Yes, you can grow oleander (Nerium oleander) indoors as a houseplant, but it requires a specific set of conditions to thrive. From a botanical perspective, oleander is a large, flowering evergreen shrub native to the Mediterranean region, Morocco, and Portugal. This origin is key to understanding its needs: it craves abundant sunlight, warmth, and well-drained soil. Successfully cultivating it indoors means replicating these conditions as closely as possible while managing its size and being acutely aware of its significant toxicity.
For an oleander, light is not just a preference; it is a physiological necessity. In its native habitat, it grows in full sun. As a houseplant, it demands the brightest light you can provide. A south-facing window is ideal. Without a minimum of 6-8 hours of direct sunlight daily, the plant will become leggy as it stretches for light, and its most prized feature—flowering—will be severely inhibited or cease altogether. The plant's energy production through photosynthesis is directly proportional to light intensity. Insufficient light weakens the plant, making it susceptible to pests and disease. If natural light is inadequate, supplementing with a strong grow light is highly recommended.
Oleander's root system is adapted to well-draining, often sandy or rocky soils. It is highly susceptible to root rot if left in soggy conditions. Therefore, a well-draining potting mix is crucial. A standard potting mix amended with perlite, coarse sand, or pine bark will provide the necessary aeration and drainage. Watering should be thorough but infrequent. Allow the top inch or two of soil to dry out completely between waterings. During the active growing season (spring and summer), you may need to water more frequently, but always check the soil first. In winter, when growth slows, reduce watering significantly. The plant is drought-tolerant, so it is always better to underwater than overwater.
As a Mediterranean plant, oleander prefers warm temperatures. Average indoor temperatures of 65-80°F (18-27°C) are suitable. It is not frost-tolerant, which is a primary reason for growing it indoors in cooler climates. However, to encourage prolific blooming, oleander benefits from a cool dormancy period in winter. If possible, place it in a bright, cool room (around 50-60°F / 10-15°C) during the winter months. This mimics its natural cycle and promotes vigorous growth and flowering in the spring. Humidity is generally not a critical issue; oleander is quite adaptable to average household humidity levels.
Oleander is a vigorous grower and a heavy feeder during its blooming period. To support flower production, feed it with a balanced, water-soluble fertilizer every 4-6 weeks from spring through early autumn. Avoid fertilizing in the winter when the plant's growth has slowed. Pruning is essential for two reasons: to control size and to shape the plant. Oleanders can become large and woody. Prune in late winter or early spring before new growth begins. You can cut stems back by up to one-third. Always wear gloves when pruning, as the sap is toxic and can cause skin irritation. Pruning also encourages bushier growth and more flowering sites, as oleanders bloom on new growth.
From a plant's perspective, toxicity is a defense mechanism against herbivores. Every part of the oleander plant—leaves, stems, flowers, and roots—contains potent cardiac glycosides. If ingested, even in small amounts, it can be fatal to humans, dogs, cats, and other animals. This is the single most important consideration when growing oleander indoors. It must be placed well out of reach of children and pets. The sap can also cause dermatitis, so wearing gloves during any handling or pruning is strongly advised.
