Description Light/Soil/Water Hardiness Adenium obesum subsp. socotranum is by far the largest species, reaching a height of 15 feet (4.6 m) with a cylindrical trunk up to 8 feet (2.4 m) in diameter at the base. Its large size makes it a very rare and precious species. The flowers are pink, up to 5 inches (13 cm) in diameter, and appear for a few weeks in spring while the plant is leafless. Plants may be shipped bare root   Full sun. Perfect for a sunny window. Water during the summer and spring. Reduce water in the winter, but keep hydrated enough to retain its leaves. Keep at least 50ºF (10ºC) at all times; if you keep temperatures of 60ºF (16ºC) or higher during the winter, the plant may retain its leaves. A well-drained succulent mix, with an ideal pH around 6.0 (slightly acidic). Fertilize during spring and summer with controlled-release fertilizer or liquid fertilizer according to label directions. USDA hardiness zone 10a to 11b: from 30 °F (−1.1 °C) to 50 °F (+10 °C).