Smooth Aster vs Showy Milkweed - TreeTime.ca

Smooth Aster vs Showy Milkweed

Symphyotrichum laeve

Asclepias speciosa

COMING SOON

(new stock expected: fall of 2026)

NOT AVAILABLE THIS SEASON - MIGHT RETURN

Smooth Aster
Showy Milkweed

Smooth Aster is a native perennial wildflower known for its violet-blue, daisy-like flowers. They bloom later in the season, from late summer to early fall. The flowers attract a variety of pollinators, including bees, butterflies, and other beneficial insects. It also serves as a host plant for the Silvery Checkerspot (Chlosyne nycteis) and Pearl Crescent (Phyciodes tharos) butterflies, further enhancing its ecological value. This easy-to-grow wildflower is well suited for native wildflower gardens, pollinator gardens, and naturalization projects.

The Smooth Aster’s non-aggressive root system allows it to spread slowly, and it is more likely to reproduce by seed, which can be controlled through deadheading.

Showy Milkweed is a native perennial wildflower known for its fragrant clusters of pink to purple, star-shaped flowers. It is an essential plant for Monarch butterflies, acting as a critical host plant for caterpillars and a nectar source for adults. Blooming from early to mid-summer, these flowers also supply nectar to many other pollinators, including bees, butterflies, moths, and hummingbirds.

Ideal for butterfly conservation, pollinator gardens, and naturalization projects, Showy Milkweed thrives in a wide range of soils, including dry and rocky ground. While it spreads via underground rhizomes to form colonies, it is much less aggressive than Common Milkweed (Asclepias syriaca).

Note: All parts of the plant contain toxic cardiac glycosides, especially the milky sap. Do not ingest any part of the plant and prevent sap from contacting skin or eyes. Toxic to humans, pets, and livestock.

Smooth Aster Quick Facts

Showy Milkweed Quick Facts

Zone: 3a
Zone: 3a
Height: 0.9 m (3 ft)
Height: 0.9 m (3 ft)
Spread: 0.6 m (2.0 ft)
Spread: 0.5 m (1.5 ft)
Light: partial shade, full sun
Light: full sun
Moisture: dry, normal
Moisture: dry, normal
Growth rate: very fast
Growth rate: fast
Life span: short
Life span: short
Growth form: upright, clump forming
Spreading: rhizomes - high, seeds - high
Suckering: none
Maintenance: medium


Toxicity: toxic to pets, livestock, and humans if ingested, can cause skin and eye irritation.
Flowers: purplish-blue; daisy-like
Flowers: purplish-pink clusters
Bloom time: late summer to early fall
Bloom time: early to mid summer
Hybrid: no
Hybrid: no
Catkins: no
Catkins: no


Native to: AB, BC, SK, MB, ON
Native to: AB, BC, MB, YT
Other Names: glaucous aster, smooth blue aster