When and how to prune a Caryopteris?

Caryopteris, commonly known as 'bluebeard' or 'blue spirea', are deciduous shrubs prized for their long summer flowering period. Their small lavender-blue, mauve or pink flowers cluster at the ends of stems, creating delightful nectar-rich blooms from August through October. The deciduous foliage is equally decorative, with shades ranging from dark green, light green, grey-green, golden, silver or variegated depending on the variety. Their leaves release a subtle aromatic fragrance when crushed. It shines as a standalone specimen, in low hedges, rockeries and even mixed borders alongside perennials, roses or ornamental shrubs. This small shrub thrives in sunny locations with well-drained, even dry soil. To ensure abundant flowering and maintain a neat, compact shape, blue spirea requires hard pruning every year.

Discover everything you need to know about pruning Caryopteris perfectly.

Caryopteris clandonensis Heavenly Blue with its beautiful blue blooms

When to prune Caryopteris?

The best time of year to prune Caryopteris is late winter or very early spring, around March or early April. This spring pruning encourages rapid regrowth in April-May. Repeat this annually, even for young plants.

Note: if you live in a cold region, where your Caryopteris is planted in the ground and needs winter protection, you can prune it in October-November. Prune only after flowering has finished. Blue spirea has limited hardiness beyond -10 to -15°C depending on variety. This allows easy covering of the base with winter fleece or mulch until the last frosts. However, regrowth will be less vigorous.

Why prune Caryopteris?

Pruning bluebeard helps maintain a dense, bushy shape. This vigorous shrub grows quickly, so pruning controls its spread and height. Additionally, cutting back ensures prolific flowering to delight both butterflies and gardeners. Another key benefit: it significantly extends the plant's lifespan.

Caryopteris 'Petit Bleu' with its rounded shape and intense blue flowering

How to prune Caryopteris?

Tools: what you'll need

To prune blue spirea, use hedge shears or secateurs. Note that secateurs work better on older specimens with thicker branches. Always disinfect tools with alcohol before use to prevent disease transmission between plants.

Maintenance pruning

Caryopteris - How to prune — A potted Caryopteris ready for pruning

This maintains a dense shape, promotes abundant flowering and extends your Caryopteris's lifespan. This shrub actually benefits from hard pruning! It's a simple task even for beginner gardeners.

Using shears or secateurs, cut stems back by half, or even two-thirds, shaping a rounded bush 15-20cm high.

Our tips for pruning Caryopteris — Make clean cuts just above a node using sharp secateurs

Remove any dead wood and unsightly branches that spoil the plant's shape.
If your Caryopteris is too dense, thin out some stems.

Pruning Caryopteris — Shorten branches by half or two-thirds, removing dead, awkward or poorly positioned stems

Aftercare

Apply a handful of well-rotted compost or some fertiliser around the base to encourage vigorous new growth.
Fresh green foliage will appear quickly in spring, followed by abundant panicles of blue (or pink) flowers in autumn.
Water moderately if winter has been dry.