo a dormancy during the peak of summer. As a result these plants will experience two periods of bloom: once in early spring, and again in early autumn. 

Fertilization

• Fertilization is not necessary for these plants but can encourage blooming. Use a water soluble fertilizer, diluted to half strength. A balanced, or phosphorus-rich fertilizer is ideal to encourage flowering. 
• Outdoor plants should be fertilized two to three times during spring and summer, while indoor plants can be fertilized up to once a week. Avoid fertilizing these plants in the winter.

Propagation

• Starting from seed is the most effective way to propagate desert rose plants. 
• These plants can also be propagated by stem cuttings, but these are far less likely to produce a caudex and struggle to mature over time. 

Health

Diseases

• Fungal diseases are most common and typically result from excessive moisture on foliage or roots. Treat diseases of this sort by spraying foliage with a general fungicide and pruning any unhealthy looking stems. 
• Stem and root rot are one of the most common problems encountered by desert rose plants. These are caused by fungal infection and will manifest as yellow, dark brown or black spotting along the stems or trunk. Rot can appear wet and mushy or dry. 
• White leaf fungus is another problem commonly experienced by these plants. It starts as white spotting on the leaves. Over time, leaves will turn brown and rot. If left untreated the fungus will spread down the stem of the plant. 

Maintenance (pruning, legginess, repotting)

• Little pruning is needed to maintain Adenium obesum. Prune away unhealthy looking leaves. 
• Repot during the active growth season, once the caudex starts running out of room to grow, roughly every 2-3 years. 

Toxicity

• Adenium obesum contains a poisonous, milky sap that is present in all parts of the plant. It is extremely toxic to animals and humans, and should be kept out of reach from children and pets.
• Consumption of the plant by pets will lead to vomiting, diarrhea, excessive drooling, and blistering of the mouth and throat. Topical exposure to the sap can lead to blistering and redness on the skin. 
• Take great care when repotting these plants. Always wear gloves and thoroughly wash the area if the sap comes in contact with the skin.