Centaurea montana aka Perennial Cornflower

Centaurea montana belongs to the daisy family, Asteraceae. It is a perennial: it lives for more than two years. Its names include mountain bluet and perennial cornflower. It comes from Europe's mountains, including those in southern Europe. It grows in mountain meadows and at the edges of woods. It is not native to Britain or Ireland. Its leaves die back with the seasons.

Plants grow in upright clumps and spread through creeping stems. Garden height ranges from 1–2 feet [0.30–0.61 metres]. North American sources give widths of 1–1.5 feet [0.30–0.46 metres]. RHS gives a wider spread, reaching 3.3 feet [1 metre]. Plants grow fast and can form colonies. Rich soil can make them spread more. Cool northern climates can do the same. The straight, hairy stems tend to have few or no branches. Soft, grey-green leaves grow in turn along the stem. Lower leaves have a lance shape and toothed edges. They can reach 0.58 feet [0.18 metres] long. RHS also notes leaves with lobes and hairy undersides.

Blue flower heads have fringed outer parts and reddish centres. Bracts, small leaf-like parts, surround each head and have dark edges. Heads measure about 0.17 feet [0.05 metres] across. The main bloom comes in May and June. Some flowers may return from late summer into early autumn. Bees and butterflies visit the flowers. The blooms also make good cut flowers. Small, dry fruits called achenes form in autumn. They turn the colour of straw and bear fine hairs. Each has a short tuft of stiff, pale brown bristles.

Grow this plant in sun and soil that drains well. RHS also accepts some shade and moist soil with good drainage. Other sources report growth in dry to somewhat moist soil. It copes with drought, poor soil, and several soil textures. It grows in acidic, neutral, and alkaline soil. Avoid rich soil where unchecked spread would cause problems. Remove dead blooms to prolong flowering and reduce seed growth. Divide clumps every two to three years. RHS notes that plants may need stakes for support. Sources rate it for USDA zones 3–8 and UK H7.

Use it at border fronts, in cottage gardens, or in meadows. It can also cover the ground in sunny places. Chicago Botanic Garden notes that it resists deer. Serious pest problems are rare, but disease can occur. Reported problems include mildew, rust, aster yellows, and stem rot. Plants For A Future lists no known edible uses or hazards. This does not prove that eating it is safe. It notes past herbal uses, such as eye washes. These also include remedies made from dried flowers.