Written by David S.
Wisteria is a beautiful option for a vining shrub that grows in hardiness zones 5-9. There are a handful of species, and many of them differ in terms of bloom color, length of racemes (flower clusters), and when they bloom. There are two general groups of wisteria; those from Japan and those from China. There are a couple of varieties from America, and we will discuss those further along in the article.
Wisteria Growing Conditions
Light — Full Sun, though they will tolerate partial shade if they receive at least six hours of direct sunlight.
Soil pH — Slightly acidic with a pH of 6.0-7.0
Soil Grade — Well-draining with lots of organic matter. They like to have more water available than most plants but do not like being soggy.
Watering — Wisteria plants need about one inch of water per week, which is about 16 gallons. For young plants, water often, if not daily. Older plants and those established need watering when the top 1/2 inch of soil is dry.
Fertilizing — For plants less than three years old, use a balanced fertilizer — 10-10-10. For plants established and starting to vine, use a fertilizer with more potassium and phosphorus than nitrogen; a 5-10-10 or 8-15-15 is good. The idea is to give the wisteria less nitrogen, which causes leaf growth and help it to focus on producing roots and vines.
Varieties of Wisteria
- Wisteria sinensis — is a Chinese wisteria available in purple or white — Sinensis Alba. Raceme length is about a foot with a sweet scent. Chinese wisteria twine in an anticlockwise direction. Japanese wisteria twin in a clockwise direction.
- Wisteria floribunda — is a Japanese wisteria that is an excellent climbing plant. The coloring of floribunda is more violet than blue, and the racemes are about one foot in length. The plant is quite showy and excellent on a pergola or other supporting structures. Mature wisteria can weigh several hundred pounds, and proper support is essential.
- Wisteria frutescens — is an American wisteria that produces lovely blue to violet blooms on racemes that are about one foot to 14-inches in length. Frutescens is not broad as many Asian wisterias. It is an attractive, dainty plant that you don’t often find in nurseries. It is native to Texas and Florida and appropriate for Southern California landscapes.
- Wisteria macrostachya — has a common name as the Kentucky wisteria. It is another dainty variety like Frutescens but with longer racemes (to 15-inches,) and lovely pale blue flowers. One plus for macrostachya is that it blooms later than most wisteria varieties and makes an excellent addition to a multi-species landscape.
- Wisteria brachybotrys — is a Japanese wisteria with hairy leaves that resemble strands of silk. The racemes on brachybotrys are shorter — about half the length of most wisteria racemes — at around six inches but are very broad. Brachybotrys is one of the earliest wisterias to bloom, making an excellent addition to a mixed-plant landscape.
There are other varieties of wisteria that we have not mentioned. An important note about growing wisteria; it is essential that these plants have proper support. The mature adult plants can weigh several hundred pounds. They should not be allowed to use your home as a support but instead have a heavy-duty trellis or pergola.
Training wisteria is not tricky. Once the plant begins to develop trailing vines, it is ready to start training. Select groups of 3-5 vines and gently twist them into a single vine. Tie the vine to the support structure. Green nursery tape is a good option for securing the vine to the support. You can also use twine but remove the cord periodically as it can cut into the vine.
One of the beautiful aspects of wisteria is the trunk. It will develop later and become the centerpiece of the plant when the wisteria is not blooming. Take care early one to create a trunk that has movement. Direct the trailing vines upwards, but not straight up. These first vines will become extensions of the trunk as they develop. It is also okay to allow the plant to train itself. The result is more chaotic, but there is beauty there too.
TIP — Flowers on wisteria appear on last year’s vine growth. Be sure to prune back long shoots to force the plant to bloom in tighter clusters closer to the trunk.
Once the wisteria has finished blooming, cut back longer vines. Prune the vines above leaf junctures. Prune long vines to around 6-inches from the trunk. You can also prune away vines that are growing toward the trunk. Doing so keeps the growth outward and shows off the vining and trunk of the plant.
Root suckers and Trunk suckers are also removed during the spring pruning.
You can prune wisteria twice per year. Once in the spring after the flowering has ended and again in the fall or winter.
Wisteria plants lose their leaves in the fall. Once that occurs, winter pruning begins. You will see new buds on the branches or long vines. Prune back branches and vines so that 5-6 sets of buds remain. That process will help to shape the wisteria and force the blooming to be close together.
You can also choose not to prune your wisteria. It will continue to bloom, and the long vines will find a way to attach themselves to the support. Doing so creates fuller wisteria and can allow the plant to climb relatively high.
Wisteria plants are legumes that are in the pea family, and while they produce large pods, they are not edible. It can take some varieties of wisteria 10-20 years to bloom. When selecting wisteria from our nursery, look for plants that are grafted or grown from cuttings. Seedling wisteria plants remain juveniles for over a decade and will not bloom until they mature.
A well-trained wisteria is a beautiful landscape plant. They are delightful in bloom. Wisteria can also be trained as a bonsai or left to run wild. There are no rules, and it is up to the preference of the grower to train or not.
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