Vines are an important part of any tropical display. Many of them are fast-growing and can be grown successfully as annuals. Others should be overwintered in a sunny location in the home and moved outside in late spring.
Vines have different ways of climbing. Understanding how they hold onto and climb over structures will help you choose the right type of support. Mandevilla vines (Mandevilla) have twinning stems that wrap themselves around their structure; passionflowers (Passiflora) possess stem tendrils that hook onto and tighten around their support; while cup and saucer vines (Cobaea) have leaf petioles that wrap around their support. To care for your vines, patiently wind them around a tripod or vertical structure to achieve a fuller display and prevent them from climbing straight up to the top of the structure. Some more vigorous vines will need to be pruned or cut back to maintain their shape.
Another important consideration when deciding on trellising for vines is to understand the ultimate size, height, and spread. Some vines such as hyacinth beans (Dolichos) are vigorous growers while others such as cypress vines (Ipomoea quamoclit) are well-behaved accent points. Sometimes information on size reflects their growth habit in warmer climates so that you can expect them to vary (be smaller) in northern climes.
The black-eyed Susan vine (Thunbergia), morning glories (Ipomoea), cup and saucer vine, Spanish flag (Ipomoea lobata) and hyacinth bean are all fast-growing annuals. Start them indoors from seed 3 to 6 weeks before the last frost date. Grow in 4 inch pots with an 18 inch bamboo stake to provide initial support. Do not start them too early or you will end up with a tangled mess.
The passionflower can be brought inside over the winter and will flower if placed by a sunny window. The mandevilla vine can either be brought indoors with the passion flower or it can be cut down to its base and allowed to go dormant. If you plan to bring it indoors, It's a good idea to prune it back so that it is a comfortable size for your home. It will grow slowly during the winter months. You do not need to encourage growth at this time of year by fertilizing the plant, just water it when it begins to dry out. Sometime in February, give the plant another good pruning and begin to fertilize it once a month. Mandevilla flowers on new growth and when you place it back outside in May or June it will take off and soon be covered with flowers.
If you plan to allow your mandevilla to go dormant, keep the vine outside until it gets cool and then move it into a garage or basement that maintains a winter temperature above freezing (around 50 F is ideal). In this scenario you should cut the plant back hard, to about 12 inches. Occasionally give it water so that it doesn’t dry out, but essentially leave it alone. Bring it inside when spring is just around the corner and let it start to grow.