True. And even better advice is to not plant them where they will be a bitch to remove if (when) they get frost bit some year and die. When they do get frozen, you can chop them off right at the base and they will usually come booming back, but the old dead thorny vines can be a real bastard if they are grown into something where they are hard to remove. A chain link fence is a nightmare example of a bad place to let these cover. This one happens to be in a pot out on the barbeque deck and I keep it trimmed pretty small, so it can be moved inside if we get a frost.