Centaurea montana Perennial Bachelor's Button Description Deep blue flowers in June on this bushy plant. In July, cut old stems to base and it will rebloom in August. A durable plant that thrives on neglect, we even had one growing in the cracks of our outdoor stairwell. Popular as a cut flower. Characteristics Hardiness Zone: 3-8 Light requirements: Sun Height: 20" Native: No Sizes & Prices Size: 2 Yr $12.98 Other Information All Bachelor's Button, Perennial Perennial Bachelor's Button Centaurea montana Zone: 3-8 Sun HT: 20"