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Bluestar
Amsonia
Bluestar blooms from April through May.
Mature size, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not.
Growing Bluestar
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–9. Expect it to reach about 3 ft tall and 2.6 ft wide at maturity, in roughly 3 years.
When to plant Bluestar
Plant Bluestar in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. For the middle of its hardy zones 3 to 9 range, spring means March to May and fall means August or September. Once settled, it blooms from April to May.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 6 in March.
Good to know about Bluestar
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
When cut, stems and leaves ooze a milky white latex that is mildly toxic and can irritate sensitive skin. Wear gloves and keep the sap off skin and eyes. per NC State and Wisconsin
Worth knowing
Full sun does double duty: it produces the strongest gold fall color and the sturdiest, self-supporting habit. The shade that dulls color is what makes stems flop. per NC State and Penn State
When to cut back
Never cut before or during bloom. After flowering, either cut back by a third for a tidy mound, or leave the stems standing over winter for the bees. per NC State and Mt. Cuba
Zone range depends on species
Eastern bluestar is hardy in zones 3 to 9; threadleaf is cited narrower, 5 to 8 or 4 to 9. In zones 3 to 4, confirm your species first. per NC State and Penn State
Deer and rabbit resistant
Deer and rabbits leave it alone: the bitter, toxic milky sap makes the foliage unpalatable. A dependable pick where deer pressure is high. per NC State
Feeds early-season pollinators
Spring flowers draw native bees, hummingbirds, hummingbird moths, and butterflies. It is also a larval host, and hollow stems left standing shelter native bees. per Penn State
Essentially trouble-free
No serious insect or disease problems and no chemical inputs needed. Rust is an occasional, minor possibility. A tough, long-lived, low-maintenance perennial. per NC State
Deep taproot, drought tolerant
A deep taproot makes established plants drought tolerant, yet it also takes occasional wet feet and suits a rain garden. Slow to fill in. per Penn State
What pairs well with Bluestar
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Sneezeweed
Shares full sun and moderate water; blooms in midsummer, extending the bed's season; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Perennial Sunflower
Shares full sun and moderate water; blooms in late summer, extending the bed's season; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Creeping Sedum
Shares full sun and low to moderate water; blooms in early summer as this one finishes; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Lavender
Shares full sun and low to moderate water; blooms in early summer as this one finishes; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Feather Reed Grass
Shares full sun and moderate water; blooms in early summer as this one finishes; its seed heads stand through winter, for structure and the birds; taller at 4.9 ft, for the layer behind it.
Cleome
Shares full sun and moderate water; blooms in early summer as this one finishes; both offer pollinator forage, in different months; taller at 3.9 ft, for the layer behind it.
Passionflower
Shares full sun and moderate water; blooms in midsummer, extending the bed's season; both offer pollinator forage, in different months; climbs to 13 ft behind it, height without the footprint.
Asiatic Lily
Shares full sun and moderate water; blooms in early summer as this one finishes; both offer pollinator forage, in different months; pink against blue, for contrast.
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