Rose pruning is one of the most common timing questions in a New Zealand garden, and the plant itself gives a clear answer if you look at when it naturally goes dormant. Roses die back and become properly dormant over winter, and that dormant window is the standard, correct time to prune, rather than any time growth happens to be visible.
In most of New Zealand, that means pruning hard in June and July, while the plant is fully dormant. Pruning earlier than that carries a real risk: it can trigger new growth before winter's cold snaps are done, and that tender new growth is then vulnerable to frost damage. Waiting for genuine dormancy, rather than pruning as soon as the last flowers finish in autumn, avoids that risk.
Pruning earlier than that carries a real risk: it can trigger new growth before winter's cold snaps are done, and that tender new growth is then vulnerable to frost damage.
The actual cuts follow a few standard principles. Cut to an outward-facing bud wherever possible. This encourages new growth to head away from the centre of the bush, keeping the middle of the plant open rather than congested, which improves airflow and helps keep problems like black spot and powdery mildew under control through the following season. Remove dead, damaged, crossing and weak growth first, since none of that wood is worth keeping regardless of overall shape. Crossing branches are worth taking out even if they look otherwise healthy, since branches that rub against each other create wounds that let disease in.
For hybrid tea roses, a rough one-third reduction in overall size is a reasonable starting guideline if you're not sure how hard to cut. It's enough to keep the bush a manageable, productive shape without removing so much wood that it struggles to recover.
Once you've made your winter cuts, clear away fallen leaves from around the base of the plant. Black spot-affected leaves often drop in autumn, and leaving them lying around the base carries the disease over into the next season rather than breaking the cycle.