Centaurea iberica aka Iberian Knapweed

Centaurea iberica has two common names: Iberian knapweed and Iberian star thistle. It belongs to the daisy family, Asteraceae. Its native range spans southeastern and eastern Europe and parts of Asia. It reaches Xinjiang and the western Himalaya. Kew places it in the temperate biome, a broad climate zone. The RHS states it is not native to Britain or Ireland.

This short-lived plant grows as an annual or biennial. These forms live for one or two years. Plants for a Future describes the biennial form. It gives a height of about 3 feet [0.9 metres]. The species blooms from July to August. Each flower has both male and female organs. Bees, flies, moths and butterflies help pollinate the flowers. The plant is also self-fertile: it can use its own pollen. The supplied sources give no fruit or leaf-shape details for this species.

Grow this species in full sun, not shade. It grows in normal garden soil, including sand, loam and clay. For best growth, use rich soil that drains well. It also copes with poor soil and dry ground. Soil can be mildly acid, neutral or mildly alkaline. The plant accepts dry or moist sites and withstands drought. Plants for a Future lists USDA hardiness zones 5–9. Its account of wild sites includes mountain slopes in Tibet. These sites lie at 1,640–2,625 feet [500–800 metres].

Plants for a Future lists garden beds as a growing site. It also warns that the species may become a weed. Keep that warning in mind when choosing where to grow it. The supplied evidence does not show how invasive it becomes. Sow seed in April in a cold frame. Move young plants into their own pots when large enough to handle. Plant them outside in summer. The supplied evidence names no pest or disease problems for this species.

Plants for a Future gives this species a low food-use rating. It lists leaves as edible. Yet its cooked-food note does not name the plant part. The food-use account is thus less clear than the rating suggests. The source lists no known hazards, but that does not prove safety. It records Turkish folk uses for pain, fever, headaches and wounds. It also notes research on antioxidant and antimicrobial effects. These concern oxidation and microbes. These reports do not establish a safe home treatment.