How to Prune Wisteria in Summer

Wisteria is one of the most spectacular climbers you can grow, famous for its long, fragrant cascades of blossom in late spring and early summer. But if left to its own devices, it can quickly become a tangle of stems with more leaves than flowers.

The secret to keeping wisteria healthy, tidy and full of blooms is knowing how to prune wisteria in summer. Typically it's best to tackle the prune in August as this will encourage flower production the following year.

In this guide, we’ll walk you through exactly why and how to prune wisteria in summer, plus tips to keep your plant thriving year after year.

Why You Should Prune Wisteria in Summer

By the time summer is in full swing, your wisteria will have finished flowering and started producing long, whippy green shoots from the current year’s growth. If these are left uncut, the plant will channel its energy into leafy growth instead of flower bud production.

Summer pruning helps to:

• Encourage the development of more flower buds for next spring.
• Keep the plant’s size and shape manageable.
• Improve airflow and light penetration, reducing the risk of pests and diseases.
• Train new growth neatly along its supports for better floral coverage.

A handy way to remember the timing is the gardener’s rule: “7 in 7” for summer (cut back to seven leaves in July/August) and “2 in 2” for winter (cut back to two buds in February).

How to Prune Wisteria in Summer

Step 1: Identify the Current Year’s Growth
Look for the long, pale green, flexible shoots that have grown since flowering. These are easy to spot as they differ in texture and colour from the older, woody framework.

Step 2: Shorten the Shoots
Using clean, sharp secateurs, cut each new shoot back to around five or six leaves from the main stem. This keeps the growth compact and channels energy into flower bud development close to the main branches.

Step 3: Remove Any Dead or Diseased Wood
As you work, remove any stems that are damaged, diseased or dead to help the plant stay healthy and vigorous.

Step 4: Avoid Pruning Old Wood in Summer
Do not cut into thick, woody stems at this time of year. Any major structural pruning is best left until winter when the plant is dormant.

Step 5: Train New Growth
If your wisteria grows on a wall, pergola or arch, tie in flexible shoots to the support structure to guide growth and ensure good flower coverage next season.

Tools and Aftercare

• Use clean, sharp secateurs to make neat cuts and reduce the risk of spreading disease.
• Disinfect your tools before and after pruning.
• Water well in dry spells, especially if your plant is newly established.
• Apply a high-potassium feed in spring to boost flowering.

Common Mistakes to Avoid

• Skipping the summer prune – this can result in fewer flowers the following year.
• Over-pruning in summer – cutting back too hard now can stress the plant.
• Letting stems tangle – untrained growth can become knotted, making future pruning more difficult.

Final Thoughts From Mail Order Trees

Knowing how to prune wisteria in summer is essential for keeping this stunning climber in top condition. By cutting back the long new shoots to around five or six leaves and training any useful growth, you’ll be setting the stage for a spectacular floral display next year.

When combined with a winter prune in February, this summer cut ensures your wisteria stays healthy, well-shaped and covered in blooms for many years to come.

FAQs – How to Prune Wisteria in Summer

Q: When exactly should I prune wisteria in summer?
August is ideal, though late July is fine if flowering has finished and new shoots have developed.

Q: What happens if I don’t prune my wisteria in summer?
You’ll get lots of leafy growth and far fewer flowers the following year.

Q: Can I hard prune wisteria in summer?
No, save any major cuts or reshaping for winter when the plant is dormant.

Q: How do I know which stems to cut?
Target the long, thin green shoots from the current year’s growth, leaving around five or six leaves on each.

Q: Can I prune in September instead?
Early September is fine if you miss August, but avoid leaving it too late to prevent removing developing flower buds.