Posted: 28/03/2013 at 13:06
Highland Jennie, hiya again.
I too grow persicara red dragon...love it.
It does suffer from frosts....can you fleece it for a while ?
I regularly split or chop pieces from it ...pot them up or plant them out. Nice with artemisia Powys castle or aster frikartii
Your lobelia too doesn't like frost. I used to sell plants and regularly dug this up, separate into small pieces and pot up. If me, I would dig it up, split and grow on in the greenhouse....treat as tender perennial. But, watch watering.....they love water. I have grown this in a pool where it thrives