When and how to prune Hibiscus or Althéa?

Hibiscus syriacus, also known as Althea, is an attractive bush that can reach 2 to 4 metres in height and adds colour and appeal to your garden with its large flowers ranging from pure white to deep pink, through pink, red and purple. It is an easy-to-maintain bush often used in gardens. However, to keep it floriferous and in good condition, regular pruning is important. In this tutorial, we will guide you through the steps of pruning garden hibiscus: when are the best times to prune and how to prune an Althea correctly?

When and how to prune Hibiscus or Althea?

When to prune Hibiscus?

Hibiscus syriacus can be pruned at different times of year, depending on pruning objectives and climate conditions. Flowering of hibiscus occurs on new shoots. Pruning in late winter–early spring, although not essential, helps control growth, stimulates flowering and maintains plant shape.

Note: it is important not to prune Hibiscus syriacus when temperatures are very low or when frost is present, as this can damage the plant.

Pruning in autumn can help control growth and prepare the plant for winter by removing dead and damaged stems.

Finally, if you want to train your Hibiscus into a tree, follow our step-by-step tutorial: Train a hibiscus into a tree

How to prune Hibiscus?

The process of pruning hibiscus consists of cutting out dead, damaged or unnecessary stems to stimulate growth of new shoots and encourage abundant flowering. If you want to reduce the plant's height and width, you can do so at the same time. Otherwise, let your Hibiscus retain a natural habit. Here are the general steps to prune Hibiscus syriacus:

Prepare your tools: disinfect your pruning shear with alcohol to avoid disease transmission
Remove dead and damaged stems
Remove excess stems from the centre of the plant to improve air circulation

If you wish to control height and width of your bush, cut stems to about 30–45 cm in height on a slant to encourage growth of new shoots. Do not prune your Hibiscus into a ball or a cube; keep as natural a shape as possible.

How to prune a Hibiscus or Althea — Using a pruning shear, make a clean angled cut just above a node

A profusion of vigorous new shoots will regrow on your bush. It will develop a dense, harmonious habit and will bear many flowers in succession throughout the whole growing season

How to cut back a Hibiscus?

If your Hibiscus has become too large or too old, you can consider cutting it back, bearing in mind that cutting large-diameter branches is always harmful to bushes, as it creates an entry point for pathogenous organisms.

Prepare your tools: disinfect your pruning shear and your loppers with alcohol to avoid disease transmission. Use an arborist saw for the largest branches.
Choose three or five strong scaffold branches, well placed and widely divergent. Cut them to approximately 30 cm from the ground and remove all other branches. Always prune at an angle to allow water to run off the wound created.