OOOOOOOOh that's cold Michelle. Verbenas can't handle that kind of cold. I suggest you dig them and other more tender perennials, pot them up and find a place to store them where they won't freeze. Keep the soil just moist. A couple of ice cubes or a handful of ice every few weeks should do the job I know it's said some verbenas are hardy to zone 5, when they do survive, it's usually in a micro-climate. Best and Happy Yardening, Nancy
How To Protect Verbena From Winter Cold
Question From: m. blanchette - MAINE
Q: Hi nancy . i live in northern maine where our temps can go as low as -30% in the winter. i have a 200ft perennial bed and my question is. how do i protect my perennials r on the tender side. exp. perennial verbeana. would a antitranspirent spray work or should i dig them up. and if i do dig them up how do i winter them over.