Spot a buddleja in summer and you'll see why it's often referred to as the butterfly bush. It's one of the best plants for attracting pollinators and is often covered with butterflies when it's in flower.
Pruning buddleja is easy, providing you know which type you have – different varieties are cut back at different times of the year. Knowing when to prune your buddleja is just as important as knowing how!
Pruning buddleja davidii
Cut old stems back to a pair of good buds in the spring
Image: Thompson & Morgan
Buddleja davidii is the most common variety, identified by the fact that it flowers on this season's new growth. It's a robust shrub but can quickly become untidy if not pruned, with the flowers appearing so high that only the butterflies can enjoy them. Annual pruning keeps it in shape and helps produce more flowers, lower down.
Prune Buddleja davidii in early spring when new growth starts appearing and the risk of a hard frost has passed.
Young shrubs should be pruned to create a short, strong framework of branches that are about 45cm high. If the bush is at the back of a border and you need it to be taller, cut back to make a frame that's anywhere up to 1.2m high.
Prune all the stems using loppers, but leave two or three sets of good buds – this gives you a buffer in case of a late frost. Remove any weak, damaged stems or those that are rubbing against another branch.
In future years, the shrub should be pruned back to this same framework. Buddleja davidii responds well to pruning and neglected shrubs can be rejuvenated by cutting back hard.
Later in the season, deadheading faded blooms back to a pair of strong shoots is worth the effort as it gives a tidier appearance and can result in a second flush of flowers.
If you have Buddleja Davidii or a dwarf variety, like Buddleja 'Buzz', watch our short video at the end of the aricle for a quick guide on spring pruning.
Pruning other buddleja varieties
Some varieties of buddleja, like 'Unique' should be pruned after flowering
Image: Buddleja x alternifolia 'Unique' from Thompson & Morgan
Buddleja alternifolia and Buddleja globosa both produce flowers on old wood, so cutting them back in spring would mean no blooms the following year.
- Buddleja alternifolia should be pruned as it finishes flowering in midsummer. Cut back all the stems that have flowered to healthy buds, to produce flowering wood for the following season.
- Buddleja globosa should be pruned just to maintain a good shape or remove dead and damaged shoots. This is best carried out in late winter before the start of new growth. Pruning removes the flowering stems so limit it to what is essential.
