Centaurea was once a common farmland weed, but breeding has turned it into a colorful annual for flowerbed or cutting. The tall group of Centaurea Cyanus reaches 2. 5 feet to 3 feet. The blue Diadem is a good choice with its large deep blue flowers. Dwarf group grows only about one foot and the best one to pick is the Polka dot. The blue varieties are grown for use in arrangements.
Water regularly in dry weather.
Sow seeds in September or April where they are to flower.
Centaurea are best in cool districts and will do well in almost any climate, provided the soil is on the alkaline side.
Dead head regularly.
Stake tall varieties.
Centaurea thrives in sun or partial shade. Flowers in June-September. Keep watch for mildew and aphids to which Centaurea are particularly prone.
Any well drained garden soil.
Scientists were able to revive a flowering plant from the fossilized fruit found in the stomach of an Arctic ground squirrel who was trapped in ice around 32,000 years ago.