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© Martin Purdy, some rights reserved (CC-BY) · iNaturalist
Overview
Symphyotrichum spathulatum is a herbaceous perennial reaching 6-30 inches (15-75 cm) tall and 1-2 feet (30-60 cm) wide, forming clumps from short rhizomes. Stems are slender, mostly hairless, and often unbranched in the lower portion. Lower leaves are spatulate (spoon-shaped) and 1-3 inches (2.5-7.5 cm) long, on winged petioles; upper stem leaves are smaller and lance-shaped, with smooth or sparsely toothed margins. Composite flower heads 0.75-1.5 inches (2-4 cm) across appear in loose, flat-topped to rounded clusters from July through September, with peak bloom in August. Each head has 15-30 pale lavender to blue-violet ray florets surrounding a yellow disc that ages to reddish-purple. Each flower head lasts 7-14 days; total bloom on a single plant extends 4-8 weeks. Achenes mature September through October. Foliage dies back to the rhizome after fall frosts in zones 4-7. Spreads slowly by short rhizomes, expanding 2-4 inches (5-10 cm) per year. Lifespan 5-12 years. Several varieties are recognized across the range, differing in stature and leaf size.
Native Range
Native to mountain meadows, streamside terraces, and moist openings in the mountains of western North America from southern British Columbia south through the Cascades, Sierra Nevada, and Rocky Mountains to northern New Mexico. Found at elevations of 4,000-11,000 feet (1,200-3,350 m), in seasonally moist sites that dry by late summer.Suggested Uses
Used in mountain meadow restorations, subalpine garden plantings, and late-season pollinator borders in interior West gardens. Spaced 12-18 inches (30-45 cm) apart in groupings of 5-9 plants. Garden longevity is greatest in cool maritime and montane climates; lowland sites in zones 7 and warmer often produce poor flowering and shortened lifespan.How to Identify
Appearance
Size & Dimensions
Height6" - 2'6"
Width/Spread1' - 2'
Reaches mature size in approximately 3 years
Bloom Information
Flowers from July through September across the range, with peak bloom in August at most sites. High-elevation populations (above 8,000 feet / 2,400 m) bloom from late July through mid-September. Each flower head lasts 7-14 days; total bloom on a single plant extends 4-8 weeks.Detailed Descriptions
Flower Description
pale lavender to blue-violet with yellow centerFoliage Description
medium greenGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant container-grown stock or sow seed in fall in moist, well-drained loamy or rocky soils with full sun to light shade. Water during the first growing season; established plants tolerate summer drought once dormant in late summer. Cool root zones support growth; the species struggles in hot lowland gardens (below 2,000 feet / 600 m), where leaf scorch and crown decline are common. Powdery mildew may affect lower foliage in humid conditions but causes only cosmetic damage. Crowns persist 5-7 years and benefit from division every 4-5 years in early spring.Pruning
Cut spent flowering stems to the basal foliage in late fall after seed has dispersed, or leave through winter for songbird forage. Pinch growing tips at 6-8 inches (15-20 cm) tall in early summer to encourage branching in fertile soils. Divide every 4-5 years in early spring.Pruning Schedule
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