The desert rose, known botanically as adenium, is a species of flowering perennial related to the mandevilla and oleander and is not in fact a rose. It is recognizable by its bulbous, fleshy trunk and its summer-long bloom period. It is a tender tropical plant hardy only in USDA Zones 10 and 11 but can be over-wintered indoors or grown year-round as a houseplant in colder climes.
Provide a growing location for your desert rose where it will receive bright direct and indirect sunlight or partial afternoon shade in hot climates. Ensure year-round temperatures consistently above 45 degrees Fahrenheit and move indoors immediately if temperatures dip to this point or below.
Plant in nutrient-rich but well-drained soil that is slightly alkaline in pH. Give desert rose plenty of room to spread to its mature size in its planting location, as it does not like to be disturbed once established. Provide a height clearance of at least 15 feet from overhead obstructions and at least 5 feet in width to spread.
Water to keep the soil evenly moist, but not wet, at all times. When planted in a container, provide easy drainage to prevent the roots from standing in water, which will quickly lead to rot. Do not allow the soil to dry out entirely. In warm but very dry climates this may necessitate watering every few days, while in humid climates once every 10 days may be sufficient.
Feed desert rose plants under two years of age with a complete balanced liquid fertilizer formula (such as a 10-10-10) according to label directions. Apply every two weeks beginning in the spring. In summer and fall, feed your desert rose with a slow-release granular palm food with micro-nutrients--such as a 5-2-4. Return to using the liquid fertilizer in the winter. Feed plants older than three years with just the slow-release formula several times per year according to label directions, and always water in well.