Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
May, 2006
Regional Report

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The native wisteria has color, fragrance, and graceful habit; what more could you ask for? (Photo courtesy of Lancaster Farms, Inc.)

Wishful for Wisteria

On a recent trip to NYC for the Cherry Blossom Festival at Brooklyn Botanic Garden, I got a heady dose of spring with all my favorite flowering trees and shrubs in full bloom: cherries, crab apples, dogwoods, lilacs, azaleas, and wisteria. I have versions of all of them in my yard, except for wisteria, and so, of course, that's the one that's tempting me. I've resisted the allure of these fragrant vines in the past because of their finicky nature and invasive tendencies. But wait ... the American wisteria -- a native -- knows its bounds, and apparently you don't have to wait half a lifetime for its bewitching blossoms. I feel a trip to the nursery coming on.

For a long time Chinese and Japanese wisteria vines have majestically draped themselves over arbors in all the finest gardens, but in recent years the native wisteria has gotten more attention, and new varieties have been developed that have more to offer a home gardener. The Asian varieties are rampant growers so they need to be pruned, pruned, pruned to keep them from getting out of hand, as well as to encourage flowers, which are borne on year-old branches. When the plant feels like it, that is. I know people who've waited years for their wisterias to bloom. "Oh, it bloomed once years ago," remarked one friend who's all but given up.

The American wisteria (Wisteria frutescens), however, starts blooming at a younger age -- even the first year of planting. It blooms on the current season's wood, so it blooms a little later than the Asians and for a longer period, typically heavily in early summer and lightly throughout the rest of the season. It's less aggressive so it requires less upkeep and is more suitable to many types of gardens. An especially lovely variety is 'Amethyst Falls', which reaches 20, maybe 30, feet and has 6-inch-long clusters of fragrant, bluish purple flowers. The first wave of flowers begins in May, followed by another wave in mid-June and another in August.

Growing Tips
Wisterias prefer full sun or partial shade and well-drained, deep, moist soil. Dig a hole only as deep as the rootball and two to three times as wide. If your soil is in very poor condition, amend the soil you've removed from the hole with a small amount of compost. Otherwise don't amend it at all. Carefully remove the plant from the container and set it in the hole. Fill the hole half full with soil, then water it well to settle the soil and eliminate air pockets. Let the water drain, then fill the remainder of hole with soil, and water thoroughly. Spread a layer of compost under the plant each year and top with mulch to retain moisture.

Though less weighty than its Asian cousins, the native variety does need a sturdy support system that will stay in place year after year. I'll be planting mine to climb a wooden arbor over a deck, but I've also seen the vine supported by heavy-duty wires strung diagonally across a corner of a terrace (where an ell meets the main part of the house) and attached to the side of the house at both ends.

American wisteria is rated hardy to zone 5, and you can give it an edge by planting it in the warmest microclimate in your landscape, such as an arbor adjacent to your house or another building. Provide the base of the plant with some winter protection.

Pruning for Flowers
Since you want to encourage lots of new growth that will produce the flowers, prune back American wisteria in late winter, leaving four buds on each stem of last year's growth. After each flush of blooms, lightly trim the stems, and prune lightly as needed throughout the summer to train the vine to your trellis or arbor.

Even when not in bloom, the vine's leaves and tendrils create a lacy canopy so give it a place of prominence.

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