Flowering Vines 101
North America is the home of horizontal gardeners. Not gardeners who work flat on their backsor spend all their time in chaise loungesbut gardeners whose vision is earthbound. A few trees and shrubs may creep into our landscapes, but our sight usually is directed down and straight ahead, making it easy for us to forget plants that grow up rather than hug the ground. Making it easy to forget flowering vines.
Gardeners in other parts of the world aren't so myopic. They use vines with abandon: to creep along the tops of walls, twine up pillars and posts, bestride gateways, blanket fences, roof arbors, and shade patios. The British, in particular, are besotted by flowering vines, so much so that any Guernsey that loiters over a patch of clover is in danger of being planted with the clematis 'Lady Betty Balfour'. Americans, always conscious of English horticultural imperialism, would do well to take this page from their garden book.
Climbers, after all, were among the first cultivated plants. Egyptian wall paintings (c. 1400 B.C.) show slaves harvesting fruit from vine-covered pergolas, and the Romans used roses, ivy, and other climbers to garland and shade. The grape was so common in ancient agriculture that it is referred to only as "the vine" in the Bible, and rare was the medieval garden whose walls weren't home to climbing plants.
Likely it was the limits of the natural worldspace, climate, water, soil, light, and competition with other plantsthat gave rise to vines in the first place. Rather than a distinct botanical category, like monocotyledons or magnolias, vines are a behavioral group, plants that adapted to their surroundings by becoming scandent. In order to move water and food easily from their roots to their leaves, they developed hollow stems.
Many true vines are tropical plants, natives of regions where the mercury stays well above 32°F. In such warm climates, the fluids moving through a vine's long, hollow stemssometimes dozens and dozens of feet longnever freeze, a process as destructive to a vine as it is to the water pipes in your home.
Some scientists believe that the climbing response of vines also is a reaction to threats. Like plants that developed thorns to protect their fruits from being eaten by animals, vines may have stretched the distance between nodes (the points on the stem where leaves form) in order to move their fruits out of the reach of predators. Or to make their flowers more accessible to the birds and insects that pollinate them.
Whatever the selective pressures, the adaptive behavior of vining species was fodder for Charles Darwin, who was always on the prowl for examples of the natural battle for survival. In 1865, Darwin published "The Movements and Habits of Climbing Plants" in the Journal of the Linnaean Society, an essay he expanded into a 200-page book two decades later. His argument was that plants evolved into climbers because of competition: "Plants become climbers, in order, as it may be presumed, to reach the light and to expose a large surface of their leaves to its action and to that of the free air."
Giving up sleep for several nights to watch a Ceropegia, Darwin recorded its attempts to find something to help it climb. Its movements, he wrote, seemed so purposeful that it appeared as if the plant could think. "It was an interesting spectacle to watch the long shoot sweeping this grand circle, night and day, in search of some object round which to twine."
The elliptical motion of twining plants, called "circumnutation" by botanists, can be clockwise or counterclockwise, depending on the species. The direction is typically at a right angle to the source of light or heat, and twining plants, if turned upside down, will uncoil and recircle their support. Guide a twiner in the "wrong" directionAmerican bittersweet, for instance, circles clockwiseand the plant will rewind itself. Similarly, a vine that is pulled away from its support will reseek it. Interestingly, the higher a twiner grows, the more tightly it clasps its support.
Up, Up, and Away
Espaliers are another group of "climbing" plantsor, more accurately, plants that have been trained to flatten themselves against walls, trellises, and other vertical surfaces. The word espalier, from the Italian spalle, or shoulder, once referred solely to the method; today the term is used to describe both the method and the plant.
Pears and apples are the quintessential plants that are pruned and trained into the set patterns of espalierpalmette verriers, vertical cordons, and more -- but the practice doesn't stop with fruit trees. Pyracanthas, forsythias, and magnolias are only three of the many ornamentals coaxed into botanical bondage, as one wag termed the practice.
Artificial but stunning, espalier transforms shrubs and trees into vinesan endorsement of the value of climbers in gardens if ever there were one.
Not all scandent plants are twiners, however. Botanists have identified more than two dozen specific ways that plants climb, but most are variations of five basic techniques.
- Vines that weave or twine, such as mandevillas
- Vines that attach with aerial roots or adhesive pads, such as climbing hydrangea
- Vines that scramble, such as potato vine
- Vines that catch with thorns, such as bougainvilleas
- Vines that clasp with tendrils or petioles, such as sweet pea
Most commonly grown vines either twine around vertical structures or adhere to vertical surfaces. The differences in how vines climb are important to gardeners because they guide us on how to guide them. For example, no golden-trumpet vine is going to climb a bare wall, as trumpet vine will. Golden-trumpet vine needs a support around which to twineand tying to get started.
One job of gardeners is to provide appropriate climbing apparatuses -- horticultural jungle gymsfor their vines. This chore also creates an opportunity to add an attractive built element to the landscape, such as a rail fence, a lamp pole, a stone wall, a graceful archway, a wrought-iron trellis, or a classic arbor. You should look for a support that meshes with the style of your house or garden, but anything can serve to support a vine. Not long ago on a trip to the Midwest to see my daughter, I came across an abandoned John Deere tractor, which had found a second career as the underpinning for a volunteer Virginia creeper. Fortunately, from my husband's point of view, the tractor was not for sale.
Keeping the Lid On
While most vines are like two-year-old childrenwho are frequently heard to announce, "I do it myself!"not every climber heads skyward at lightning speed. Some species take their time even to get started. Climbing hydrangea is a good example; as one mail-order house diplomatically phrased it, climbing hydrangea "is a bit slow to establish itself." Mine took a half-dozen years. Other vines just grow slowly, a trait that can be a virtue if you have a small garden or are cultivating climbers in containers.
Many species need a handeither a hand up or a heavy hand. Securing and guiding will help almost any climber, at least at the start of its journey, and pruning not only keeps plants in bounds but will improve their form and promote flowering. Guidelines on when to prune, which are based on when vines bloom, are covered in "Growing Vines Successfully."
But the most important key to growing vines successfully is location. Most problems can be avoided if you choose an appropriate site for the plant. That means full sun for a vine that craves it, protection from the wind for a vine that needs it, and plenty of water for a vine that demands it. A strong, vigorous plant is unlikely to become a victim of diseases or pests. Happily, most flowering vines are rarely touched by the fungal, bacterial, and viral diseases that plague other plants in the garden.
In fact, nearly all of the news about flowering vines is happy. They are an independent and wonderfully vigorous crew. The following chapters are intended to help you grow them successfully, as well as to introduce some names that may be unknown to you. Plant something new, by all means, but don't turn your back on the familiar simply because it is familiar. Some of the best known vines are also the best performers, tried-and-true plants guaranteed to do well in a variety of settings. As Connecticut garden writer Sydney Eddison observed, "The perfect plant is the one that's alive."