Centaurea montana, Mountain Bluet,
Hardheads or Knapweed is a sky-blue flowered plant that blooms in late
spring to mid summer.
It is also sometimes known as cornflower,
more because of the resemblance to the flowers of the annual cornflower,
Centaura cyanus, than because it is found in the corn fields as a annual
weed.
This perennial grows from rhizomes and
reaches up to 18 inches, you may find reference to it needing staking
though I never bother with mine and they've yet to fall over.
Can be grown from seed or propagated by
division in spring or fall. Not happy with root disturbance though, even
if grown from seed, so best sown in biodegradable containers that can be
planted whole into the ground.
