Wisteria macrostachya ‘Blue Moon’

In my neighborhood in Janesville, Wisconsin, there is a massive Japanese wisteria (Wisteria floribunda) that has engulfed a chain-link fence abutting a public park. When in bloom, it is unbelievable in color and fragrance. Upon closer inspection, its thuggish vigor is displayed by the trunks and stems embedded on the metal posts and chain-link sections and many root suckers.

I’ve seen this engulfing vigor from both Japanese and Chinese wisteria (Wisteria sinensis) in home gardens and public gardens alike and most of us are aware of the spreading nature of these species (banned and restricted in many states). Excitingly, the availability of less vigorous, native species like W. frutescens and W. macrostachya gives us an opportunity to enjoy the contributions of wisteria in the garden. My go-to wisteria is ‘Blue Moon’ Kentucky wisteria (W. macrostachya), and I’ve never regretted planting it.

The Kentucky wisteria is considered the hardiest species and listed for USDA Zones 3-9. Reaching a height of 15-25 feet (width to 8 feet or so), this woody does grow with ample vigor but I’ve not seen it become the thug that the Asian counterparts inevitably become over time. Preferring slightly acidic, fertile soil that is moist but well-drained is ideal; as is a full sun position.

‘Blue Moon’ reliably flowers in late May until early June from a young age (2-3 years) and has sporadic reblooming throughout the summer. The flowers, positioned on foot-long racemes, are quite fragrant and attract a wide range of pollinators such as bees, butterflies and hummingbirds. The pinnately divided foliage with narrow leaflets has a clean look and the late summer, seed pods mature from velvety green to brown and persist over the winter.

Adequate structural support, coupled with occasional pruning and guidance, are instrumental in keeping this vine in scale with the desired setting. Rugged arbors, staunch gateways, espalier situations and other structures that accommodate the robust twining of this native vine are a vital part of the equation for success. It is important to note that this species, despite being less aggressive than other wisterias, is not a slow-growing vine and vigilance in determining the scope and scale of its growth is still warranted and recommended. Winter pruning is recommended to establish shape and control size. This vine is both deer and rabbit resistant with very few insect or disease problems.

Mark Dwyer is currently the garden manager for the Edgerton (WI) Hospital Healing Garden after 21 years as director of horticulture at Rotary Botanical Gardens (Janesville, WI). He also operates Landscape Prescriptions by MD, a landscape design and consultation business. Contact him at mcdwyer@zoho.com.