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 overgrown 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?
Wisteria should be pruned twice a year for optimal health and flowering. The first pruning should occur in late winter, between January and February, to prepare the plant for the upcoming growing season. During this time, you should focus on removing any dead or diseased branches and shaping the plant. The second pruning should happen in mid-summer, after the flowers have faded, typically around July or August. This pruning session is to control the current year’s growth that can become unruly and to maintain the shape and size of the plant.
Wisteria Winter Pruning Jan/ Feb
To prune wisteria in winter, follow these steps:
- Identify the Main Branches: Locate the main structural branches of the wisteria. These are the branches that form the framework of the plant and should not be cut back drastically.
- Prune Side Shoots: Cut back the side shoots that grew during the previous season to about 2 to 3 buds from the base. These are typically the long, whippy shoots that the plant produces.
- Remove Unwanted Growth: Take out any shoots that are growing in unwanted directions or that are crossing over and rubbing against each other, as this can cause wounds and entry points for disease.
- Shorten Stems: Shorten the stems that you pruned last summer, leaving just a few buds on each stem. This encourages the development of spurs which will bear flowers in the spring.
- Clear the Base: Remove any suckers coming from the base of the plant or any dead or diseased wood.
- Shape the Plant: If you are training the wisteria on a wall or over a pergola, tie in any long shoots that you want to keep to maintain the desired shape.
The goal of pruning and training wisteria is to create a strong framework of branches that will support the weight of the mature plant and its flowers.
Wisteria Summer Pruning July/ August
Summer pruning of wisteria is important for maintaining the structure of the plant, controlling its size, and enhancing flowering for the next season. Here are the steps for summer pruning:
- Timing: Perform summer pruning in late July or August, after the current year’s flowering has finished.
- Identify New Growth: Look for the current season’s growth, which will be long, whippy shoots that have sprouted from the main framework of the plant.
- Prune Back New Shoots: Cut back the new shoots to about five or six leaves from the main branch. This encourages the development of short, flowering spurs.
- Remove Unwanted Shoots: Any shoots that are not needed or have grown in crowded areas should be pruned back to their point of origin or to a suitable side shoot.
- Thin Out Crowded Areas: If some areas of the plant are too dense, thin them out to allow light and air to reach the centre of the plant, which helps to prevent disease.
- Tie-In Desired Shoots: If there are any new shoots that you wish to keep to extend the framework or fill in gaps, tie them into their support.
- Maintenance: Remove any dead or diseased material and any suckers from the base of the plant.
Can Overgrown Wisteria be Hard Pruned?
Yes, wisteria can be hard pruned. This is often necessary to rejuvenate an overgrown plant or to drastically reduce its size. When hard pruning, it’s important to do so during the late winter when the plant is dormant to prevent sap bleeding, which can weaken the plant. Although wisteria is quite resilient and will typically respond with vigorous growth following a hard prune, it’s important to note that this may result in a temporary reduction in flowering, as wisteria blooms on old wood. After hard pruning, the plant will require regular maintenance pruning to manage new growth and to encourage the development of flowering spurs.
It’s also crucial to ensure that the support structures for the wisteria are secure and able to handle the weight of new growth. While hard pruning can be beneficial for controlling and rejuvenating wisteria, it should be done carefully and not more frequently than necessary.
How to Hard Prune an Overgrown Wisteria?
Hard pruning an overgrown wisteria involves cutting back the plant significantly, which can help rejuvenate it and encourage new growth. Here’s how to do it:
- Timing: Perform hard pruning in late winter when the plant is dormant. This reduces the risk of sap bleeding and stress to the plant.
- Preparation: Before you start, ensure that you have clean, sharp tools to make precise cuts and minimise damage to the plant.
- Initial Cuts: Begin by removing any dead, diseased, or damaged wood. Cut these branches back to the base of the plant.
- Main Structure: Identify the main stems or trunks that form the framework of the plant. Decide which ones to keep based on their position and health.
- Reduction: Reduce the length of the main branches, leaving a few buds on each stem. These buds will be the source of new growth.
- Side Shoots: Cut back side shoots to 2 to 3 buds from the base. These will grow and can be trained in the desired direction.
- Thinning: If there are too many stems, thin them out to prevent overcrowding, which can diminish airflow and light penetration, potentially leading to disease.
- Support: Check and reinforce any supports, as the new growth will be vigorous and can become heavy.
- Follow-up Care: After hard pruning, monitor the wisteria during the growing season. Regularly prune new growth to maintain the desired shape and size.
- Patience: Understand that hard pruning may lead to a few seasons without flowers, as wisteria blooms on old wood. However, this sacrifice can lead to a healthier and more manageable plant in the long term.
How do I “Train” Wisteria through Pruning?
Training wisteria through pruning involves several steps to ensure that the plant grows in the desired shape and direction. Here’s a step-by-step guide to help you train your wisteria effectively:
1 – Choose the Right Support
- Select a sturdy post made of metal or rot-resistant wood like cedar.
- Ensure the post is of adequate size, preferably 4×4 inches for strength.
- Secure the post firmly into the ground using concrete for stability.
2 – Initial Training
- In the first year, choose 2 to 3 healthy shoots to train up the post.
- Use galvanized wire and eye hooks to create a support system. Space the hooks 16 to 18 inches apart and distribute them evenly around the post.
- Twine the selected shoots around the post and each other, securing them with the wire and hooks.
3 – Secure the Vines
- As the shoots grow, use gardening twine to tie them to the wire framework.
- Allow some slack in the twine for the vines to droop gracefully, but not too much as they will grow heavier with time.
4 – Prune for Shape and Flowering
- Periodically prune the wisteria to encourage it to cover the support structure and to promote flower growth.
- In the spring, trim the tips of the shoots to stimulate branching, which will result in more flowers.
5 – Maintenance Pruning
- Continue to guide and secure new growth, pruning as necessary to maintain the shape and encourage flowering.
- Remove any dead or unwanted growth to keep the vine healthy and well-shaped.
6 – Remove Training Ties
- Once the wisteria vines have established themselves and are stable, you can remove the training ties.
- Monitor the plant to ensure it continues to grow as desired, making adjustments to the support structure if necessary.
Regular pruning can bring out the beauty of your wisteria vine. While it may take more time, you will be rewarded with an abundance of flowers and lush but well-shaped growth.
Did You Know?
“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 trees 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 extremely hardy and powerful plants that require a supporting structure for them to grow. 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 does best in fertile, well-drained soil but honestly, it will do well in almost all soil types as long as it is not too high in Nitrogen.
Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.