Written by s • American Wisteria

With the first hints of spring already arriving in the warmer states, before long the wisteria will be in bloom. These plants must surely be among the most spectacular of all climbing plants, and a well-grown plant simply takes your breath away. Blue is always admired in the garden, perhaps because of its relative scarcity, but also because it looks like fragments of the sky have fallen to earth and lodged in the trees. There are several features that make Wisteria so special, starting with the fact that the clusters of blooms are often so large, being typically 12 inches long, and sometimes even longer. Secondly, they bloom on bare branches, so there are no leaves to obscure the flowering, or diminish in any way the intensity of its color. Finally, when look closely at, the flowers have parts in at least two shades of blue, so when combined together the coloring is richer than would be possible if they were just a single color.

Problems with the Chinese Wisteria

However, for all its beauty, Wisteria is not always welcome. Like inviting an elephant to your party, it can just take up too much room. Left untrimmed it will quickly grow 60 to 80 feet tall, smothering arbors, trellis, trees and even houses in twining branches that seem to grow faster than can be possible. This is great if you have a lot of space, but otherwise it often creates a problem, so it is no wonder that some gardeners are only half-hearted in their welcome for such a beautiful plant. Also, if you garden in cooler areas you will have no problem growing a large plant with leaves, but the flowers are quite sensitive to cold, and so they are rarely seen in the North.

Strangely, although there are only a handful of species in the genus Wisteria, it is the Chinese wisteria that is usually grown. Why is this strange? Because North America has its very own native Wisteria, which is not only smaller and more manageable, but is adapted to colder conditions, and flowers well where the Chinese plant does not. Perhaps it was the enthusiasm for all things Chinese that happened in gardening around the beginning of the last century, but for whatever reason, America’s own Wisteria is, as the saying goes, “a stranger in its own land”

The American Wisteria

In forests and along the banks of streams, over an area stretching from New York State, to Iowa, and through Virginia south into Florida and Texas, can be found the American Wisteria. This plant, Wisteria frutescens, twins up into trees to the relatively modest height of only 25 feet, making it a lot more manageable in gardens than its Chinese cousin. It has the same hanging clusters of rich blue flowers. On the negative side, the flowers clusters can be small, only six inches long in some varieties, but this makes them more charming, and certainly more suitable for smaller gardens. Clever bonsai growers even train this plant into dwarf specimens, where the smaller flower clusters are more in scale, creating a stunning miniature scene. That said, this plant makes up in abundance what it lacks in size, since while Chinese wisteria flowers just once, the American plant blooms through summer and often in fall too, meaning you are rarely without some flower clusters glowing in your garden.

There are two main forms of this plant grown in gardens, and each have their own special properties and charms.

Amethyst Falls Wisteria

The Amethyst Falls variety lives up to its name, with stunning lavender-blue flowers spread across the bare branches in spring. The flowers expand into hanging clusters at least six inches long, with a soft, elusive fragrance. Not content with a single display in spring on its bare branches, this plant returns in summer with more blooms, this time nestled among the large, ferny leaves. Since it grows no more than 25 feet tall, it can easily fit onto a fence or arbor, or climb into a large tree. It will not engulf all in its path, as can happen with the common Chinese wisteria.

Blue Moon Wisteria

If you want larger clusters of bloom, then the Blue Moon Wisteria variety should be your choice. The blooms hang down in large clusters that reach 12 inches or more, and the individual flowers are purple-blue – a stunning effect. It also has a stronger fragrance, and is very close in overall appearance to Chinese wisteria, without its rampant ways. Although sometimes considered a separate species – Wisteria macrostachya – it is much more likely to be simply a variety of Wisteria frutescens. Often called the Kentucky Wisteria, this plant is outstanding for its hardiness. Reliable to minus 40, it will bloom in colder areas where Chinese wisteria never will. This brings wisteria within the reach of almost everyone, so northern gardeners no longer need to look in envy at those southern arbors dripping in blue.

Growing the American Wisteria

This wisteria will grow in any garden soil, and all it asks for is a sunny spot – to give the most blooms – and a reasonable supply of water. Good pruning habits are the key to success with wisteria. With pruning it can even be grown into a free-standing plant, but it is easier to grow it on a sturdy frame, against a wall or covering an arbor. Pruning is done twice a year. In early spring, just as the buds begin to swell, younger branches should be cut back to the fattest buds, which form at the base of the stems. These are the flowering buds, and after this spring pruning there will be nothing to obscure their splendor. The second pruning should be in summer, and can be done as needed. New shoots that are not being left to enlarge the plant are cut back to about 6 inches long, just above a leaf. This encourages the development of those basal flower buds and ensures a profuse display of blooms.

 

The American Wisteria deserves a lot more attention. In smaller gardens, and in colder ones too, it allows gardeners to grow this wonderful vine without bringing a monster into your home. If patriotism is not enough, then a love of beauty, color and form should surely be sufficient to cause renewed interest in this beautiful plant.