Dipladenia, also known as mandevilla, grows as a tall vine with deep green foliage and large flowers. The trumpet-shaped blossoms come in shades of pink, red, white and yellow. Dipladenia grows as a tender annual in most areas, unless it's overwintered indoors in an area protected from winter frost. Temperatures below 7.22 degrees C cause the plants to die back; they must receive warmth year-round to remain perennial. The vines reach up to 30 feet tall if grown in an area that rarely receives temperatures below 7.22 degrees C.
Grow dipladenia in well-drained soil in an area that receives bright, indirect sunlight. Plant outdoor grown plants in area with dappled shade and set indoor plants near a brightly lit window but away from direct sun.
Insert a 6-foot stake into the soil at planting. Tie the vine to the stake loosely with plant ties until it begins to climb the support on its own.
Fertilise the dipladenia every two weeks with a soluble 10-10-10 fertiliser at the packaged recommended rate. Apply fertiliser from the time new growth first begins in spring until late summer.
Water the vines once weekly or when the top inch of soil dries. Provide enough irrigation to moisten the entire root ball and don't allow the soil to dry out completely.
Bring potted dipladenias indoors in fall once nighttime temperatures reach 12.8 degrees Celsius. Place the plant in a well-lit window and water as needed.
Cut back indoor-grown plants to the desired height. Remove no more than one-half the plant's height at a single trim.
If your indoor dipladenia loses its leaves, cut the plant back to an 8-inch height and store the dormant plant in a dark 55 to 60 degree location until late spring.
Aphids and other insect pests occasionally affect outdoor-grown dipladenias. Treat these pests with insecticidal soaps. Treat outdoor plants before bringing them indoors so they don't spread pests to your healthy houseplants.