Cranesbills are great groundcovers for sun or partial shade. This blue one was in the long-neglected garden when I moved into my current house, a testament to its toughness. Geraniums come in flower colours of white, blue, pink, mauve and purple.
They bloom in late June and last for several weeks; some varieties will bloom all summer if you deadhead them.
I think this variety might be 'Johnson's blue'. It is getting too big for this spot in the rock garden and isn't flowering much any more, so next spring I am going to dig it up and spread some pieces around the front garden, where I need to fill some space.