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Eastern blue star

Flowers of eastern blue star

Eastern blue star is a long-lived, interesting perennial native to central United States. Erect clumps of deep green, willow-like leaves add structure to the garden, steel blue star-shaped clusters open in late spring and foliage turns a beautiful golden yellow in the fall.

This plant has some cultivated varieties. Go to list of cultivars.

 

Botanical name:

Amsonia tabernaemontana

All Common Names:

Eastern blue star, eastern bluestar, willow amsonia, blue dogbane, blue stars

Family (English):

Dogbane

Family (Botanic):

Apocynaceae

Tree or Plant Type:

  • Perennial

Native Locale:

  • North America

Landscape Uses:

  • Container,
  • Hedge,
  • Massing,
  • Mixed border,
  • Patio/sidewalk,
  • Specimen

Size Range:

  • Large plant (more than 24 inches)

Light Exposure:

  • Full sun (6 hrs direct light daily),
  • Partial sun/shade (4-6 hrs light daily)

Hardiness Zones:

  • Zone 3,
  • Zone 4,
  • Zone 5 (Chicago),
  • Zone 6,
  • Zone 7,
  • Zone 8

Soil Preference:

  • Moist, well-drained soil

Tolerances:

  • Occasional drought,
  • Occasional flooding

Season of Interest:

  • Mid spring,
  • Late spring,
  • Early summer,
  • Late summer,
  • Early fall,
  • Mid fall

Flower Color & Fragrance:

  • Blue

Shape or Form:

  • Mounded,
  • Narrow,
  • Upright

Growth Rate:

  • Slow

More Information:

Size

Erect, stiff clumps of willow-like leaves reaching 2 to 3 feet high and 3 feet wide

Tree & Plant Care

Requires full sun to light shade in moist, fertile soil.
Tolerant of dry conditions once established and temporary flooding
Prune back to ground in early spring.
Faded flowers can be pruned in summer to prevent seed development.
Stems contain a milky sap that can be a skin irritant
Staking may be required in too shady conditions

Disease, pests, and problems

None serious

Disease, pest, and problem resistance

Deer

Native geographic location and habitat

Native to central U. S. from MA to KS into south GA to TX in open, moist woodlands and along stream banks

Attracts birds, pollinators, or wildlife

Butterflies, hummingbirds, and bees

Leaf description

Alternate, willow-like, oval to elliptical 3/4 inches wide and 2 to 4 inches long
Dark green with a pale white to green midrib, fall color is an outstanding clear yellow

Flower description

Dark blue buds open to periwinkle to steel blue, drooping clusters of star-shaped flowers
Blooms in late spring to early summer
Stems contain a milky sap, if ends are dipped in boiling water to seal flower stalks they make long-lasting cut flowers

Fruit description

Narrow seed pods appear in pairs
Seeds can be a problem; shear off fade flowers to prevent seeds from forming

Cultivars and their differences 

Blue Ice Eastern Blue star (Amsonia 'Blue Ice'): compact, mounded form reaching 18 to 24 inches high and wide; dark blue buds open to dark blue flowers

Willow-leaf Blue Star (Amsonia tabernaemontana var. salicifolia):  upright, erect habit, 24 to 36 inches high, blue flowers with a white throat

Ozark Blue Star (Amsonia illustris): A southwest native with shiny, broad leaves reaching 3 feet high; light purple-blue flowers

Location of Amsonia tabernaemontana (Eastern blue star) at the Arboretum