From a botanical perspective, *Nerium oleander* is a large, evergreen shrub native to the Mediterranean region, adapted to full sun, warm temperatures, and well-draining soil. Its fundamental nature is that of an outdoor plant. However, with a significant commitment to replicating its ideal conditions, it is possible to grow oleander indoors. It is crucial to understand that this is a containment strategy, not its preferred state. The plant will always strive to be larger and more robust than an indoor setting typically allows. Furthermore, all parts of the plant are extremely toxic if ingested, so this is a critical consideration for households with children or pets.
Light is the most critical factor for indoor oleander success and the primary reason many attempts fail. As a sun-adapted species, its photosynthetic machinery is designed for high-intensity light. A sunny windowsill is the absolute minimum requirement. The plant demands a minimum of 6-8 hours of direct, unfiltered sunlight daily. An unobstructed south-facing window is ideal; east or west may be sufficient but often falls short. Without this intense light, the plant will become leggy as it stretches for a light source, fail to produce its characteristic blooms, and become increasingly susceptible to pests and disease. In darker winter months or in less-than-ideal exposures, supplementing with a full-spectrum grow light for 12-14 hours a day is often necessary to meet its metabolic needs.
Beyond light, the plant's health depends on replicating other aspects of its native habitat. For temperature, oleander prefers warmth. Average indoor temperatures of 65-80°F (18-27°C) are suitable. It can tolerate cooler temperatures down to 50°F (10°C) in winter but will suffer if exposed to drafts or freezing conditions. Humidity is another key factor. Indoor heating and air conditioning create very dry air, which can stress the plant and attract spider mites. Increasing local humidity through a pebble tray filled with water or a nearby humidifier is beneficial. Good air circulation around the plant also helps deter pests and fungal issues.
Oleander's watering needs are a balance between its Mediterranean drought-tolerance and the constraints of a container. The goal is to avoid both prolonged drought and soggy soil. Water deeply when the top 1-2 inches of soil feel dry to the touch, allowing water to flow freely from the drainage holes. Then, allow the soil to dry out somewhat before watering again. Soggy, waterlogged soil will quickly lead to fatal root rot. For nutrition, oleander is a heavy feeder, especially when container-bound. During the active growing season (spring and summer), feed with a balanced, water-soluble fertilizer every 4-6 weeks. This supports both vigorous vegetative growth and the high energy demands of flowering. Reduce feeding in fall and cease entirely in winter when growth slows.
To maintain the plant's form and health, annual pruning is recommended. The best time to prune is after the main flowering period. This encourages bushier growth and more blooms for the following season, as oleander flowers on new growth. Always wear gloves when handling the plant due to its toxic sap. Repotting will be necessary every 2-3 years or when the plant becomes root-bound. Use a well-draining potting mix, perhaps amended with sand or perlite to improve drainage. When repotting, it is an opportune time to inspect the root system and prune away any dead or rotting roots.
