Threadleaf Blue Star

Threadleaf bluestar (*Amsonia hubrichtii*) is an upright, clump-forming perennial with very fine green leaves and clusters of powder-blue, star-shaped flowers. Its foliage turns yellow to gold in fall, giving the plant a second season of color ([University of Illinois Extension](https://web.extension.illinois.edu/hortanswers/plantdetail.cfm?PlantID=704&PlantTypeID=2)). ## Landscape Use The fine foliage makes a soft-textured contrast in sunny perennial borders, open woodland edges, and naturalistic groupings. Oklahoma State Extension recommends this species for mass plantings, mixed borders, meadows, native gardens, and open woods ([Oklahoma State Extension](https://extension.okstate.edu/programs/oklahoma-proven/plant-profiles/arkansas-bluestar)). University of Illinois Extension lists a typical mature height of 2–3 feet and spring bloom in May–June. Allow room for a substantial clump and avoid placing it where shade from nearby plants will cause the stems to open or lean. ## Growing Conditions Plant in sun to light shade in well-drained soil. Although it tolerates clay, Iowa State Extension reports that this species prefers drier soil than eastern bluestar (*A. tabernaemontana*); avoid treating all Amsonia as equally moisture-loving. Water regularly while the root system establishes, then water during prolonged dry periods; Oklahoma State Extension reports that established plants are drought tolerant ([Oklahoma State Extension](https://extension.okstate.edu/programs/oklahoma-proven/plant-profiles/arkansas-bluestar)). ## Seasonal Interest Powder-blue flowers appear in late spring above narrow, bright-green foliage. The foliage shifts to yellow-orange or gold in autumn. Deer generally avoid bluestars, whose cut or damaged stems release milky sap ([Iowa State Extension](https://yardandgarden.extension.iastate.edu/how-to/bonkers-bluestars)). ## Maintenance In a shady or floppy planting, shear stems back after flowering to encourage a shorter, more compact outline; this is an as-needed correction rather than a required annual task. Avoid unnecessary division or moving once the dense root system is established.