By Lindsay Bond Totten
Scripps Howard News Service
If I had the means to hire a skilled gardener, and could assign him (or her) to the tasks I didn't want to do, I'd plant wisteria. It'd be the only responsible way to own this exquisite vine, for in the crush of chores on this seven-acre farm, a wisteria vine would surely get away from me.
Other gardeners are not as cautious, for wisteria continues to be an extremely popular perennial vine. Those who can--and do--contend with its wanton ways are rewarded with pendulous clusters of fragrant lavender flowers, plus the envy of all who set eyes on them.
Most wisteria vines sold today are of the Asian variety. Chinese wisteria (Wisteria sinensis) blooms the earliest, usually before the leaves emerge. The stems of Chinese wisteria twine counterclockwise.
The racemes of Japanese wisteria (W. floribunda) are slightly larger and appear a little later in spring, with the expanding foliage. Stems twine clockwise around their supports.
Differences between the two are insignificant when it comes to pruning. Both are rampant growers that bear their flower buds on the previous season's wood. Expert advice on pruning wisterias nearly always revolves around a variation of this central theme: prune often and prune hard.
Dormant pruning in late winter relieves wisteria vines of last year's shaggy mane and reduces the stems to the bare essentials: the main trunks, each with a few side branches and two to three vegetative buds apiece.
Watch for the short, stout "spurs." These modified branches bear the flower buds, which are larger and fatter than the leaf buds and usually fuzzy, especially when they begin to swell in early spring.
Dormant pruning is followed throughout the season with routine removal of errant stems. Snip and clip. Snip and clip. Make it a point to prune long slender branches back to just two or three sets of compound leaves. Never pass the vine without pinching back a bud or two.
A benefit of frequent light pruning is to direct the vine's energy to producing flower buds for next season. The penalty for failure to prune regularly during the summer is a wisteria vine that performs poorly next spring.
Somewhat less aggressive, though still capable of toppling an arbor or trellis if left untended, is our native American wisteria (W. frutescens). While its floral display is a little less impressive than the Asian species', it's still a charming vine, displaying handsome foliage and dangling purple flowers with a sweet perfume.
With interest in native plants growing rapidly, perhaps American wisteria stands a better chance of garnering the recognition it so richly deserves. If you can't find it at your local nursery, many mail-order companies list it now.
The twining stems of American wisteria are vigorous, but less invasive and more manageable than those of the Asians. Unlike the others, our native vine blooms on the current season's growth, near the end of new branches. Because it needs time to initiate those buds, flowers appear later in the season, usually in early summer.
This trait makes pruning much simpler, because gardeners don't have to search for spur branches to protect the current crop of blooms. Dormant pruning can be heavy without sacrificing color. Frequent light pruning in summer is still recommended, however, to control strong growth and train the vine to an appropriate support.
My hopes of owning a wisteria someday are pinned on a selection of our native wisteria called "Amethyst Falls" (W. frutescens "Amethyst Falls"). Since every vertical surface here is already claimed, acquisition of "Amethyst Falls" will require either the sacrifice of an extant vine or the construction of a new support. It will be worth it.
A relatively new cultivar discovered in South Carolina, "Amethyst Falls" is a miniature version of its larger, more aggressive cousin. Within a few years, compact stems will reach just 10 to 15 feet high. Width and shape depend on training, of course, but "Amethyst Falls" will eventually climb to the top of an arbor or pergola and spread out slowly.
Most amazing about "Amethyst Falls" is that this dwarf wisteria begins blooming at a very young age. One-year-old plants started from cuttings may bloom in their nursery pots, something a standard wisteria vine would never do.
If lightly trimmed after its first flush of blooms in spring, to reduce the length of new shoots, "Amethyst Falls" will bloom again in late summer. The vines do not appear to produce seed pods--a real bonus--but if they ever did, it would be imperative to remove them to prevent seedlings from popping up like weeds. Since "Amethyst Falls" occurred as a stem mutation, seedlings would most likely revert to full-size plants.
(Lindsay Bond Totten, a horticulturist, writes about gardening for Scripps Howard News Service.)
)
