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Flowering vines are such a versatile and functional garden element. American wisteria performs the role with artistry and efficiency, whether trained over an arbor or trellis or allowed to meander up the side of a wall. This wonderful vine brings an abundance of beauty to the garden.
This wisteria is a great choice if you want to add a striking vertical element to the garden that brings bumblebees zooming to your yard from all over. Its easygoing nature and robust growth habit make this wisteria a popular one, and it’s a native alternative to its more aggressive Asian cousin.
Plant Overview
| Plant Type Deciduous Perennial Vine Family Fabaceae Genus Wisteria Species Frutescens | Native Area Eastern and Central United States Exposure Full sun to partial shade Height 15’-30’ Watering Requirements Moderate | Pests and Diseases Aphid, wisteria scale, longhorn borer, honey fungus, Phytophthora root rot, mosaic virus, canker Maintenance Moderate Soil Type Moist, well-drained, fertile Soil pH Acidic 6.0 |
What is American Wisteria?
When many gardeners hear the word wisteria, they get a little bit nervous, as some prevalent species, Chinese Wisteria and Japanese Wisteria, are invasive in a significant portion of North America. These plants were once beloved for their stunning floral display but easily get out of hand and choke out much of the native plant life in an area.
American wisteria looks an awful lot like the invasive type but without the danger of creating a monoculture or overwhelming other plants in your yard. This wonderful climbing vine brings a whimsical atmosphere to the garden with its prolific panicles of fragrant flowers.
History
These woody, climbing vines were first named by the English botanist Thomas Nuttall in honor of American anatomist Caspar Wistar. Not to be confused with the Chinese and Japanese plant species, which were brought to the United States in the early 1800s, this wisteria is a US-native plant and not invasive like its Asian counterparts.
Native Area
The species, Wisteria frutescens, is native to forests in the Southeastern United States and mostly grows wild in wet areas of the forest and along stream banks. The range of this original species stretches from Virginia to Texas and South to Florida. It also extends north to Michigan and New York State.
A separate species, Wisteria macrostachya is commonly called Kentucky Wisteria. It has been classified as its own species at this time but is very similar and also native to the United States, so caring for this plant follows the same guidelines as W. frutescens.
Characteristics
Wisteria is a perennial, deciduous, climbing woody vine that reaches up to 30 feet tall at maturity. The strong vines need support and will twine vigorously along whatever support is offered.
The oblong leaflets are deep green and have a glossy finish. The foliage changes to a vibrant golden-yellow color in fall, adding to the charm of this sturdy vine.The flower clusters are smaller than Chinese or Japanese species and only bloom on new wood, so pruning increases blooming.
The blooms are a beautiful shade of bluish-violet, appearing in draping clusters from June through August. A vine takes about five years to mature and will not flower until this point, so growing a plant from seed can result in a very long wait for flowering.
Individual flowers are about one inch long, two-lipped, and quite fragrant. The Kentucky species smells like grapes, while the common species has a more floral scent. The racemes upon which the flowers bloom are about six inches long.
American wisteria is cold-tolerant and grows best in Zones 5-9. This is a fast-growing plant that can gain up to 10 feet in length per year until it reaches maturity. If you need to contain your wisteria, be vigilant about pruning, as this vine is strong and can overtake other, weaker plants.
After the flowers fall, seed pods develop in their place. The smooth pods contain seeds which are considered toxic to humans and pets. The toxic compound contained in the plant is called Wisterin. It occurs mainly in the roots, stems, bark, and seeds. If ingested, it can cause severe gastrointestinal discomfort.
Uses
While most parts of the plant contain a toxic saponin, the flowers are free of this compound and are edible. They are commonly used to prepare tea.
American wisteria is predominantly grown as an ornamental plant. Its climbing habit makes it ideal for covering unsightly landscaping or architectural elements in a short period of time. Pollinators are very attracted to Wisteria flowers, especially bumble bees.
Where to Buy
Both seeds and starts are widely available online. Nurseries commonly carry the plant as well. Make sure to identify the wisteria that you purchase, and buy the American type rather than an invasive species.
Planting
Plant between October and April. It is best to choose a location that is not very close to the home, as it can grow quite heavy and will climb any structure within reach. Choose a space that gets a lot of sun exposure and allows for support, such as a trellis or arbor to be installed.
If planting from seed, sow the seeds indoors and transplant in spring when the ground thaws or temperature warms up in warmer climates that do not experience a hard freeze. If you’re transplanting, wait for this time, and dig a hole that is as deep and twice as wide as the root ball, spacing individual plants at least 10-15 feet from each other.
How to Grow
Wisteria is known for being a low-maintenance plant. The vines do not require much attention for most of the year, and the plant is drought-resistant once established but prefers to be planted in moist soil. If you desire a more organized appearance, this wisteria takes well to pruning and shaping and can be trained into a pleasing form.
Light
Full sun is required if you want to see this plant flower to its best potential. While it can survive in partial shade, it won’t produce nearly as many flowers, and the foliage may become more sparse and leggy.
If planted in too much shade, your vine will survive, but it won’t flower. It is difficult to give this plant too much sun, but in colder climates, give it some protection from cold winds.
Water
This plant naturally grows in moist areas such as swamps and riverbanks, so it can handle, and rather prefers, to be planted in an area that stays moist, like a rain garden. In its first year, it is important to keep your wisteria watered, giving it at least an inch of water per week. In hot weather, water more regularly.
Once it is established, you don’t need to water regularly as long as there is adequate rainfall. During times of extended drought and in the hotter months, supplemental water keeps your vine happy.
Soil
Soil type is not ultimately important to wisteria vines. However, they do need soil that retains moisture but is well-draining. Acidity is another important factor in soil condition, as too little acidity deprives wisteria of nutrients and results in chlorotic foliage. Chlorosis takes the form of faded and yellowing leaves.
Temperature and Humidity
Growth is best in temperate climates, but it is cold hardy to -20°F (-29°C), so it can be grown further north. It’s just not likely to grow as vigorously. Some species survive temperatures as low as -40°F (-40°C)!
In terms of humidity, higher levels are not imperative, nor are they harmful. The plant grows naturally in a wide range of climates. Some of those climates are very humid, and others are less so. It doesn’t thrive in ultra-humid tropical climates like South Florida, but it is a moisture-loving plant that doesn’t mind moisture in any form.
Fertilizing
Wisteria is part of the legume family, and as such, it is a nitrogen-fixing plant. For this reason, you really won’t need to fertilize often. The plant draws in atmospheric nitrogen and pulls it down to the roots for its own use and that of neighboring plants, as well.
In spring, a single application of a high-phosphorus fertilizer will boost your plant’s blooming ability. Phosphorus is the second number in the fertilizer formula and assists in cell development and protection. The bloom time for a healthy plant can span through spring and into the summer.
Maintenance
Wisteria survives with very little maintenance from the grower, but there are some things you can do to create a more pleasing growth habit and shape, as well as increase blooms and prevent the plant from re-seeding itself.
Because the plant blooms on new wood, and pruning promotes new growth, pruning inevitably results in more flowers. Pruning should take place twice a year, with the initial prune in early spring before the leaves emerge.
Perform the second major pruning after the blooming period ends to control the growth and size of the plant. You can prune your vine’s branches back to six inches, which will thicken the stems and result in more branching. As a result, more flowers bloom the next season.
Growing in Containers
You can grow wisteria in containers, but they require a lot more maintenance this way. Choose a smaller pot initially to restrict the growth of roots. Repot in a large container when the plant achieves the desired size and expect to fertilize it more regularly.
Propagation
You can grow wisteria from seed, but it takes much longer for the plant to mature this way. You could end up waiting up to five years before you get any flowers from your young plant. The most effective way to propagate this plant is using cuttings.
The ideal time to propagate your wisteria is when you prune it, as you already have plenty of cuttings to choose from.
- Use a clean, sharp hand trimmer to remove a softwood cutting about six inches long. Your cutting should be soft, new growth, with healthy-looking leaves.
- Remove the leaves from the lower portion of the cutting and dip the cut end in rooting hormone before planting it in a moist potting mix.
- Create a makeshift greenhouse to hold in moisture using a plastic bag. Create a tent over the top of the container.
- Place your cutting in a bright spot and keep the soil moist. Roots should take about a month to form at which time the young plant can be transitioned outdoors to be planted in the ground.
Common Problems
Lack of Flowers
Most often, a lack of blooms or a poor flowering season is the result of too little sunlight. The more sun your wisteria gets, the more flowers it produces, and likewise, in more shade, it blooms less.
Pests
Beetles, aphids, and leaf miners can all be an issue. All are easy to identify by the type of damage they cause or their physical appearance. Leaf miners can be difficult to see, but the damage they cause is not. Snaking patterns on the leaves that cause the leaves to shrivel indicate the presence of these pests.Remove these as they appear.
Blast your plant with water to remove aphid infestations. Japanese beetles can be hand-picked and given to birds to eat, or drowned in soapy water. Long horned borers sometimes make their homes in old wood. Remove this at the end of the season to prevent them.
Neem oil is an effective treatment for aphid and scale pests. If this fails to do away with the harmful insects, an application of insecticidal soap should be effective. It is best to use these products when flowers are absent to avoid killing beneficial insects.
Diseases
The two prevailing diseases that affect American wisteria are the root diseases honey fungus and Phytophthora root rot. Both of these fungal diseases are caused by waterlogging. Planting your wisteria in soil that drains well is the best protection against these fungal diseases.
Powdery mildew can be an issue for wisteria wines that are dense and live in very humid climates. If you have a lot of humidity to contend with, you may find that you need to thin out the plant to increase airflow, which cuts down on this issue drastically. Remove any damaged leaves as you notice them.
Mosaic virus and canker are two diseases without any cure. If you notice ringed lesions on the leaves of your wisteria or oozing wounds in the growth nodes of your vines, it’s one of these two, respectively.
You can prevent infections of healthy vines by planting them in conditions that suit their needs. Avoid planting in areas and near plants with these diseases, and wait for at least two seasons before planting in previously affected areas.
Frequently Asked Questions
How Long Does American Wisteria Bloom?
Wisteria can bloom for several months, depending on the conditions. Keep your plant watered and apply fertilizer in the spring for the most robust flowering season which lasts from mid-spring and through much of the summer.
Are All Wisteria Flowers Purple?
No, ‘Nivea’ is a variety that produces racemes of creamy white flowers. ‘Blue Amethyst’ produces blooms that are more blue than purple.
Is wisteria safe for dogs?
The flowers are not toxic, and small amounts of leaves are not likely to cause harm. However, ingesting the seeds or wood of the plant will cause stomach upset, sometimes severe.
Final Thoughts
American wisteria is a striking and sturdy plant that makes a major garden statement. Planting this wonderful vine will draw plenty of pollinators, and human visitors will enjoy the beautiful flowers and their sweet fragrance. With just the occasional pruning and a little bit of attention to soil moisture, your wisteria vine will take off and cover that arbor, fence, or trellis in no time at all.
