Mountain bluet Centaurea montana Photo/Illustration: Steve Aitken 1 2 3 4 5 6 7 8 9 10 11 Mountain bluet (Centaurea montana) sen-TOR-ee-ah mon-TAN-ah Genus: Centaurea Mountain bluet is an excellent choice for the border or rock garden. Blue flowers open from attractive buds in late spring to midsummer, then leave behind a mass of vigorous, silvery-green woolly foliage and woolly stems. Noteworthy Characteristics: Blue, spidery flowers. Self-seeds. Care: Grow in moist soil in sun or partial shade. Easy to divide in fall if it begins to crowd its neighbors. Self-seeds readily. May need staking. Propagation: Divide in fall. Problems: White mold, rust, downy and powdery mildew, thread blight, and Southern blight can occur. Overview Height 1 ft. to 3 ft. Spread 1 ft. to 3 ft. Growth Habit Spreads Light Full Sun to Part Shade Moisture Medium Moisture Maintenance Moderate Characteristics Self Seeds Bloom Time Early Summer, Late Spring, Spring, Summer Flower Color Niagara Uses Beds and Borders Style Cottage Garden, Rock Garden Seasonal Interest Spring Interest Type Perennials Centaurea montanaView the discussion thread.