Posted: 27/03/2015 at 18:39
I grow mine on the edge of my borders. When the flowers start to go tatty in midsummer, cut them back by half and they will come back with another show of flowers. Cut back again in late autumn and they will sprout new shoots around now, when you can cut off any dry stems. They have survived -10°C with no problems here.
Strangly, our cat shows no interest in them at all!