Blue Star (Amsonia 'Blue Ice') - How to Grow & Care Guide

Plant Snapshot

Common Name: Blue Star
Latin Name: Amsonia 'Blue Ice'
Alternate Names: Blue Ice amsonia
Hardiness Zones: USDA zones 4–9. Colder zones may die back to the crown and regrow in spring. In warmer zones foliage may persist longer into fall.
Typical Height: 12–18 in (30–45 cm).
Typical Spread: 24–30 in (60–75 cm).
Bloom Period: Late spring to early summer.
Soil Preferences: Average, well-drained soil. Tolerates poor soils. Avoid waterlogged conditions which cause crown rot.
Light Preferences: Full sun to part shade. Best flowering and fall color in full sun. Provide some afternoon shade in hot climates.
Toxicity: No major toxins widely documented for Amsonia cultivars but avoid ingestion. Handle with care as sensitive individuals may experience minor skin irritation.
Propagation: Division in spring or fall is easiest. Softwood cuttings and seeds are possible. Seed may not be true to the cultivar.

Key Facts

Herbaceous perennial with star-shaped blue flowers.
Compact cultivar selected for a smaller clumping habit.
Blooms in late spring to early summer.
Prefers full sun to part shade.
Does best in average well-drained soils and tolerates some drought once established.
Foliage often turns golden-yellow in fall.
Attracts bees and butterflies.
Propagate by division or cuttings. Seed may not come true to the cultivar.

Blue Star Amsonia ‘Blue Ice’ is a compact, clumping perennial prized for its clusters of star-shaped blue flowers and late spring bloom. It fills sunny borders and pollinator beds where a low, spreading mound of blue flowers and golden fall foliage is wanted.

Identification and form

Blue Star is a herbaceous perennial with small, star-shaped blue flowers that appear in late spring to early summer. Plants typically reach about 12 to 18 inches tall and form a 24 to 30 inch wide clump. The selection ‘Blue Ice’ is chosen for a tighter, more compact habit than some species forms.

Best uses and where to grow

Use Blue Star in sunny borders, mixed perennial beds, and pollinator plantings where a low mound is desirable. It works well as an edging or in front-of-border planting because of its low height and seasonal interest. Give it room to form a 2 to 3 foot clump to show its best shape.

Planting and spacing

Plant with enough room for the eventual spread by spacing transplants about 24 to 30 inches apart so clumps can develop. Set plants so the crown sits level with the finished soil surface and firm soil around roots. In new beds work in organic matter to improve establishment without creating heavy, waterlogged conditions.

Soil and light

Blue Star performs best in average, well-drained soils and tolerates poorer, drier soils once established. Avoid waterlogged locations that can cause crown rot. Give full sun to part shade; best flowering and brightest fall color occur in full sun, while afternoon shade helps in hot, humid climates.

Watering and maintenance

Water regularly until plants are established, then reduce irrigation as Blue Star tolerates some drought. Persistent wet soil causes decline. Mulch to conserve moisture but keep mulch away from the crown. Divide clumps every few years to renew vigor and keep the habit compact; dividing also controls the natural spread over time.

Wildlife and season interest

Clusters of blue flowers attract bees and butterflies in late spring to early summer and provide pollinator value. Foliage often turns a golden-yellow in fall, adding seasonal color to the garden. The combination of spring flowers and autumn foliage makes it useful for two-season interest in perennial schemes.

Propagation and spread control

Division in spring or fall is the easiest method to propagate and maintain compact clumps. Softwood cuttings can preserve cultivar traits, while seed may not come true to ‘Blue Ice’. Expect the clump to widen over several seasons and divide periodically to control spread and refresh plant vigor.

Frequently asked questions

How fast does Blue Star grow?: Blue Star spreads gradually, forming a 24 to 30 inch clump over several seasons while reaching 12 to 18 inches tall. Growth is typically slow to moderate in average garden soils.
What months does Blue Star bloom?: Blue Star blooms in late spring to early summer, typically May to June in temperate Northern Hemisphere climates. Exact timing shifts with local climate and latitude.
What soil does Blue Star prefer?: It prefers average, well-drained soil and tolerates poorer soils. Avoid heavy, waterlogged ground which can lead to crown rot. Mulch is helpful but keep it away from the crown.
How should I propagate Blue Star?: Divide clumps in spring or fall to propagate and rejuvenate plants. Softwood cuttings work to maintain cultivar traits. Seed is possible but may not be true to the ‘Blue Ice’ cultivar.
Is Blue Star hardy where I live?: Blue Star is generally reported hardy in USDA zones 4 through 9. Use local extension services or suppliers to confirm performance in marginal or colder sites.