Part Sun/Semi Shade lover.  An abundant flowerer. Ultra reliable and when happy can be a playful self seeder.  Invaluable for wildlife giving pollinators giving 4 months of pollen and nectar for bees, hoverflies and butterflies and providing winter shelter for ladybirds.   Plant in good sized clumps in groups of 3 to 5 per metre.  This plant is wonderful for straddling the seasons and providing long periods of interest. 
Flowers from Late Spring to Late Summer.  Eventual height 60cm.  Happiest on moist,  shaded soils shining out like ruby coloured stars.
 
This is a hardy perennial meaning it will die back in Winter but will survive any winter conditions and return the following years.   Allow to die back naturally however deadheading spent flowers will dramatically increase flowering.