"Annual vines such as morning glory, hyacinth bean, moonflower and scarlet runner bean, or perennial vines like clematis, climbing hydrangea or Boston ivy are very popular," said Greg Stack. "But tropical vines offer some spectacular and exotic flowers as well as interest that begs garden conversation.
"Many of these vines are becoming very easy to obtain at local garden centers. And, although tropical vines are not hardy in the Midwest, they can usually be easily overwintered indoors and placed back out in the spring for another season of bloom. When you save a large plant, next year's show is even more spectacular."
Here are some of Stack's recommendations to gardeners who want to try vertical gardening.
Mandevilla or Dipladenia vine produces a spectacle of flowers nonstop throughout the summer on a plant with shiny, waxy foliage. The flowers are trumpet shaped with a unique twist. Colors range from hot pink to white, yellow and reds.
Mandevilla is an aggressive-growing vine that is easily trained to a trellis or arbor and will grow 4 to 6 feet the first season. They prefer full sun and a soil that is high in organic matter and moist. Water regularly and fertilize twice a month to maintain vigorous growth.
"While these vines grow too large to overwinter as a growing plant, they can easily be stored as a dormant plant," he explained. "Leave the plant in the garden until a light frost kills back the tip. Dig up the tuberous root system and store it in a container of soil in a dark place at about 35 to 40 degrees over the winter. Next spring, replant and the flower display should be even better. This vine also makes an excellent container plant. Just move the whole container indoors for winter storage." Stack said another vine is not really a vine but more of a sprawling shrub with pliable canes that can be trained to a vertical support.
"Bougainvillea or paper flower is popular and unique because the individual small flowers are surrounded by three large petal-like papery bracts that come in almost any color you can imagine," he said. "And, because the colorful bracts remain on the plant long after the true flowers are gone, they can remain colorful for many months."
Bougainvillea prefers full sun, and because it has a very fibrous, brittle root system, it is best to leave the plant in the pot that you buy it in. Do not disturb the roots. Just sink the plant, pot and all, into another container or directly into the garden. Water as needed and fertilize once a month. Some pruning and tying may be needed to shape and control the plant.
When it comes time to overwinter the plant, lift the pot from the soil just before frost and cut it back to 6 inches. Store the pot in a cool (40 to 45 degrees) dark area until spring. In spring, bring the plant into a warm location, remove a little bit of the soil from the top of the pot and replace it with compost and water. Do not repot. Handled this way, the plants make excellent specimens in a Midwest garden.
"Passionflower vine is perhaps the ultimate image of a tropical flowering vine," said Stack. "The blossoms are a complex arrangement of floral parts that will hold any garden visitor's attention.
"Passionflower is a very vigorous growing plant and will do well in a large container or planted directly in the garden. In colder areas, it can be planted along the foundation of a house. Here the protection provided by the foundation with the addition of winter mulch allows you to leave this vine in the garden where it can act as a 'hardy perennial' vine for many years. Provide a good support or trellis for the tendrils to wrap themselves around."
Passionflower does best in a full sun location and loves the heat. If you choose to grow this vine in a container, it can easily be overwintered by allowing the plant to experience a light frost to kill back the top. Cut the vine back to 6 to 8 inches and place the pot in a cool, dark location until spring. At that time it can be placed back outdoors and watered, and growth will resume.
Clerodendrum or bleeding heart vine grows slowly enough to make it an excellent choice as a potted vine. And, because these vines get better with age, it is worthwhile to consider overwintering them. The flowers of these vines are a colorful combination of sepals and petals, often in contrasting colors. Clerodendrum do well in full sun to light shade in a well-drained soil that is high in organic matter. For best blooming, fertilize it twice a month and keep the soil evenly moist. To overwinter this vine, allow the soil to go dry, forcing them into dormancy. Store the container in a dark place at about 45 degrees over the winter.
"Vines are versatile," Stack said. "You can train them up support structures or put them in hanging containers to cascade downward. Anyway you choose to use them, these 'hot vines' will add a tropical dimension to your garden. "