A sound cultural advice would be to cut the flower immediately (or rather to have cut it, when it were in bud - but better late than never) to avoid the plant spending energy on flowering, and instead use what it's got on growing/stabilizing.
I speak of bitter experience, as I earlier this year lost my lovely coloured P. villosum var. boxallii fma. atratum, as I out of curiosity let it flower from a way too small and not really well established plant! May it rest in peace!