My small back yard garden has a definite Asian flavor including asymmetrical beds complete with water fountains and trees, birdbaths, temples, winding gravel walkways and plenty of flowers.
I think of it as a romantic interlude, a quiet place to dream and be grateful for nature’s beauty. In my mind, all that was missing from this lovely respite was wisteria. Nothing rivals the beauty of a wisteria in full bloom with its large fragrant flowers. So, last fall, I decided to add a wisteria arbor to my landscape.
According to the Ohio State University Extension Fact Sheet “Growing Wisteria” (ohioline.osu.edu/hyg-fact/1000/1246.html), wisteria are vigorous twining vines with wide landscape usage where space permits and gardeners commit to keeping them in bounds. Among their attributes are hardiness, vigor, longevity and the ability to climb high. Two species of wisteria are typically grown in home gardens: Chinese wisteria and Japanese wisteria. Japanese wisteria is known for its fragrant violet blossoms borne in 8– to 20-inch clusters while Chinese wisteria clusters are slightly larger. Chinese wisteria is not quite as hardy as the Japanese and also not as fragrant.
My first challenge in adding wisteria to my garden was locating it in a sunny area where the plant would have room to grow. Wisteria requires six or more hours of direct sun per day and a deep, moderately fertile, moist soil. Although they will adapt to most soils, a slightly acid soil pH of 6.0 to 7.0 yields best results. Because my garden is small I had to make a small compromise (this may later prove to haunt me) by locating the arbor within a foot of a mature Bradford pear tree. I added a gravel walkway underneath and relocated several day lilies to make room.
I know that good site preparation will help ensure plant establishment. I prepared the soil in an area two to three feet in diameter and 18 to 24 inches deep. I mixed peat moss and compost to improve soil aeration and drainage. I purchased at end of season an inexpensive sturdy metal trellis and secured it in the ground, as wisteria climbs best on wires, trellises, arbors and pergolas. I placed the root ball of the plant in the hole at the same depth as it grew in the nursery and filled in the hole with the soil mix tapped firmly around the root ball.
Also important to successfully growing Wisteria is watering, feeding and pruning. It does not like to be dry. It is particularly important to water when the flower buds for next year’s bloom are being set usually August through September. Wisteria does not need much nitrogen at all since it is a legume and capable of fixing its own nitrogen. However, if a soil test determines inadequate levels of potassium, apply superphosphate (at the rate of two ounces per square yard and potassium sulphate (one ounce per square yard) in the spring. Wisteria should be pruned but sources vary on when. One source said late spring or early summer; another said late August and early spring.
Like most gardeners, I was drawn to wisteria for its blossoms so you can imagine my disappointment this spring when it failed to bloom. I later learned that producing only vegetation is one of the plant’s notorious tendencies. I heard of one case where the wisteria plant failed to bloom four years in a row. The owner adopted a puppy who promptly chewed the wisteria to the ground. The following year, the wisteria was wild with blossoms. I think the lesson to be learned is that wisteria love to be pruned.
Age of the vine is a major factor determining whether a Wisteria will flower or not. Vines grown from seed may need 10 to 15 or more years in order to produce flowers. Vines grown from cuttings or grafted plants typically flower sooner. Also, in severe winters, flower buds may be injured or killed. Successful wisteria gardeners often recommend root pruning, applying superphosphate, rigorous pruning for the shoots and planting in full sun. As for me, I think I will just get a puppy.
Michele Pearson is an OSU Extension Master Gardener volunteer.