Plant oleanders in a sunny location in spring or autumn, and water the plant immediately. For best results, plant oleanders in the evening to allow the plant time to adapt before it is exposed to bright sunlight. After planting, watering isn't necessary unless it is very dry. To promote flowering, use a nitrogen-rich fertilizer in spring. When planting or caring for oleanders, wear long-sleeved clothing and gloves to prevent irritation caused by touching the plant.
When choosing a fertilizer, opt for one that is low in phosphorus. In droughts, provide the plant with 1 to 2 inches of water weekly. Oleander grows well in partial shade but flowers more abundantly in direct sunlight.
For maximum growth, amend the soil with compost and peat moss before planting oleander. If the plant is in a container, move the container indoors when temperatures reach 32 degrees Fahrenheit. To repair damage caused by freezing temperatures, prune away dead branches in spring when new growth appears.
Perform annual pruning in the autumn by cutting away dead or diseased branches and excess growth. Every third year, prune large, woody branches back to further control growth. When growing dwarf oleander, deadhead the flowers after they bloom. Do not compost any part of the oleander shrub, as all parts of the plant are poisonous.