Yes, you can grow oleander (Nerium oleander) indoors as a houseplant, but it requires a significant commitment to replicating its preferred Mediterranean environment. From a botanical perspective, its success hinges entirely on how well you can meet its specific needs for light, temperature, and humidity, which differ considerably from the average indoor setting.
As a plant adapted to full sun environments, the oleander's photosynthetic machinery is calibrated for high light intensity. Insufficient light is the primary reason indoor oleanders fail. They will become leggy, with elongated stems and widely spaced leaves as they stretch for a light source. Flowering will be non-existent or severely reduced, as bud formation is directly triggered by abundant light. To thrive, an indoor oleander must be placed in your sunniest possible location, ideally a south-facing window that receives several hours of direct sunlight daily. During the darker winter months, supplementing with a strong grow light is often necessary to maintain health.
Oleander plants expect a cycle of warm summers and cooler winters. They are not true tropical plants that require constant warmth year-round. During the spring and summer growing season, they enjoy room temperatures between 65°F and 80°F (18°C - 27°C). To set buds for the following year, they benefit from a period of winter dormancy. This involves moving the plant to a much cooler (but frost-free) bright location, such as an unheated sunroom or garage with windows, where temperatures are maintained between 40°F and 50°F (4°C - 10°C). This cool rest period is crucial for conserving the plant's energy and promoting prolific flowering in the subsequent season.
The dry, stagnant air typical of most centrally heated or air-conditioned homes is a challenge for oleanders. While they are relatively drought-tolerant in the landscape, indoor dry air can lead to stress, making the plant more susceptible to its primary indoor pest: spider mites. These pests thrive in dry conditions and can quickly infest an oleander. To combat this, increasing ambient humidity is essential. This can be achieved by regularly misting the foliage, placing the pot on a pebble tray filled with water, or using a room humidifier. Good air circulation, provided by a gentle fan, also helps strengthen stems and discourages pests and fungal issues.
Oleanders require a well-draining potting mix to prevent root rot. A standard potting soil amended with perlite or coarse sand works well. Their watering needs fluctuate with the seasons. Water deeply and thoroughly during the active growth period, allowing the top inch of soil to dry out between waterings. During their winter dormancy, water much more sparingly, just enough to prevent the soil from completely drying out and the stems from shriveling. Feed with a balanced, water-soluble fertilizer every 4-6 weeks during the spring and summer, but cease all feeding during the fall and winter dormancy period.
From a plant defense perspective, oleander produces potent cardiac glycosides throughout all its tissues—leaves, stems, flowers, and sap. This is a highly effective evolutionary trait to deter herbivores. In a home environment, this translates to extreme toxicity to humans, dogs, cats, and other pets. Ingestion of any part of the plant can be fatal. This must be the primary consideration before introducing an oleander into your home, especially in households with curious children or pets. Always handle the plant with gloves, particularly when pruning, as the sap can also cause skin irritation.
