Hi. I'm worried about my potatoe vine (the one with the beautiful pale blue flowers). Temperatures have just gone down to minus 2 overnight here in the Dordogne and last year during worse conditions it only just survived (with fleece) and this summer conditions have been very hot and dry. Through all that its grown and flowered quite well, but has become very leggy, with no new growth at the foot of the plant. It's three years old. I'm intending to prune it in Spring after the cold weather. My question is, how far back can I prune it? Looking forward to any help. jay jay