Amsonia tabernaemontana is a clump-forming North American native perennial in the dogbane family (Apocynaceae). It produces clusters of small, star-shaped, pale steel-blue flowers in mid- to late spring, then holds clean, willow-like foliage through the growing season. In fall, that foliage turns a consistent, clear yellow-gold — one of the most reliable fall-color performances of any herbaceous perennial in the border.
Established clumps are long-lived, drought-tolerant, and virtually maintenance-free. Full sun produces the most compact, floriferous plants and the most vivid fall color; part shade causes stems to stretch and flop. Shearing by one-third right after bloom keeps the habit tight and mounded. The milky sap is mildly toxic and the plant is largely ignored by deer and rabbits. It rarely needs division and resents excessive disturbance once settled.
As a native species, eastern bluestar supports native bees and small pollinators during its spring bloom window. Its dense root system stabilizes stream banks and low-lying areas, and it naturalizes well in rain gardens and woodland edges.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.
Aphids
Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.