Symphyotrichum laeve (smooth blue aster, smooth aster, smooth-leaved aster, glaucous Michaelmas-daisy or glaucous aster) is a flowering plant native to Canada and the United States.

Smooth aster is 20 to 70 cm (8 to 28 inches) tall. The flower heads are arranged in clusters (panicles), pale to dark blue or purple petals. The whole flowerhead measures 1⁄2 to 1 inch (1.3 to 2.5 cm) across.

Symphyotrichum laeve is found throughout North America, in gardens, and naturally occurring in fields, open woods and along roadsides. It grows in rocky or dry soil in full sun.

Symphyotrichum laeve blooms in late summer and early fall. It is pollinated by many native bees and attracts butterflies. It is a larval host for the pearly crescent butterfly (Phyciodes tharos).

Type: Hardy perennial

Height: 24", 60 cm

Location: Sun or part sun

Hardiness zones: 3-9

Seeds per pack: 25

Note: Ornamental use only. May be poisonous.

Germination: Start these seeds right away to preserve viability, no matter the time of year. Sow the seeds just under the surface of a sterile seed-start mix, and water in. Then cover them with plastic and place in a fridge for 5-6 weeks. Be sure they stay moist. After the cold stratification period they are then brought back to room temperature for them to germinate. Germination is generally within 60 days after the warming period, though they could take a few months. If possible, the best location for sowing in March, April and May, is in cold frame or a cold greenhouse where they will receive the cold period and fluctuating temperatures naturally.