This twining, woody climber is grown primarily on the moist stream banks of China, Japan, and Korea, as well as south and central United States. With magnificent green leaves and beautiful flowers, the Wisteria is a favorite for bonsai enthusiasts. Keep in mind that rather than train a Wisteria to meet traditional bonsai styling, it is grown to display the gorgeous flowers.
For example, you will often see a mix of purple, white, pink, or blue flowers that appear in late spring or early summer. Following the flowering season, the Wisteria produces leaves that resemble green bean seedpods. While you can grow a number of Wisteria species for bonsai, the most favored are the Japanese Wisteria (W. floribunda) and Chinese Wisteria (W. chinensis), both spectacular species.
The goal with growing a Wisteria bonsai is to encourage flowering, which can be done through a number of techniques. However, no Wisteria will bloom until it reaches a specific age, usually around 10 years. You can use pruning of all shoots within five to six inches of the primary trunk, leaving just four to six leaves on each shoot as one option for encouraging flowers. For this, you want to perform the pruning after the flowering season, and most often about three times until fall. Then in mid-winter, you want to reduce the spurs to about four inches, just leaving three buds.
Now, after the repeated pruning, you would need to perform a hard prune in mid-winter. With this, you would gain control of the vigorous growth while still encouraging the mass production of flowers and leaves. The result of repeated pruning would be compact, dense foliage with colorful flowering, just what you want. Another technique for encouraging flowering is to repot the Wisteria immediately after the flowering season has stopped.
You will also need to provide your Wisteria bonsai with appropriate food with a low nitrogen mix. Since the Wisteria is able to take nitrogen from the atmosphere, should you provide it with food high in nitrogen, you would end up with an overgrowth of foliage while not getting the beautiful flowering. Therefore, always make sure you choose the fertilizer specific to the Wisteria shrub.
Wisteria can tolerate both partial shade and full sun. Regardless, you want to provide protection from the wind. With this being a top-heavy bonsai, winds could easily blow it over, thus causing stress. The Wisteria bonsai also needs a lot of water compared to other shrubs and trees used for bonsai. Therefore, keep the bonsai moist at all times and in the hotter summer months, place the container in a tray of water so it has a consistent supply. Just remember that you want to allow the water tray to dry out each day to avoid watering to much. Although root rot is rare with Wisteria, it can happen if the soil were to become waterlogged.
Wisteria bonsai can be trained in many different styles, as long as the flowers are allowed to cascade down. The goal with Wisteria is again to show off the flowers. Therefore, styles such as cascade, informal upright, or slanting work best. To keep your Wisteria in top form, you will need to repot it every two to three years, using basic bonsai soil. We suggest you repot in early spring to help with flowering.
If you want to propagate your Wisteria, take basal cuttings from side shoots sometime in early summer or ground layer in the fall. Finally, Wisteria is prone to Leafspot, aphids, and brown scale so watch for problems and use organic herbicides or insecticides.