Allamanda cherishes moisture and needs watering in case of heat waves. But don't forget that the root area must drain well or the roots will rot! The allamanda vine has particularly high water needs during the 1st year after planting. Water preferably in the evening.
Fertilizing Allamanda cathartica is best with a liquid water-soluble plant food once every two weeks during active growth. Do not give too much fertilizer to avoid overcrowding of foliage and lesser flowers.
This tropical plant needs warm conditions with day temperatures of 70ºF (21ºC) or higher and night temperatures of 60-65ºF (15-18ºC). Providing quick, long-season color, Allamanda can be planted outdoors in the mildest climates. Elsewhere, it will happily reside in a container to be moved indoors in cold weather.
If you live around the Mediterranean, plant it in spring in light soil. It needs a lot of sun to develop well. It loves soil that drains particularly well. It'll thus feel right at home with a mix of one part garden soil, one part soil mix and one part sand.