Mandevillas are tender tropical vines that produce fragrant, trumpet-shaped flowers in shades of white, red and pink. They grow and thrive as potted plants outdoors during the growing season. Potted mandevilla vines will grow 10 feet or more in a single year. They must be stored in a frost-free area for the winter. Begin to prepare your mandevilla for overwintering when daytime temperatures drop into the 60s.
Cut back the mandevilla vines so they are about 10 inches long.
Wash your mandevilla thoroughly using a strong spray from a hose.
Water the soil thoroughly until water puddles on top of the pot. This will force out any crawling insects so you don't bring them indoors for the winter.
Spray the mandevilla vines and the surface of the soil with a horticultural oil spray to kill any remaining pests. Cover the mandevilla, pot and all, with a large plastic bag. Leave it in the bag for 2 to 3 days to eradicate any insects.
Bring mandevilla indoors when average daytime temperatures drop into the lower 60s. Remove it from the plastic bag first.
Store your mandevilla in a cool, dark unheated basement, crawl space or garage where temperatures will stay between 50 and 60 degrees Fahrenheit. Do not expose them to freezing temperatures.
Water only as needed to keep the soil from drying out completely. Do not over-water while mandevilla is in its dormant winter stage.
Move outdoors in spring after all danger of frost has past and average daytime temperatures rise to the 60s.
Re-pot mandevilla in late spring and pinch its newly growing shoots to grow a bushier, more flower-intensive vine.
Fertilize mandevilla with water soluble fertilizer when repotting and every week during the growing season. Mix fertilizer following the manufacturer's recommended rates of application. Do not apply fertilizer to dry soil; thoroughly water the mandevilla before fertilizing.