Amsonia hubrichtii (Hubricht's Amsonia)

A four-season specification perennial known as much for its gold autumn display as its spring bloom, threadleaf blue star pairs genuine deer resistance with low maintenance needs - though its native range means it should be positioned as an adaptable ornamental selection rather than a regionally native one here.

Species Overview

Amsonia hubrichtii, or Threadleaf Blue Star, is an herbaceous perennial known for its fine, needle-like foliage and clusters of pale blue star-shaped flowers that bloom in late spring. In autumn, the foliage turns a brilliant golden-yellow, providing stunning seasonal interest in gardens. This low-maintenance plant thrives in full sun to partial shade and prefers well-drained soils. It is drought-tolerant and deer-resistant, making it a popular choice for borders, rock gardens, and naturalized areas.

Application

• Border and rock garden plantings prioritizing fall color and low maintenance
• Mass plantings for a fine-textured, feathery foliage effect
• Naturalized landscape plantings on well-drained sites
• Deer-pressured sites, where milky latex sap discourages browsing

Growing Conditions / Specification Data

• Light: Full Sun to Part Shade
• Soil/Moisture Tolerance: Well-drained soils; low-maintenance once established
• Drought Tolerance: High
• Flood Tolerance: Low - Adapted to well-drained rocky or sandy soils; not tolerant of standing water.
• Plant Type: Forb
• Mature Height: 2-4 ft.
• Fall Color: Yellow - a signature trait of this species, described as "brilliant golden-yellow"
• Bloom Color / Period: Blue; April-May
• Wetland Indicator Status: NI (No Indicator) - see flags
• Native Range: Native only to the Ouachita Mountains of central Arkansas and adjacent Oklahoma - a very narrow native range; not native to the Northeast/Mid-Atlantic (see flags)
• Hydrology: Dry-Mesic
• Root Depth: Shallow (Under 12 in.) (primary roots documented to ~30 cm / 11.8 in.)
• Growth Rate: Slow
• Salinity Tolerance: None
• Shade Tolerance: Tolerant - full sun to part shade
• Growth Habit: Clumping/Mounding
• USDA Hardiness Zones: 5-8
• Deer Resistance: Yes (Rarely Damaged)
• Pollinator Value: Supports bees, supports butterflies

Planting Guidance

• Recommended spacing: 24-30 in. on center; plants may take 2-3 years to reach full mature size.