Trim your bush

Evergreen trees and shrubs do not lose their leaves in winter and do not store food reserves in their roots. Pruning in autumn and winter could potentially damage the plant, as it can unbalance the root to shoot ratio during a period when it is too cold to regrow. The best time to prune is after flowering. If the plant needs to be renovated, or severely reduced, this can be done late winter and early spring just before growth begins.
Remove old flowers (deadhead)  and cut back to healthy outward facing buds. Remove damaged, diseased, old wood and straggly growth. Take out stems and branches to improve congestion and balance the plant.
Plants can be renovated in late winter or early spring or (for early flowering plants) after flowering.

Some shrubs, if young, vigorous and in good health, can be pruned to almost ground level such as: spotted laurel (Aucuba), box (Buxus), camellias, Choisya, Euonymus, hollies, Pieris, laurels (Prunus laurocerasus and P. lusitanica), Viburnum tinus and yew.
Other evergreens can be renovated over several years:

• In spring lightly prune the whole shrub to encourage buds to break further down the stems.
• Later in summer prune harder into the plant to create the desired size and shape.

After any renovation pruning make sure you feed and mulch in spring, if you want the plant to make vigorous growth.
Shrubs typically produce new stems from the base and some get congested over time if not pruned regularly over several years (especially bush roses). Renovation is best done in stages over three years as follows:

Year 1

During early spring take out a third of old stems (browner stems) close to the base between 5-15cm (2-6in) and cut out completely any spindly, weak-looking or dead stems. Reduce all remaining stems, by about a third, to an outward-facing bud.

Year 2

Take out half the old stems that remain from pruning and prune back the other stems, depending on flowering time, as follows:

• In spring for shrubs with flowers that bloom July - February.
• After flowering for shrubs with flowers that bloom April - July.

Year 3 onwards

Take out all remaining old stems, and repeat pruning as in Year 2.