It is low growing, no more than about 50cm, and spreads about 60-100cm. It's hardy, likes full sun or partial shade and well drained soil (but can grow in pretty much any situation). It can flower between May and September. It may not flower for very long (in our garden with so many bees about it gets about two to three weeks initially as the flowers go to seed quickly), but can flower a second time if cut back after the first flowering.
This year it has been disappointing - all leaves and not many flowers.
Geraniums are sometimes known as Cranesbill or Crane's Bill, because that is what their seed pods can look like (something that is very evident on this variety) and usually have attractive foliage that goes a nice colour in autumn - or earlier, as the colour can emerge anytime after they have stopped flowering.