Spring planting doesn’t start when the air feels warm, It...Read More
Smooth Blue Aster is a graceful perennial that showcases clusters of sky-blue, daisy-like flowers from late summer into fall. Loved by pollinators, this aster attracts bees, butterflies, and other beneficial insects, making it a wonderful addition to any wildlife-friendly garden. It thrives in full sun and well-drained soils, handling both drought and a range of soil types with ease. Growing up to 3 feet tall, its airy, arching stems add height and texture to borders, prairies, or meadows. Smooth Blue Aster is an excellent choice if you are looking for a low-maintenance, late-season bloomer to add to your flower garden.
NAME: Aster (Symphyotrichum laeve)
VARIETY: Smooth Blue
DAYS TO MATURITY: 110+ days
POLLINATION: Open Pollinated
TYPE: Perennial
HARDINESS ZONE: Zones 3 – 8
SUNLIGHT: Full Sun – Partial Sun
SOIL: Average, well-draining soil with a pH 5.8 – 7.5
PLANT HEIGHT: 24 – 48 inches
SPACING: 14 – 24 inches apart
TEMP: 40 – 90ºF
These seeds do not require stratification. Smooth Blue Aster seeds germinate well without any special treatment. Simply sow directly in soil or in trays indoors.
To learn more about Stratification, click here!
Start seeds indoors 6-8 weeks before the last expected frost.
Sow seeds 1/8 inch deep in seed trays filled with moist potting soil. Lightly press down to ensure seed contact but avoid covering them too deeply.
Maintain soil temperatures between 65-70°F. Germination should occur within 10-15 days.
Thin seedlings to one per cell as they emerge.
Gradually expose seedlings to outdoor conditions for a week before transplanting.
When transplanting, space plants about 14-24 inches apart in well-draining soil.
Direct sow outdoors in the spring, after the last frost, or in the fall to allow for natural cold conditioning.
Choose a location with full sun to partial shade and well-drained soil.
Lightly press seeds into the soil surface but do not cover them as they need light to germinate.
Keep the soil moist until germination occurs, usually within 10-16 days.
Once seedlings emerge, thin them to 12-18 inches apart.
Light: Smooth Blue Asters prefer full sun, though they tolerate partial shade. Plants in full sun generally produce more blooms.
Soil: They thrive in various soil types, including sandy loam and clay, as long as the soil drains well.
Water: Regular watering is essential while plants establish, but Smooth Blue Asters are drought-tolerant once mature. Avoid overly wet soil.
Fertilization: Not necessary, but a light application of compost or balanced fertilizer in early spring can promote growth.
Pruning: To encourage bushier growth and prevent flopping, you can trim back the top third of the plant in late spring. Deadheading spent flowers extends the blooming period and reduces self-seeding.
Decorative Use: Cut Smooth Blue Aster flowers when they are fully open, typically from late summer through early fall.
Smooth Blue Asters add beauty to fresh and dried arrangements, with their delicate purple blooms and vibrant yellow centers. Regular cutting also encourages the plant to produce additional flowers throughout the season.
