Wisteria's fountains of spring blooms
Wisteria vines share Southern magnolias' stature as staples of the Southern landscape. These twining, vigorously growing plants produce compound, lacy green foliage and elongated, cascading clusters of fragrant spring blooms. Left untended, the woody vines scramble as far as 50 feet up or over whatever crosses their paths. With regular pruning, however, they transform arbors, trellises and fences into garden focal points. Does this Spark an idea?
Japanese Wisterias
Japanese wisterias (Wisteria floribunda) tolerate winter temperatures between 20 and 30 degrees below zero in U.S. Departmental of Agriculture Plant Hardiness Zone 4. These wisteria typically climb 10 to 25 feet, with a 4- to 8-foot spread. Their hanging, 1-foot to 18-inch flower clusters open simultaneously with the leaves in early or midspring. The fragrant, violet, pealike blooms unfurl from the base of the clusters down. Fall seedpods follow the blooms and often persist into winter. Numerous Japanese wisteria cultivars offer blooms in a range of colors. "Rosea" features purple-tipped, rosy-pink flowers.
Chinese Wisterias
While the vines reach similar dimensions, several characteristics distinguish Japanese from Chinese wisteria (Wisteria sinensis). Chinese wisteria has looser foliage and smaller, 6-inch to 1-foot flower clusters. Because its individual, blue-purple flowers open almost simultaneously in late spring to early summer, Chinese wisteria has a shorter, but more dramatic, bloom display. It winds around supports in a counterclockwise direction, while Japanese wisteria twines clockwise. Chinese wisteria survives winter temperatures between minus 10 and minus 20 F in USDA Zone 5. W. sinensis cultivars include white-flowered "Alba," and "Plena," with double lilac blooms.
American Wisterias
American wisteria (Wisteria frutescens) grows in USDA Plant Hardiness Zones 5 through 9, from Virginia west to Illinois and south to Florida into Texas. The 40-foot-or-more climber thrives in thickets, moist woodland and stream bank soils. Its dark green leaves emerge with 6-inch clusters of lilac flowers in early to midspring, but take longer to open completely. This American wisteria species sometimes has lighter, repeat flushes of summer bloom. Exceptionally cold- tolerant Kentucky wisteria (Wisteria macrostachya) "Blue Moon" withstands winter temperatures to Zone 3's 40 below zero. This compact vine climbs 15 to 25 feet in the south central United States' swampy soils. Its 6-inch to 1-foot clusters of fragrant blue flowers appear first in June. Like those of American wisteria, they repeat in summer.
Growing Wisteria
Wisterias grown in full sun -- a minimum of six hours of direct sunlight each day -- adapt to a range of soils. They prefer consistently moist, averagely fertile soils with mildly acidic or neutral pH. The best wisteria soils have pH readings between 6.0 and 7.0. Fertilizing the vines produces foliage at the expense of blooms. Essential care includes support sturdy enough to handle the weight of mature vines, and regular pruning to keep the plants from overwhelming their surroundings.
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