Be prepared to do a lot of deadheading if you grow the "Butterfly Blue" variety of Pincushion Flower.  It produces tons of flowers in May, and continues blooming throughout the year.  The flower stems grow up to 1' tall.  It is difficult to deadhead the flowers in the spring, because the long stems get all tangled up together.  Pincushion Flower increases in size quickly, and is easily propagated by division.  As its name suggests, it is good butterfly plant.  All of my scabiosas died in the winter of 2003-2004.