For the first year I had a decent amount of Magnum hops. I was wondering when I should cut them back. I've heard that you shouldn't cut them down too early because they send nutrients back down to the roots.
I would use the same time frame as for asparagus. Cut the bines after the first few hard freezes turn all the vegetation brown.
Like flars, I usually wait until mine are mostly brown, which happens in November timeframe here.