Q How do I prune buddleia (butterfly bush)?

A When Which? Gardening magazine trialled different pruning methods for buddleia, we found the following method produced the best results. Plants pruned this way start to as flower at the same time as plants pruned once in spring, but carry on for a week or so longer. There’s also a bonus second flush of flower heads around 25cm long in late summer, when the size of buddleia flower heads has generally shrunk to 12cm long.

Caption: It's well worth pruning buddleia for a great display of flowers.

How to do it

• Shorten all the branches to 45cm above soil level in early spring, pruning above an outward-facing bud
• Cut all the branches back to 45cm again in May.
• Deadhead continually as the flowers fade.

Caption: Pruning buddleia twice produces the best results.

Q Is it worth deadheading buddleia?

A Definitely. There were 50% more flowers on deadheaded plants and they were all over the plant, rather than just at the top. In the first year of the trial, the deadheaded plants also flowered for a week or two longer than ones that weren't deadheaded.

Caption: Deadheading will give you more buddleia flowers.