Leave it alone, don't do anything with it now. If you mean Verbena bonariensis, mine are in the same condition, but even if you don't, the advice is the same. Wait till spring and then cut back to wherever is still green. I know it feels like time to do it, but it's not - we're only in early January, and there's plenty of time for some really cold weather to arrive - February particularly can be a pig of a month.

thanks Bamboo for your advice about the verbena. We weren't sure if we should have cut it to ground level last Autumn, and once it sprouted the new green growth were unsure what to do with it, we have 4 tall plants of the kind you mention.So, could I ask further to this, would you have normally cut down your plants in Autumn [if the weather had been normal]?Thanks from Freeasabird.

It`s very tempting to tidy up plants when you see new growth, but with all mine l leave them till it gets warmer and frost clear. it might look messy but old growth will help to protect the new shoots that are appearing.

I don't cut mine down, Freeasabird - I might deadhead during summer, but unless they get broken by the wind, I don't cut them down at all. They're not entirely hardy, so at the very least, leaving some flowers on to set seed at the end of summer is useful. I do, though, cut down those in client's front gardens - they look too tatty otherwise, but I don't mind the tattiness for my own planting. Wherever possible, I leave them till spring and see what's occurring with them then.