Gardeners looking for an exotic tropical flower would be hard-pressed to find one more unique than the desert rose. Originally from the desert regions of sub-Saharan Africa and elsewhere through the Middle East, the desert rose's wide pink striped flowers and bulbous bonzai-like trunk make it a favorite among green thumbs willing to work to help it thrive. It may require some unique cultivation to produce an optimal yield, but the intrigue and beauty that go along with this plant make the effort well worth it.
The adenium or desert rose is accustomed to the dry, sandy soil associated with its home regions. Because of that, your desert rose is most likely to thrive in a mixture of cactus soil and volcanic ash, which must be well-aerated to ensure proper drainage. Unless you live in a nearly tropical climate, you're likely to find desert roses in clay pots rather than in the ground, so that they can be brought in during the winter.
The alluring beauty of the desert rose doesn't just stem from its vibrant pink, red, or purple flowers. Its thick, bulbous trunk is similar in stature to a bonzai plant, and it can grow anywhere from two to five feet tall and one to two feet wide. The hardy trunk helps it store water, and a plump, wide stalk is an indication your desert rose is thriving. A slender, withered stem, on the other hand, tells you it needs more water. If you plant more than one desert rose, give them enough space to accommodate their mature size.
As a plant with African origins, the desert rose is used to full sunlight and high temperatures, and it will tolerate nothing less. Hardy in the warm climates of USDA growth zones 10 through 12, this plant is likely to die if exposed to temperatures below 50° F and prefers a range of 65 to 90°.
If you plant your desert rose outside, give it access to full sun, but set it where it can get a break from the high noon rays, which could scorch its leaves. If potted, bring it indoors during the cooler months, and place it near a southward-facing window where it will receive sunlight for at least 6 hours a day.
Water is scarce where the desert rose grows naturally, but when it does rain, it pours. Because of that, this plant's hydration needs vary by season. In the spring, it will need to be watered about once a week — just enough to keep the soil moist. In the fall and winter months, reduce watering to once every three or four weeks.
Remember, the thickness of the stalk is an indicator of how well-watered the desert rose is, so if the trunk is slender, give it a little more to drink — and avoid overwatering, at all costs.
Although a woody plant, the desert rose is vulnerable to a few pests. Soft and armored scale both attempt to suck the sap from this beauty, and mealybugs will consume its leaves, leaving a powdery residue behind. Neem oil or insecticide spray will eliminate both, and a solution of 1 part alcohol to 3 parts water, as well as dish soap to eliminate mealybugs, will work as well. A spray of equal parts cooking oil and baby shampoo is effective for scale.
The most common diseases that desert roses face arise from improper watering. Stem rot is caused by excess moisture, and leaf rot — resulting in yellowed foliage — happens when water is applied directly to the leaves. Treat the latter by removing the affected leaves, and the former by cutting off portions of the trunk that appear to have black or grey spots. Better yet, avoid both by applying just enough water to keep the soil moist, exclusively to the base of the plant.
The desert rose may produce more blooms if given a boost with extra nutrients, but only in its growing season. Feed it monthly through the spring and summer with a 50%-diluted liquid fertilizer, and cease feeding it completely once it's gone dormant for the winter. A phosphorus-rich diet will also yield more blooms.
Desert roses can be propagated from branch cuttings. They don't always produce as thick a trunk as the parent plant from which they were taken, but if started in a tall, thin container and moved to a wider one where their roots are open, divided portions of this stylish plant can still flourish.
Use caution when deciding where to put your desert rose, as the entire plant is highly toxic. Ancient tribes used it to make poisonous arrows for hunting, and it can cause significant damage if ingested. Symptoms may be as mild as nausea and an upset stomach, or as severe as chills, tremors, and seizures. Always wear gloves when touching the desert rose, and contact poison control if a child consumes it.
There are several varieties of desert rose, all of which possess intricate and brightly colored floral patterns. The Black Window is known for its deep purple and maroon blossoms, while the Golden Carrot's petals blaze with yellow and orange centers surrounded by radiant red tips. The Good Night variety is especially exotic, being one of the few plants to produce black flowers.