One of the most popular cultivars of a deciduous woody vine that has been cultivated in its native Japan for centuries, ‘Rosea’ is a real head turner because of the unusual pinkish cast of its incredibly long pendulous flower clusters. The fragrant pea-flowers open sequentially from the base of the flower cluster in late spring. The blossoms are followed by velvety green bean-like seedpods. The compound foliage is light green and lush. This vigorous twiner grows rapidly into a massive plant that can engulf pergolas and other structures.
Wisteria prefers full sun and humus-rich, well-drained soil. Soil that is too high in nitrogen may promote leafage at the expense of flowers. The beauty of these blossoms deserves to be front and center in spring so plant in high profile locations such as walkway arbors. Train youngsters to spiral up arbor posts to create a very cool look when the stem thickens with maturity. Prune side branches back to a few buds in late winter, and remove any out-of-bounds growth in summer. Beware of runners invading roofing and eaves, which can eventually cause structural damage if not promptly removed. Japanese wisteria can be trained as a small tree by staking a shoot upright, removing side shoots and restraining the top shoots by pruning for several years until the stem is self-supporting. This species is listed as an exotic invasive in several areas including the eastern United States.ding the eastern United States.
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Select a site with full sun to light shade and well-drained, deep, moist soil.
Plant in spring or fall, spacing plants 10 to 15 feet apart. Dig a hole only as deep as the root ball and 2 to 3 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.
Apply a layer of compost under the plant each spring, followed by a 2-inch layer of mulch to retain moisture and control weeds. Water plants during the summer if rainfall is less than 1 inch per week. To control growth and encourage flowering, prune wisteria after flowering in early summer by cutting side shoots that arise from main stems back to 6 inches. In fall, shorten these same laterals back to 2 to 4 buds. Remove shoots arising from the base of the plant as soon as they appear.