Cut the main stems of large bush, tea and hybrid perpetual roses
In late winter to early spring, cut out any dead, damaged or diseased stems first. Then you are left with healthy strong stems.
Cut back main stems to 20-25cm (8-10in) above ground or 45-60cm (18-24in). Reduce sideshoots to two or three buds or 10-15cm (4-6in). Always prune to just above a healthy, outward facing bud with sharp, clean secatures. Remove weak and spindly shoots (less than 'pencil thickness').
For renewal, cut back one-third of the oldest stems almost to the base in the first year. In subsequent years remove a further one-third each year.