This is an optional activity - recommended by some, and considered unnecessary by others.
Some shrubs grown for their colourful stems or interesting foliage will benefit from an annual, hard-prune. Multi-stemmed shrubs, including some dogwoods (Cornus), willows (Salix) and Rubus cockburnianus will produce better stem colour, and foliage plants such as Cotinus and Paulownia will produce bigger, better leaves.
This type of pruning is known as coppicing. This is a common practice for ornamental plants that look their best with young growth, rather than tired looking or weaker, older growth. It is also a good way to grow larger shrubs that would be otherwise too big for your garden.All of the stems can be cut back hard (just above a bud when you can see them) to about 10-20cm from the ground. In the case of Rubus, cut right down to ground level. Always try to form a rounded clump of stems, with slightly taller stems in the middle, getting gradually shorter to the outside of the clump. This gives the shrub a more natural appearance as it regrows. If you have several coppiced shrubs close together, consider cutting them each at a slightly different height to create variation.
If you are coppicing each year, as in the case of plants pruned for foliage (as you will probably want to encourage desired leaf growth), prune to a few of buds above the last year's cut.
In the case of shrubs pruned for stem colour, you may leave it longer - every three years for example. This choice depends on how the plant is performing for you.
How to prune
RJB