Smooth Aster
Symphyotrichum laeve
Smooth Aster (Symphyotrichum laeve) is a Colorado-native perennial suited to the Colorado Front Range. It matures to about 24 to 36 in tall and 18 to 24 in wide, needs low to medium water, and prefers full sun to partial shade. Smooth blue-green foliage; clouds of lavender daisies in fall; essential late-pollinator nectar.
Colorado nativeOn the CSU listlow to medium water24 to 36 in tall and 18 to 24 in wideXeric / water-wiseLow ignitability: OK 0-30 ft from the house, CSU score 8/10
Photos
- Photo 1: Kathleen Houlahan Chayer, Wikimedia Commons (CC0)
- Photo 2: Shaun Pogacnik, Wikimedia Commons (CC0)
- Photo 3: Judy Gallagher, Wikimedia Commons (CC-BY)
At a glance
Will it survive here?
- Hardiness zones
- USDA 3 to 8
- Water needs
- low to medium water
- Sun
- Best in full sun; tolerates partial shade.
- Soil
- clay, loam, sandy
- Soil pH
- 6.5 to 8.0
- Hail tolerance
- high
- Wind tolerance
- high
- Salt tolerance
- moderate
- Site uses
- Slopes & erosion control
How big, what shape?
- Mature size
- 24 to 36 in tall and 18 to 24 in wide
- Planting spacing
- ~17 to 24 in apart
What it looks like, and when
- Bloom time
- late summer, early fall
- Bloom color
- blue, purple
- Bloom length
- Long (several weeks)
- Foliage
- Deciduous
Who else benefits
- Pollinator value
- high
- Deer
- Not rated
- Colorado native
- Yes
- Native ecoregion
- shortgrass prairie, foothills
Also worth knowing
- Fire rating
- Low ignitability: OK 0-30 ft from the house, CSU score 8/10
Planting & establishment
Deep-water first season to establish, then minimal water needed.
Frequently asked questions
- Is Smooth Aster good for the Colorado Front Range?
- Yes, Smooth Aster is a well-suited perennial for Colorado's Front Range.
- How big does Smooth Aster get?
- It matures to about 24 to 36 in tall and 18 to 24 in wide.
- How far apart do I plant Smooth Aster?
- Space Smooth Aster about 17 in apart for a faster, fuller bed, or up to 24 in apart for a looser planting.
- Is Smooth Aster hardy on the Front Range?
- Smooth Aster is hardy in USDA 3 to 8. The Colorado Front Range spans roughly USDA 4b to 6a, so it is well within range.
- How much water does Smooth Aster need?
- It needs low to medium water once established.
- Is Smooth Aster native to Colorado?
- Yes. It is a Colorado native.
- Is Smooth Aster a good firewise plant near the house?
- Smooth Aster is rated 8 of 10 in CSU Extension Fact Sheet 6.305 (2025), where higher means less ignitable, so it can go within 0 to 5 feet of the house as well as out to 30 feet when kept watered and tidy. This is general guidance based on CSU Extension Fact Sheet 6.305 (2025), not a guarantee that any plant won't burn, a well-irrigated, well-maintained plant is the goal. Follow CSU Extension defensible-space guidance and check with your local fire district before planting in the wildland-urban interface.
- How long does Smooth Aster bloom?
- Smooth Aster blooms for several weeks, a long-season performer on the Front Range. Bloom timing shifts a week or two with elevation and spring weather.
