Q: I had an arbor built over my deck and would like a vine to cover it. Would wisteria be a good choice? — Patty Schroeder, Cincinnati, OH
A: For a vine over a deck, you probably want something smaller than wisteria. Most perennial vines seem slow at first, but they put on a tremendous amount of new growth every year. Wisteria, trumpet vine (Campsis), climbing hydrangea, Dutchman's pipe, variegated kiwi and even grapes are all designed by nature to scramble up large trees, so an arbor over a patio is almost nothing to them. They will require a lot of pruning. Untended for even one year, these large vines can quickly get out of hand and damage your siding, roof gutters and the trellis itself. In most cases, I think the smaller clematis and honeysuckle vines are good choices for deck arbors. I have wrestled with my share of vines over the years, and I think the best kind over a patio or deck is one that you can train mostly along the sides of the trellis, even if you don't get total coverage over the top. It is extremely difficult to properly prune a vine over a large horizontal area high overhead.
For shade overhead, a better alternative is to put lattice panels on top of your arbor's cross beams. Paint them to match the rest of the structure, then train your flowering vines to cover the sides (don't worry if some also wander up top, as they are sure to do). This approach will give you the best view of the flowers along with maximum privacy from neighbors. And the vines will be far easier to prune. Plant your vines in the ground near one of the posts for the deck. Attach some sort of mesh or lattice to the post to give the plants something to hold onto. Most vines have trouble getting a grip on anything much over an inch or two in diameter. At deck level, they will need more support to spread out along the sides. This could be lattice or horizontal wires. You’ll be rewarded with exotic flowers (and fragrance) right at eye level. If you have a very large arbor on your deck, you still might decide on one of the bigger vines trained to stay low. Send it up one of the supports and then around the top edges of the arbor — 7 or 8 feet overhead. Most of the growth will want to festoon itself down the sides as you desire. Prune out everything that scrambles over the top whenever possible (no later than fall each year). In winter ice and snow will accumulate on vines lying over the top, which in a bad year could bring the arbor down. Take the lattice panels down, too, if snow load might be a problem.