cutting back plants?

[jock_edin]

I put some plants in the edges of the allotment this year for ground cover and the best one of which there are a few is Rhodochiton Rudbeckia Var.Speciosa the problem is they need cut back, does anyone know this plant and if so where do I cut, I think probably down near the ground but maybe I leave some stock on ? Willie

[jock_edin]