Does Wisteria Grow In Washington State

Wisteria is a historic genus of the Leguminosae family of peas that dates back to the Miocene Era (7 to 26 million years ago). While two wisteria species have their roots in eastern North America, the majority of wisteria species are native to eastern Asia. In 1862, a Japanese species was brought to the United States. Wisteria floribunda, which is known as the wisteria in our yard, was presumably developed from seed and was planted here more than a century later. The botanical name of the genus is Wisteria, and the Japanese name is Fuji, or Noda Fuji. It was named in honor of Dr. Caspar Wistar (1761–1818), a professor of anatomy at the University of Pennsylvania. In earlier sources, the name has also been spelt Wistaria.

Japanese and Chinese wisteria, two Asian species, gained the most popularity in the West thanks to their prolific bloom, enormous flower clusters, and the consistent smell and colors present in the cultivated forms (cultivars). Japanese wisteria, in Peter Valder’s opinion, is the more ornamental plant (Wisterias: A Comprehensive Guide, 1995):

“It blooms for a longer period of time, has a more graceful growth habit, more attractive blossom and leaf disposition, and more effective fall color thanks to its multi-flowered racemes.

Native to Japan, wisteria floribunda can be found in the Honshu, Shikoku, and Kyushu mountains and hills. It has been grown for more than 1200 years in Japan, both inside and on the outskirts of woodlands, in locations with light shade. Individual plants can live for 100 years or longer. It was referenced and lauded for its beauty in early Japanese literature, starting with the Kojiki (also known as Records of Ancient Matters), which was compiled in 712 from oral traditions. It was once solely known to the nobles due to the purple hue of the blossoms, particularly the illustrious Fujiwara clan of the Heian dynasty (7941192).

Japanese wisteria was originally only linked with the nobles, but over time it was associated with all social strata. It was long-lived, symbolized fertility, love, and longevity; as a result, it became a favored ornamental theme, appearing in poetry, art, and other facets of Japanese culture. Many wisteria viewing spots had been formed by the Edo period (1603-1868), notably in the areas close to Kyoto and Edo (now Tokyo). The custom of admiring wisteria is still practiced today. It is a type of hanami, which is the practice of seeing cherry blossoms (flower viewing). The Ashikaga Flower Park, Kawachi Fuji Garden, and Kameido Tenjin Shrine are all well-known locations.

In contrast to Chinese wisteria, which climbs counterclockwise, wisteria floribunda is a vigorously growing deciduous woody vine. It will eventually grow strong enough to reach the tops of trees with its twining branches. Over time, the plant’s trunk thickens and becomes incredibly heavy, inflicting harm to the plant or building that it is supported by. Wisteria should be trained on a strong pergola or arbor that can sustain its weight to avoid this. This medical procedure did not become widespread in Japan until the late 17th century.

Japanese wisteria thrives in full sun and moist, deep, fertile soils with varying pH levels. It is hardy to USDA Zone 5 (minimum temperature -20 to -10 degrees F). Although there is a great deal of variation among plants living in the wild, the following traits are typical. When mature, the compound leaf turns a brighter mid-green from its juvenile pale green or bronze-green color. On the stem, the silky leaves develop in an alternating pattern. Each compound leaf has 13–19 leaflets. With age, the slick gray bark takes on a beautiful appearance. Old trunks are frequently said to as “muscular and fluted. The colorful flower racemes, which come in various violet tones, can be anywhere from 8 to 20 inches long and sometimes even longer. From the raceme’s base to its pendulous peak, each blooms open one at a time. Although 120 volatile components were successfully isolated from flowers in 1988 by scientists, scent in seedling plants varies. Autumn brings out the yellow hues in the leaves. Pendulous, velvety fruits “about 4-6 inch long pea-pods. In October, they take on a brownish hue and last through the winter. In Japan, named cultivars have been well-known for many years, and new ones are constantly being introduced. A well-established cultivar of W. floribunda called “Macrobotrys” has racemes that are extraordinarily long and fragrant blooms (2 to 4 feet).

Seedling wisterias differ from cultivars not just in terms of scent, flower color, and raceme length, but also in how long it takes for plants to start blooming. Different cultivars can flower at a young age; however, seedling plants typically need 10 to 15 years to begin blooming. Because of this, gardeners looking to buy wisteria are recommended to go with a cultivar rather than an unidentified seedling plant. Wisteria should be planted in full sun, well-drained soil, and fertilized with a low-nitrogen, high-phosphorous, and high-potassium fertilizer to promote blooming. An established plant can benefit from root trimming, which involves severing the roots in a circle approximately 18 inches from the trunk using a spade.

Wisteria should be clipped at least three times a year because it is such a robust plant. According to Peter Valder, Japanese wisteria needs more meticulous trimming than the Chinese variety:

“With this plant, it appears that any significant thinning and reshaping should be done at the end of flowering, and that all new shoots are then cut back to two or three leaves rather than being entirely destroyed. This often entails a significant pruning in the late spring after the first new growths have emerged, a second, considerably less strenuous pruning around six weeks later, followed by a tidying up of the few long shoots generated afterwards so that the plants look neat for the autumn. When their leaves start to change and the pods dangle gently below, they become especially beautiful. By that time, they ought to have a sturdy foundation and a lot of short lateral stems with dormant flower buds.

Similar to Laburnum, a different vine belonging to the pea family, Wisteria produces deadly seeds, especially for kids and animals. It is unknown whether the concentration of the poisonous saponin wisterin in other plant sections is high enough to result in harm or death. Surprisingly, traditional Chinese medicine used wisteria plant parts and seeds for both eating and medicinal purposes. These were not customary Japanese habits.

The strong shoots of Japanese wisteria were employed to make the ropes used in home construction before carpentry tools were created. Cloth was made by weaving the bark. To this day, flowering stems are still trimmed for ikebana, the traditional Japanese art of flower arranging. The bulky vines are cultivated on pergolas, sculpted to resemble trees (henceforth referred to as standards), and used in bonsai. In some parts of Japan, you can still find old houses surrounded by wisteria bushes that resemble swimming dragons.

Will wisteria grow in the Pacific Northwest?

Wisteria may get fairly heavy and needs solid supports, therefore when it is planted, care should be made to ensure a suitable structure is being used, such as a sturdy arbor, pergola, or fence.

The young vine needs to be wound or tied to the vertical structure in order to provide Wisteria with some guidance. You can do this by carefully looping the young shoot around the arbor, pergola, or fence’s wooden pillar. Due to the fact that this trunk will enlarge with time, you don’t want to clamp it particularly tightly to the wood. As an alternative, you can teach the branches to grow vertically by attaching a string from the plant’s base to the top of your building. Wisteria is content to scramble across a horizontal surface, so after the vine has established itself on the top half of your building, you can remove it.

Many pieces of gardening literature make the assertion that American hybrid plants are less hardy or less likely to bloom repeatedly. Less tenacious is a pretty relative term, though. We are still dealing with wisteria, which may grow five to ten feet in a single season in robust specimens. Regarding flowering, you will often get a large rush of spring blooms and frequently another flush later in the summer under perfect growing conditions and with the right species for your climate (usually at about thirty percent of the volume of the spring bloom).

Here in the Pacific Northwest, a well-established wisteria should be in its bloom cycle in April or May, with Chinese cultivars blooming before leaf-out and American and Japanese cultivars blooming after leaf-out and just before Chinese cultivars. Sometimes during the growing seasons, very well-kept wisterias will blossom, although never to the extent seen in spring.

Some of you might be shaking your heads and saying, “My plant has never even blossomed once!” This is undoubtedly conceivable and might be connected to one of the following problems:

High-nitrogen fertilizers: If your plant is near a fertilized lawn or if you use one, you will be encouraging a lot of vegetative development at the expense of flowering (nitrogen, phosphorous, and potassium (N-P-K) strength is given numerically on packages, with nitrogen being the first number). Since wisteria belongs to the family of legumes and peas, it may have some nitrogen-fixing abilities, which would increase the fertilizer factor.

Light: Wisteria can thrive in areas with partial shade, but it needs at least six hours of direct sunlight for flowering.

Frost: Just like many spring-flowering plants, flowers or their buds can be harmed or even killed by a cold snap.

Disease and pests: This is quite unusual. Wisteria scale is the largest pest, but it’s not a huge issue in the Pacific Northwest. Wisteria scale has only ever been reported to Swansons once, in my experience. Given the size of wisteria plants and the density of the foliage, systemic insecticides are preferable to foliar treatments for treatment. If wisteria is planted very incorrectly or is cultivated in an area that is overly damp with inadequate drainage, it may occasionally have root rot or graft failure.

Water: Wisteria prefers soils that are fertile, moist, and well-drained. As a result, irrigation to a certain extent can be beneficial, especially if the plant is in a location that is particularly dry given our drier Mediterranean summers.

Wisterias are known for tolerating all types of aggressive pruning, however pruning that is done improperly or at the wrong time will significantly reduce flowering.

Maturity: When a plant is ready to flower, it is referred to as being “adult.” For certain plants, this process can take just one season or years. From seed, wisteria might take 20 years to bloom. Fortunately, this doesn’t happen very often in the nursery industry. The plants we observe, especially the hybrids and cultivars, are grafted or cultivated from rooted cuttings and begin to bloom at a young age—roughly 7 years.

Don’t worry too much if you planted wisteria this year (or perhaps a few years ago) and it didn’t bloom. It may take some time for wisteria to establish itself and begin producing its stunning flower show on a regular basis. Up to 7 years may pass before very young plants begin to blossom freely. However, I have read reports of plants blooming in their first year after planting. Fortunately, producers usually make the plants available to us when they are 4–8 years old, so once planted properly, you won’t have to wait very long for blossoms.

However, there are a few things you may do to encourage flowering the following year if you have an older plant that either won’t flower or does so intermittently (i.e., once every few years).

I’ll start with the fundamentals: root pruning and nutrients. The second article in this series will discuss pruning, which is by far the best strategy for encouraging re-blooming.

Where can wisteria be found?

It is well known that wisteria take a very long time to bloom. For two to three years after planting, don’t anticipate blossoms. Some readers swear by the following technique to encourage blooming:

  • To cut into part of the roots, take a shovel and drive it 8 to 10 inches into the ground approximately a foot and a half away from the main trunk of the wisteria.
  • Approximately half of the roots should be damaged for the shrub to be shocked into reproduction (flowering).
  • Don’t worry—impossible it’s to harm this unchecked, unwieldy, frequently invasive shrub!
  • The flowers of wisteria can also be impacted by chilly winter temperatures.

Native Wisteria

Consider growing a wisteria species that is indigenous to North America if you live there, such as:

  • Wisteria frutescens, also known as American wisteria, thrives in zones 5 through 9. Its original states span from Virginia to Texas, the southeast to Florida, and up into New York, Iowa, and Michigan in the north. The vine is 25 to 30 feet long, has glossy, dark-green leaves, and after the plant has begun to leaf out, develops huge, drooping clusters of lilac or purple-blue flowers. Only new wood will display the blossoms. Notably, the blossoms are typically less aromatic than those of Asian wisterias.
  • In zones 4 to 9, Kentucky wisteria (Wisteria macrostachya) flourishes. Similar to American wisteria, this late-bloomer is a native of the Southeast of the United States (it is sometimes considered a variety or subspecies of American wisteria). The Kentucky wisteria is the quickest to blossom, bearing faintly fragrant bluish-purple flowers after only two to three years of growth.
  • A gorgeous, silvery-blue cultivar of the native Kentucky wisteria called “Blue Moon” is particularly hardy. In late spring or early summer, it blooms. It can go as chilly as -40F. (-40C).

Non-Native Wisteria

  • Despite the fact that they are frequently marketed at nurseries and garden centers, Chinese wisteria (Wisteria sinensis) and Japanese wisteria (Wisteria floribunda) are non-native, invasive species, hence we do not suggest them for North American gardens. They can reach lengths of 30 to 60 feet and are hardy in Zones 5 to 9. (and beyond in the Southern U.S.). Japanese wisteria comes in two popular kinds, including:
  • Popular plant known as “Honbeni” displays clusters of pink flowers in the late spring.
  • “Alba” (also known as “Shiro Noda”) yields beautiful clusters of snow-white flowers in the late spring.

Are Wisteria Toxic to Pets and Humans?

Yes, the wisteria plant contains lectin and wisterin, which are poisonous to people, animals, and even pets. If taken in significant quantities, these poisons can result in anything from nausea and diarrhea to death.

If pets or young children frequent the area, it is a good idea to remove the seedpods after the plant has flowered because the material is particularly concentrated in the seeds and seedpods. Unaware children or animals won’t think twice about eating as many seedpods as they can because they are not unpleasant to taste or have an instant effect. In case of ingestion, contact your neighborhood poison control center.

Wisteria will it withstand the winter?

Don’t panic if your wisteria begins to drop its leaves in the fall. Deciduous wisteria predominates. Winter doesn’t keep it green, but the leaves will come back in the spring.

Before dropping their leaves, some wisteria varieties put on a show of fall color as the leaves turn yellow or gold. If it’s happening in the fall, there’s typically nothing to worry about unless you’re also observing other symptoms like an insect infestation. Yellowing and dropping leaves can be signals of disease and other problems.

While Evergreen Wisteria (Millettia reticulata) is more challenging to grow, all true Wisteria are deciduous. Your Evergreen Wisteria will most likely maintain its leaves throughout the year if you have hot summers and brief, mild winters with little below freezing. This is zone 9b and higher in the US, which includes a portion of California and Arizona as well as the southern half of Florida and Texas.

Evergreen Wisteria is deciduous like regular Wisteria in more temperate regions, so you may anticipate it to go dormant for the winter and sprout new leaves in the spring. You probably won’t be able to cultivate Evergreen Wisteria in a location that is colder than USDA zone 8 because even deciduous habit cannot shield it from prolonged, bitterly cold winters.