Hubrichtii Amsonia
Hubrichtii Amsonia
Steel-Blue Spring Flowers and Spectacular Golden Fall Color
Threadleaf Bluestar (Amsonia hubrichtii) is a three-season standout that earned Perennial Plant of the Year honors. Clusters of soft steel-blue, star-shaped flowers top the plant in late spring, the fine, thread-like green foliage forms a soft, ferny mound all summer, and then the whole plant turns a blazing golden-amber in fall that rivals any shrub. Tough, drought-tolerant, and deer-resistant once established, it's a low-care anchor for sunny borders in Eden Prairie, Plymouth, and Eagan.
| Attribute | Detail |
|---|---|
| Botanical Name | Amsonia hubrichtii |
| Mature Size | 2.5–3 ft tall and wide |
| Hardiness Zone | Zone 4–9 (hardy across most of Minnesota) |
| Light | Full sun to part shade (best fall color in sun) |
| Bloom Time | Late spring |
| Flower Color | Soft steel-blue stars |
| Soil | Average, well-drained; tolerates drought once established |
Landscape Uses
Use Threadleaf Bluestar as a specimen, in mixed and pollinator borders, prairie-style plantings, and mass plantings where its fall color can shine. Its ferny texture pairs beautifully with coneflowers, grasses, and bold-leaved perennials.
Best Time to Plant
Plant in spring or early fall, when cooler weather and steady moisture help roots establish.
How to Plant
Dig a hole twice as wide as the root ball and just as deep. Set the crown level with the soil, backfill, water in well, and mulch 2–3 inches deep, keeping mulch off the stems.
Watering
First Year: Water deeply 1–2 times per week to establish the roots.
After Year One: Water during dry spells. It's quite drought tolerant once established.
Drip Irrigation: A drip line provides efficient moisture during establishment.
Frequently Asked Questions
What makes Amsonia special?
It offers three seasons of interest: blue spring flowers, ferny summer foliage, and brilliant golden fall color.
Does it need full sun?
It grows in sun to part shade, but full sun produces the most intense fall color.
Is it hardy in Minnesota?
Yes, hardy to Zone 4 and reliable across most of the state.
Is it deer resistant?
Yes, the milky sap makes it unappealing to deer.
You May Also Like
Pair Threadleaf Bluestar with coneflowers, ornamental grasses, and our compact Blue Ice Amsonia for a textural, low-care border.
How Many Hubrichtii Amsonia Do I Need?
Threadleaf Bluestar matures into a soft, shrub-sized mound, so it works as a single specimen or planted in groups of 3 for a textural mass. Space plants about 30 inches apart.
| Bed Run | Plants Needed (30 in spacing) |
|---|---|
| 10 ft | 4 |
| 20 ft | 8 |
| 30 ft | 12 |
| 40 ft | 16 |
Hubrichtii Amsonia Season-by-Season in Minnesota
- Spring: Clusters of soft steel-blue, star-shaped flowers top the plant in late spring and feed early bees.
- Summer: Fine, thread-like green foliage forms a soft, ferny mound with standout texture.
- Fall: The whole plant turns a blazing golden-amber that rivals any shrub.
- Winter: Cut the dormant stems back; it returns reliably each spring.
At a Glance
✔ Pollinator-Friendly ✔ Deer-Resistant ✔ Drought-Tolerant
Plant It With
- Blue Ice Amsonia — a compact bluestar that echoes the blue flowers in a smaller package.
- Sombrero Granada Gold Coneflower — bold gold daisies that pop against the ferny green texture.
- Little Bluestem — a native grass whose fall color complements the amber turn.
- Karl Foerster Feather Reed Grass — vertical lines behind the rounded mound.
Is Hubrichtii Amsonia Right for Your Yard?
It thrives in full sun and average, well-drained soil, where it delivers the most intense fall color with almost no care. Not a fit if your spot is deep shade (it flops and the fall color fades) or very tight — plan for a soft three-foot mound.