Oleander are one of several flowering shrubs that will grow well indoors. According to Dave Robson at the University of Illinois, oleanders need large amounts of bright direct or indirect sunlight and warm ambient temperatures to bloom profusely indoors. Moisture control, drainage and regular applications of a gentle fertilizer round out the main care criteria.
Provide a brightly lit growing location within 5 feet of a window. Ensure that your oleander receives at least three to five hours a day of bright direct sunlight or a full day of very bright indirect light. Uncovered north facing windows are ideal, as are lightly screened south and west facing windows.
Maintain ambient temperatures around your oleander above 50 degrees Fahrenheit and below 80 degrees Fahrenheit for optimal performance and to prevent cold damage or leaf burn.
Water your indoor oleander sufficiently to keep the soil evenly moist but not continuously soaking wet. Empty the saucer of water after each irrigation session and do not let the roots stand in water.
Fertilize with a slow release, balanced houseplant formula with a guaranteed analysis of 10-10-10 or 20-20-20. Apply several times a year according to the product label dosing directions, and water in well after each feeding.
Prune away and discard any dead, discolored or damaged leaves when you spy them. Wear gloves to protect your hands from the milky latex plant sap, as it can be irritating to the skin.