Smooth Aster vs Nodding Onion - TreeTime.ca

Smooth Aster vs Nodding Onion

Symphyotrichum laeve

Allium cernuum

NOT AVAILABLE THIS SEASON - MIGHT RETURN

NOT AVAILABLE THIS SEASON - MIGHT RETURN

Smooth Aster
Nodding Onion

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. As a perennial, it dies back to the crown each winter, it will regrow from the base in the spring. Avoid disturbing the crown during late winter to ensure healthy growth the following season.

Nodding Onion is a native perennial wildflower known for its nodding clusters of flowers that range in color from white to pink to purple. The lightly scented blooms provide pollen and nectar for pollinators, especially bees, which can collect while hanging upside down, a capability most other insects lack.

The narrow, grass-like leaves of the Nodding Onion can be used as a seasoning in cooked dishes, though bulbs and raw leaves should not be eaten in large quantities. All parts of the plant have an onion-like aroma when bruised, which helps deter deer and rabbits. They can self-seed readily, so removing spent blooms helps manage their spread. Tolerant of a range of soils, including alkaline, it is well-suited for a variety of plantings, including pollinator gardens and naturalization projects.

Smooth Aster Quick Facts

Nodding Onion Quick Facts

Zone: 3a
Zone: 3a
Height: 0.9 m (3 ft)
Height: 0.3 m (1.0 ft)
Spread: 0.6 m (2.0 ft)
Spread: 0.2 m (0.5 ft)
Light: partial shade, full sun
Light: partial shade, full sun
Moisture: dry, normal
Moisture: dry, normal
Growth rate: very fast
Growth rate: fast
Life span: short
Life span: short
Growth form: upright to spreading, clump-forming
Spreading: seeds - high
Suckering: none
Maintenance: medium


Toxicity: raw leaves and bulbs can be midly toxic
Foliage: smells of onion when crushed, edible
Flowers: purplish-blue; daisy-like
Flowers: white, pink, or purple nodding clusters
Bloom time: late summer to early fall
Bloom time: late spring to summer
Hybrid: no
Hybrid: no
Catkins: no
Catkins: no


Native to: AB, BC, SK, MB, ON
Native to: AB, BC, SK, ON
Other Names: glaucous aster, smooth blue aster
Other Names: ladys leek, nodding wild onion