Butterfly bush, Buddleia: how to prune it well?

Why prune the Buddleia?

Buddleia is a fast-growing bush that flowers on the wood of the year. If left unpruned, the butterfly bush will eventually become bare at the base. Furthermore, it will prefer to produce wood and foliage instead of flowers, resulting in a lanky and unbalanced habit. Pruning the buddleia helps to stimulate flowering, encourage the regrowth of branches, and maintain an elegant and balanced habit.

Don’t be afraid to prune the butterfly bush severely, as it grows quickly and flowers on the new branches of the year.

Pruning Buddleia is done once a year

When to prune the butterfly bush?

The first question to ask yourself is when to prune buddleia, as the pruning period depends on the species! Indeed, depending on the variety, they do not all have the same needs.

When to prune Buddleias davidii (the most common) and Buddleias x weyeriana?

They flower on the wood of the year, that is to say, the new shoots. Pruning of these butterfly trees should be done in February-March, before the start of vegetation. This stimulates abundant flowering in summer.

When to prune Buddleias globosa and Buddleias alternifolia?

These varieties flower on the wood of the previous year. Therefore, pruning of these buddleias should be done after flowering (in summer) to avoid cutting the buds that will produce flowers the following year.

Light pruning of the butterfly tree can be carried out in May-June to delay the blooming of flowers. You can also, as shown here, prune the faded flowers to encourage a second flowering.

How to prune the butterfly bush?

More than other species, Buddleia davidii needs to be severely cut back each year at the end of winter during its dormant period. Other species such as B. alternifolia, B. colvilei, B. farreri, and B. globosa require less drastic pruning. This necessary pruning of butterfly bushes is risk-free, as Buddleias flower on the wood of the year, so you will not jeopardise the upcoming flowering; on the contrary, you will stimulate it!

Olivier shows you why it is important to prune the butterfly bush and the techniques in this video:

Severe pruning of the butterfly bush at the end of winter

Rejuvenation pruning of buddleia allows for the regeneration of an old bush or a bush that has become too large, thus restoring its vigour and good form.

• Cut back all the branches to 50-70 cm above the ground using a pruning shear or a well-sharpened loppers.
• Leave only two or three buds at the base of this year’s shoots to create a sturdy framework.
• Remove weak, excessive, or poorly placed branches at ground level.

A potted Buddleia ready to be pruned

Identify the buds or young shoots and prune just above them

Make a clean cut using a sharp and disinfected pruning shear

Remove dead branches and dried inflorescences

The same Buddleia before and after pruning

Maintenance pruning of the butterfly bush

This maintenance pruning involves balancing the shape of your bush and keeping a harmonious habit and good proportion.

• Cut all the previous year’s shoots to 10-15 cm above the old wood, above a pair of buds.
• Remove weak shoots, dead wood, and branches growing inside the ramure at ground level.
• Prune the branches at the top of the bush short and those at the bottom longer.

How to prune the dwarf butterfly bush?

Pruning dwarf buddleias is quite simple, as these bushes require a light pruning in March to harmonise their shapes, but you can also let them grow as they wish.

Pruning the butterfly bush in summer: the right actions

You can also carry out a light summer pruning to delay and stagger the flowering of Buddleias until autumn by cutting back some of the young shoots in May-June before the flower spikes appear. This will have the advantage of triggering a second flowering in late August-early September. You can also deadhead the faded flowers throughout the summer to encourage further flowering.

Remove faded flowers throughout the summer to stimulate continuous flowering of the butterfly bush.