Luscious trumpet-shaped blossoms 2 to 4 inches in diameter and glossy, dark green, oval leaves 2 to 8 inches long, make this native of South and Central America a handsome choice for container culture in the Pacific Northwest. They can be treated as annuals or grown indoors. Colors range from white to ruby red with several soft to bright pinks in between.
Mandevillas are a twining type of climber, so they need to be supported on a pillar or trellis or positioned against a wall. Plants may be kept at 4 to 6 feet tall, or allowed to grow to 10 feet. They require bright light and will take full sun to part shade. If the plant is kept indoors all summer and is in a south or west facing window, keep leaves and blooms away from contact with the glass, where they might burn from increased heat and light.
During the spring and summer, fertilize every two weeks with a 20-20-20 liquid fertilizer or alternate a 20-20-20 with a 10-30-10. Regular waterings during this growth period should be followed by a slight reduction of water during the winter. Keep in mind that plants in large containers may retain moisture in the middle of the root zone, and/or at the base of the plant, even though the top seems dry. Mandevilla should never run completely dry, nor should it remain in soggy soil.
In fall and winter especially, set the plant on a humidity tray. Mandevillas are not frost-tolerant. Ideal temperatures are 60-65º F at night and 68º F and above during the day. Don’t let them get below 46º F. Pinch to encourage fullness in early spring and prune back in the fall. Mandevilla is attractive to birds, bees and butterflies.