There is great diversity among shrub roses but most require only light pruning. Many flower just once in summer and will bloom freely for years with little formal pruning
Creating the shape
Unlike bush roses (hybrid teas and floribundas), shrub roses generally flower on older wood and should be allowed to develop naturally, maintained by light but regular pruning and with a balance of older wood and young, vigorous growth.
Bear in mind that a large number of old garden roses have an arching habit and need adequate space; shortening stems simply to restrict spread spoils their graceful shape.
Single-flowering shrubs
With single-flowering shrub roses, prune in late summer once flowering is completed. The main requirement is to keep the plants free of dead, diseased and damaged wood, crossing or rubbing branches (left), or spindly growth. Prune the main stems lightly. Avoid excessive build-up of older, unproductive wood that is causing the centre to become crowded. If they become leggy and bare at the base, the removal of one or two stems, back to near
ground level, will usually encourage new basal growth.
Repeat-flowering shrubs
On established repeat-flowering shrub roses, maintain a balanced framework by reducing strong new growth by up to one-third (left) and shorten strong laterals to two or three buds in late winter. Mature plants require a light renewal pruning each winter by cutting some of the older main stems back to the base. This encourages vigorous new basal
shoots that will flower the following summer.
When planting shrub roses, prune out dead, damaged or weak growth in spring but leave the remaining strong stems unpruned.
Tony Dickerson