From a botanical perspective, the oleander (Nerium oleander) is indeed highly drought-tolerant, a trait deeply embedded in its physiology. Its leaves are long, narrow, and leathery with a thick, waxy cuticle. This cuticle significantly reduces water loss through transpiration, the plant equivalent of evaporation. Furthermore, the stomata (pores for gas exchange) are often sunken into the leaf surface, creating a microclimate that traps humid air and further minimizes water vapor escape. These features are classic xerophytic (dry-adapted) characteristics that allow the oleander to conserve its internal water reserves exceptionally well during extended dry periods.
The plant's survival strategy extends below ground. Oleanders develop a robust and extensive root system that is both deep and wide-spreading. This architecture serves a dual purpose. The deep roots can tap into deeper soil moisture and groundwater sources that are unavailable to more shallow-rooted plants. Simultaneously, the widespread lateral roots are highly effective at intercepting and absorbing any light, infrequent rainfall or irrigation, maximizing water capture from a larger soil volume. This efficient foraging system allows the oleander to thrive where other plants would succumb to water stress.
When soil moisture becomes critically low, oleanders employ metabolic strategies to endure the drought. They can enter a state of reduced physiological activity, slowing down growth processes to conserve energy and water. While this may mean fewer new flowers or leaves during a severe drought, it is a survival mechanism that allows the plant to wait out the arid conditions. It is a resilient species that can withstand significant water stress and rebound vigorously once water becomes available again, rather than perishing.
It is crucial to distinguish between the water needs of a newly planted oleander and an established one, especially in an arid climate. For the first growing season, the plant requires consistent, deep watering to encourage its root system to grow deep and strong. This initial investment in water is critical for its long-term drought tolerance. Once established (typically after one to two years), the oleander's water requirements drop dramatically. It will perform well on minimal supplemental irrigation, often relying solely on natural rainfall in many arid regions, though occasional deep watering during periods of extreme, prolonged drought will promote better flowering and overall health.
