Smooth Aster is a perennial grown for its blue blooms, which open in summer and return year after year. It's hardy across USDA zones 3 through 8, shrugs off deer and shrugs off dry spells. Its summer flowers are a real draw for honeybees, native bees, butterflies, and moths.
Zones
3-8
pH Range
5.5-7.5
Sun
Full Sun
Days to Maturity
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What Smooth Aster is
Smooth Aster grows as a perennial and reaches around three feet at maturity. It blooms blue in summer. It's also deer-resistant.
How to grow Smooth Aster
Smooth Aster grows in USDA zones 3 through 8. Smooth Aster does best in full sun — at least 6 hours of direct sun a day — and soil from pH 5.5 to 7.5, on well-drained ground.
USDA Zones
3-8
USDA PHZM 2023
Soil pH
5.5 - 7.5
USDA PLANTS Database
Sun
Full Sun
plant_species_v5.csv
Drainage
well (dry spells)
plant_species_v5.csv
Mature Height
3 ft
plant_species_v5.csv
Start the season right
Plant smooth aster in full sun with at least 6 hours of direct sun, once the soil has warmed and frost risk has passed.
Match the soil
Smooth Aster prefers pH 5.5 to 7.5 (USDA PLANTS Database). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band.
Water steadily
Keep the root zone evenly moist through establishment. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at its peak
Cut smooth aster blooms in the cool of the morning, just as they open, for the longest display.
Good to know
Good news for pet owners — smooth aster isn't known to be toxic to dogs or cats. (Source: ASPCA.)
Smooth Aster is a standout pollinator plant — high value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)
Where Smooth Aster thrives
Smooth Aster is hardy across USDA zones 3 through 8. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
Zones 3–8·Where Smooth Aster growsOpen map →
On USDA hardiness-zone overlap, Smooth Aster can grow in these states:
See if Smooth Aster will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether smooth aster actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Frequently Asked Questions
Can I grow Smooth Aster in my zone?
Smooth Aster grows in USDA hardiness zones 3 through 8 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Smooth Aster?
Most growers plant smooth aster after the last spring frost, once the soil has warmed. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Smooth Aster need?
Smooth Aster needs full sun — a spot that catches at least 6 hours of direct summer sun a day. In more shade it still grows, but usually gives a smaller, later crop. The catch is that a yard rarely gets even light everywhere — a fence, the house, or one tall tree can quietly take those hours. A Growable Ground report reads the real sun-hours across your land, canopy and buildings included, so you can pick the brightest bed before you plant.
What soil does Smooth Aster need?
Smooth Aster prefers soil pH 5.5 to 7.5, on well-drained ground (USDA PLANTS Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Smooth Aster attract pollinators?
Yes — smooth aster's flowers are a strong nectar and pollen source for honeybees, native bees, butterflies, and moths (Xerces Society, Pollinator Partnership).
Is Smooth Aster safe for pets?
Smooth Aster is not known to be toxic to dogs or cats based on available data (ASPCA). Always supervise pets around new plantings.