For those who can never get enough of wisteria's tremendous displays of fragrant spring flowers, there's good news. A new everblooming variety of American wisteria (W. frutescens). 'Amethyst Falls' begins its impressive floral show of densely clustered, 4- to 6-inch-long bluish purple flowers in spring, and continues throughout the summer in three waves of bloom. A short growth spurt follows each wave of flowers, and then the next flowering cycle begins again. The first big wave of flowers occurs in May, the second wave in mid-June, and the final burst of bloom happens in August.
This wisteria is hardy in USDA Hardiness Zones 6 through 9. It is less vigorous than other species, which is an advantage for small-space gardens. However, it still requires support in the form of a sturdy trellis or fence. It grows and flowers best when planted in well-drained soil and in full sun. Because the buds form on new growth, heavy pruning in winter is encouraged.