Now, if it needs it.

You can do it anytime. If you cut it now take care not to expose bare wood because it will not re grow until next spring. My garden is surrounded by ivy and I love it because: a) it stays pleasant green all year round, b) hides all the defects of my old fencing and d) gives me a 100 per cent privacy.

Whenever you decide to cut the ivy be aware of any cables, phone etc, its so easy to snip one by mistake.