How to Grow American Wisteria

American Wisteria (Wisteria frutescens)

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Wisteria is known for its enchanting cascades of purple-blue blooms. Chinese wisteria is often seen sprawling over archways or pergolas, but this variety can be invasive and aggressive. However, there is another non-invasive and less aggressive variety: American wisteria.

Native to North America, this variety (Wisteria frutescens) can still reach up to 30 feet in height and width, showering any nearby structure in clusters of mesmerizing blue flowers. However, you may have to wait five or six years for the vine to mature and produce flowers. It has pinnate, shiny, dark leaves and pea-like flowers that hang in clusters about 5 to 6 inches long. After flowering, American wisteria creates smooth, bean-like seed pods.

With a more controlled manner of growing, American wisteria offers the perfect solution for many who long for this plant's stunning flowers in their own garden.   

Botanical Name Wisteria frutescens
Common Name American wisteria
Plant Type Vine
Mature Size 20 to 30 ft. long
Sun Exposure Full, partial
Soil Type Moist but well-drained
Soil pH Acidic, neutral
Bloom Time Spring, summer
Flower Color Blue, purple, white
Hardiness Zones 5 to 9, USA
Native Area North America
Toxicity Toxic to humans and pets

American Wisteria Care

The beauty of this vine is in its abundant foliage and rapid growth. However, since it can grow to huge proportions, a strong structure is needed to offer support. Archways, arbors, fences, or trellises make perfect options. Although it may be tempting to let the vine crawl up the side of your home, it can become very heavy and eventually cause damage.

While not considered invasive, this plant's fast-growing nature means it may be better if grown in an isolated area. Otherwise, it may choke out neighboring plants. 

Regular pruning can encourage more flowering, which may easily stretch from spring into the summer. This is another advantage of American wisteria, as its Chinese cousin only blooms once in the spring. American wisteria is deer-resistant and flood-resistant.

Light

American wisteria loves the sunshine and grows best in full sun. It can be grown in partial shade, but these conditions may not allow the plant to bloom. Plenty of sunlight is essential for healthy flowering. 

Soil

Rich, moist, well-draining soil is ideal for this vine. Acidic to neutral pH levels are best. Soil that is too alkaline can cause these plants to become chlorotic, which means the leaves do not produce enough chlorophyll. The leaves will lose their green color and turn a dull shade of yellow.  

Water

American wisteria is naturally found in moist areas by rivers, swamps, or flood plains. Therefore, this vine thrives on consistent moisture. Maintain a regular watering schedule, especially during hot summers when soil may dry out more quickly. 

Temperature and Humidity

American wisteria plants prefer moderate moisture levels but can tolerate high levels of moisture and humidity. It does best in moderate climates, as indicated by its suitability for USDA hardiness zones 5 to 9.

Fertilizer

Adding fertilizer will encourage blooming, which may take up to five or more years to occur. Be sure that your fertilizer contains a good amount of phosphorus, as this will help encourage blooming. Beware of fertilizer that is high in nitrogen.  

Is American Wisteria Toxic?

All parts of this vine contain lectin and wisterin glycoside, which is toxic to humans and animals. The seed pods contain the most concentrated amounts, so removing seed pods may be a good idea if you have curious pets or children.   

Symptoms of Poisoning

If ingested, American wisteria may cause nausea, vomiting, diarrhea, and can even be fatal if ingested in large amounts. In humans, it can also cause problems with speech or dizziness.

American Wisteria Varieties

  • 'Nivea': This variety produces short clusters of white flowers. Its main bloom appears in the summer, but this vine is known to sporadically bloom afterward. 
  • 'Amethyst Falls': As suggested by the name, Amethyst Falls produces beautiful purple flowers with a light fragrance. This variety blooms at a younger age, making it a good choice if you're in a hurry for a flowering wisteria plant. 
  • 'Alba': Another variety with white blooms, Alba produces large white flowers in short, full clusters.  

Pruning American Wisteria

This plant only flowers on new growth, which makes regular pruning key in keeping your large vine full of blooms. Prune the vine in late winter by cutting back at least half of the prior year’s growth.

You may wish to continue trimming back new shoots in the summer to encourage thicker blooming. After blooming in the summer, cut back that year’s growth to around 6 inches. This will help control the vine’s growth, as well as encourage thick blooming. 

Propagating American Wisteria

Using cuttings is the best way to propagate wisteria. Seeds can also be used, but these take years to mature and flower which makes cuttings the quickest and most ideal way.

Be sure to take cuttings from softwood, which is wood that is still green and has not developed woody bark. Annual pruning is a perfect time to propagate. Instead of tossing pruned stems, you can propagate a new plant with them.

  1. Using a sharp pair of garden snips, trim a softwood cutting about 3 to 6 inches long with healthy leaves. 
  2. Remove any leaves on the lower half of the cutting. Remove any flower buds. 
  3. Dip the cut end in rooting hormone and bury it in moist potting soil. 
  4. To hold in moisture, place a plastic bag over the cutting, propping it up with stakes or sticks. 
  5. Place in bright, indirect light. Water when the soil feels dry to the touch. 
  6. Roots should form in about a month. Remove the bag and keep your cutting in a sunny area before transitioning it to a new planting location.