If you're wondering when and how to prune buddleja, you need these expert tips

These expert buddleja pruning tips will help you keep your butterfly bush luscious and blooming all summer

Buddleja pruning gardener's world
(Image credit: Getty/Jacky Parker Photography)

These buddleja pruning tips  are the only tips you really need to encourage strong growth and plenty of blooms on your butterfly bush come summer. Buddlejas are a joy to grow and one of the best bee-friendly plants for your garden. They're great for butterflies, too – planting a buddleja is one the best ways to create an eco-friendly garden. 

Pruning buddleja really isn't very difficult, but there are a couple of things to bear in mind that will make a dramatic difference to how well your plant is doing and how many flowers it produces. Follow these gardening expert tips for best results. 

1. Don't be afraid of pruning too hard

Buddleja with a butterfly

(Image credit: Getty/Jacky Parker Photography)

Probably the most important thing to know about buddleja pruning is that it really doesn't mind being pruned quite hard. Experts from Gardeners' World say: 'Don’t worry that you’re being too brutal, as buddleja is so vigorous that it will quickly re-grow.' 

In fact, you can prune it quite close to the ground, leaving just five or six strong, thick branches. It may look like you've killed your buddleja bush, but actually, you're encouraging strong new growth on the old wood, which will appear in only a few months. 

Even if you're not ready to do a hard prune, make sure that you 'thin out any crossing branches to prevent rubbing, and remove any thin twiggy growth sprouting from the base.' Use the best secateurs for the job – they should be sharp and used flush with the main trunk 'to minimise the chance of dieback.'

2. Make sure you're pruning the correct variety

Buddleja 'Buzz 3 in 1'

(Image credit: Thompson & Morgan)

The classic butterfly bush can be hard-pruned from late February onwards. Monty Don advises: 'If you live in the south [of the UK] or a sheltered area now is the best time to prune the Butterfly bush, ‘Buddleia davidii’, and it can be done any time in the coming month in colder areas.'

However, there are a couple of varieties you shouldn't hard prune in early spring, or you'll see no flowers at all this year. These are 'Buddleja alternifolia and Buddleja globosa'. They bloom on stems made in the previous season, so cutting them back in spring would remove the flower buds. However, all other varieties are safe to prune and should produce up to three metres of new growth with flowers by summer. 

Did you know that buddlejas are a great plant for front gardens? See more front garden ideas in our gallery to get inspired to give the front of your home a new look. 

3. Prune later for a late flowering to benefit more butterflies

Buddleja bush

(Image credit: Getty/Jacky Parker Photography)

You can prune your buddleja bushes now for the traditional summer flowering from July onwards. However, for anyone who would like to see late-summer butterflies such as the small tortoiseshell: prune your buddleja in May instead of March. 

This will shift the flowering into late summer and early autumn – buddlejas are tough and often will continue flowering well into September and even October in milder climates. If you have multiple buddlejas in your garden, you can prune one or two later to help pollinators throughout the summer. This is a handy tip to bear in mind when pruning shrubs.

In fact, the British Trust for Ornithology advises that 'it is possible to produce a succession of flowering across several plants by pruning one in January, one in February, one in March and one in early April.'

Anna Cottrell
Anna Cottrell

Anna's background is in academic research – she is the author of London Writing of the 1930s, published by Edinburgh University Press. She is a keen urban gardener and has an impressive collection of house plants.