Mandevilla is a genus of tropical flowering vines native to Central and South America. They are perennials commonly grown as annuals in temperate climates because they cannot survive temperatures below 10 degrees Celsius. However, with the proper winter care, the plants can survive and thrive for many years in most climates. Mandevilla vines form flowers in a variety of colours, depending on the species, and can be various shades of white, yellow, pink or red.
Plant mandevilla vine root cuttings in spring, after the threat of frost has passed. Choose a location that receives partial shade and has well-drained soil high in organic content. Spread 1 tbsp of a high phosphorous 10-20-10 NPK fertiliser over the location prior to planting.
Dig a small hole about 5 inches deep and place the root cutting into the hole. Cover with soil and water thoroughly to bring the moisture into contact with the roots. Water once a week until the mandevilla vine has taken root and growth has emerged from the soil. Space plants at least 3 feet apart, as they can grow quite large and need room for growth.
Water mandevilla vines three times per week during spring, summer and fall. Reduce watering to once per week during winter, when the plant enters dormancy. Do not allow the soil to become soggy, or the roots will rot. Mandevilla prefers consistently moist soil while it's actively growing, but should be permitted to dry out a bit while dormant.
Fertilise mandevilla vine once every two weeks using a 10-20-10 NPK fertiliser. Use half the amount directed by the manufacturer or the plant will focus on growing foliage rather than flowers. Water thoroughly before and after applying to release the nutrients into the soil. Never allow the fertiliser to come into contact with the plant, or root burn can occur. In winter, no fertilisation is required, as the plant is dormant and will not absorb the nutrients.
Mandevilla vines may be brought indoors during winter, or they can be allowed to die in the garden. If you choose to overwinter indoors, remove the soil from around vines carefully, without causing any damage to the roots. Continue until the entire root system is exposed. Fill a container several inches wider in diameter than the root system with a soil comprised of one part peat moss, one part sand and one part potting soil.
Form a hole in the middle of the soil mixture, place the mandevilla vine inside and recover with soil. Water thoroughly and bring inside before the temperature drops below 10 degrees Celsius or the mandevilla vine will die. Provide filtered sunlight and weekly watering while the plant is indoors for the best results.
Transplant back outdoors in late spring, when the average temperate is above 10 degrees Celsius and all threat of frost has passed. If you choose to allow the vine to die back in winter, it will need to be replaced the following spring. In very warm climates, where winter temperatures don't drop below 50 degrees, mandevilla may be left outdoors all year.