The cornflower, also known as Centaurea cyanus , is a popular annual wildflower with large, double flowers in dark purple-brown and is still a 'trendy' shade for garden combinations. Cornflowers bloom from June to September and bring vibrant colour to the garden. Cornflower seeds are popular in wildflower mixtures for colourful fields and bee-friendly borders. They are also a valuable nectar source for bees, butterflies and other beneficial insects.