Wisteria is a beautiful climbing shrub that requires very little maintenance to grow. Its vigorous vines can grow up to 10 feet in a single season, their lilac covering walls, trellises… and unfortunately, also windows and pipes. Here is how to prune wisteria to prevent overgrowth, and actually help make them more beautiful.
Why Should I Prune Wisteria?
If you do not prune your wisteria regularly, you will eventually be left with a large, tangled mass of woody vine and greenery.
Regular pruning not only tames the plants to a more manageable size and aesthetic shape, but helps develop a system of shorter branches, where you can see the flowers and give them enough sunlight to grow.
More vigorous seasonal pruning where you cut back more branches and trim more vines also helps encourage more blossoms and healthy growth.
Once leaves become too overcrowded, they block the flower buds from getting enough sunlight and air. Old branches can take up space and obstruct any new growth.
When Should I Prune Wisteria?
We recommend pruning wisteria at least twice a year, typically in the Summer (July and August) and Winter (January and February).
Trim back the growth to five or six leaves per branch. Remove any root suckers or outlying shoots that are not part of the plant’s main framework. These can compete for nourishment and can make the vines look untamed.
Periodically remove excess leaves that can obstruct flower buds or end up clogging the gutters. You may also want to clear any vines that are encroaching on doors or windows. Some gardeners also like to remove the seedpods, while others leave a few for decorative effect.
We think that winter is the easiest time to prune long runners and vines, since they are free of foliage.
Prepare it for growing season by removing weak, brittle branches and excess growth to allow the stronger buds to get more sunlight and air. Then, prune the remaining runners to about 6 inches (leaving around three buds each). Be sure to cut a little above the last bud.
Older wisteria plants may need “hard pruning” to remove branches that are either worn out, overgrown, or protruding near a window or other structures.
Usually, this maintenance work is based not on season but need or preference: you think the plants look overgrown, or you are concerned about safety hazards.
Maintenance work may require removing everything except the main branches. So, your wisteria plant still looks beautiful, and grows back properly and in the direction, you prefer, plan out your pruning project. Mark branches with string or paint and cut methodically; occasionally stepping back to see if the tree skeleton looks evenly-spaced.
How do I “train” Wisteria through Pruning?
Some gardeners prune wisteria in order to grow into a certain shape or along a preferred structure like a wall, lattice, arbor or pergola. Through selective cutting and propagation, the vines are “trained” to branch out in particular way, from climbing up a vertical structure and then left to hang dramatically at the edge.
Since the wisteria vines are so vigorous, you just need one or two vines to cover a structure. You can also combine different colours of wisteria for a more dramatic effect. While the most common colour is purple or lilac, you can now find wisterias in blue, pink, and white.
If you are planning to train your wisteria, choose a strong post made of metal or cedar, which is less likely to rot than other types of wood. It should be at least 2×4 (though most recommend 4×4) and secure them to the ground with concrete.
In the first year, position 2 to 3 shoots to twine around the post and each other. You will need to secure them with galvanized wire and eye hooks (placed the hooks 16 to 18 inches apart, making sure that they are evenly distributed on all four sides of the post).
You can also use this support network of wire and hooks for growing wisteria on lattices and walls.
As the shoots grow longer, secure them to wire with gardening twine. Allow just enough slack so that they can droop gracefully; remember that as the plant matures, it will also grow heavier and add more tension to the twine.
IN the next few months (and seasons) you will need to periodically prune the wisteria to encourage side shoots to embrace the post or any support structure and encourage the growth of clusters of flowers. During spring, cut the tips to encourage branching.
Remove the training ties when the wisteria vines have become stable enough.
Tips for Pruning Wisteria
- Always prune branches at the node. This is where branches or twigs connect to one another.
- Have a general shape in mind. As a rule, the goal of pruning is to maintain the branches that help maintain or develop the plant shape or structure.
- For winter pruning, wait until the end of the season when temperatures do not drop below freezing. Extreme cold can dry out the incisions. We recommend starting with diseased or dead branches, followed by unwanted low-lying branches as the weather improves. Your goal is to remove at least half of last year’s growth, leaving just 2 to 3 buds per branch or stem.
- For summer pruning, choose a mild sunny day. Aside from the fact that it is pleasant weather for gardening, there is less chance of the tender branches from being affected by cold temperature or water-borne disease.
- For a more elegant and formal look, do a second general pruning in the middle of summer, after the buds have flowered. Clean up any tangled vines or unwanted overgrowths.
- To encourage more flowers to bloom, prune back shoots every two weeks at the peak of summer.
- To help a new wisteria plant flourish, prune a larger section of the vine right after you plant it. Wisteria tends to resprout more vigorously after it has been severely cut. However, leave a few shoots untouched because it takes longer for new shoots to flower.
- To maintain a trained plant, just prune side shoots to about 6 inches in the summer, and then to the length of 3 to 4 buds in the winter.
Regular pruning can bring out the beauty of your wisteria vine. While it may take more time, you will be rewarded by an abundance of flowers and lush but well-shaped growth.
Garden Doctor Tips
“Thomas Nuttall was the botanist that gave Wisteria its name and he said that he named it after American physician Caspar Wistar!”
“Some Wisteria varieties can take up to 20 years to mature and subsequently flower!”
“It is said that some varieties of Wisteria flower are edible and can be used to make wine. Be careful though as many Wisteria flowers are in fact toxic!”
“Wisteria is the ultimate climber and is known to be so strong that it can suffocate tree’s or bring down weak structures!”
Frequently Asked Questions
Can you grow wisteria in pots?
Yes, Wisteria can be grown in pots although it will not become extremely large and overbearing. Growing Wisteria in pots is a great way to keep it under control and prevent it from becoming too large and strong.
Is Wisteria bad for houses?
Although very beautiful, without the right support, Wisteria could easily cause damage to your home. They are an extremely hardy and powerful plant that requires a supporting structure for it to grow onto. If a Wisteria is not given this additional support, it will climb up your house and into each small crack and crevice, damaging windows and guttering.
Is Wisteria easy to grow?
Wisteria is remarkably easy to grow although if you wish for them to flower, you will want to grow them in full sun.
Wisteria do best in fertile, well-drained soil but honestly, they will do well in almost all soil types as long as it is not too high in Nitrogen.