Alpine aster
Aster alpinus · Asteraceae
A low mountain daisy: violet rays around a golden centre, one flower to a stem, in late spring, months before other asters.
- Size
- 10 in tall, 14 in wide
- Zones
- 4 to 7
- Light
- Full sun
- Flowers
- Mid May to late June
- Pets
- Not checked
- Job in a bed
- Edging
A bed built around alpine aster
The planner designed this bed around alpine aster when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why alpine aster stands where it does.
The plants
- 1 Alpine aster × 8, purple
- 2 Winter heath × 8, pink
- 3 False sunflower 'Summer Sun' × 3, yellow
- 4 Brown-eyed Susan × 3, yellow
- 5 Silver sage × 1, silver leaves
- 6 Eastern bee balm × 3, pink
- 7 Spring starflower × 12, blue
- 8 Star of Persia × 3, purple
Why this plant
- Nothing here is unique to it. Its leaf, flower shape and colour are all on the plan already. Its case rests on where it stands and when it performs.
Why here
- On the front edge. At 10 in it frames the bed without hiding it, and it is in leaf all season. It finishes 45% of the edge.
- 8 plants in 2 runs (5 and 3). Runs of different lengths make the edge a frame, not a ruled line.
Why now
- In flower for six weeks. From mid May to late June.
- Part of the bed's peak. With eastern bee balm and star of Persia in late May: 3 kinds at once. No week has more.
Planned as an English border: 5 of the 6 groups (83%) are drifts, longer along the bed than they are deep. The most in flower at one time is 3 kinds, from late May. Heights step up from about 10 in at the front to 3 ft at the back.
The planner's own design check: 13 Excellent, 4 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where alpine aster goes in a border
At 10 in it belongs at the front of a bed. In the planner's ten height classes it is low (6 to 12 in).
Its job: edging. A low, neat plant used in short runs of three or five along the front to finish the edge (or, in a formal bed, in one even row).
It brings the aster's daisy shape to the front edge in May. Short-lived in heavy, wet soil, so give it grit and full sun, and divide it every few years.
- Rock gardens
- Front edging in sun
- Late-spring daisies
What to plant with alpine aster
Plants recorded as good partners for it, and what each pairing does:
- Sea thrift: in flower together for five weeks, from mid May.
- Rock cress: flowers first, mid April to early May, so the spot is never empty.
- Pasque flower: flowers first, early April to early May, so the spot is never empty.
Questions about alpine aster
Does alpine aster need sun or shade?
Alpine aster grows in full sun (6 or more hours of direct sun a day).
It wants ordinary well-drained soil, on the lean side, with no feeding, and little watering once settled.
What zones does alpine aster grow in?
USDA zones 4 to 7. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does alpine aster flower in my zone?
In zone 5 it flowers mid May to late June. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 4 | Late May to late June |
|---|---|
| Zone 5 | Mid May to late June |
| Zone 6 | Early May to late June |
| Zone 7 | Early May to mid June |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should alpine aster be planted?
12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 14 in (35 cm), so a group knits into one patch.
It grows 10 in (25 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many alpine aster plants do I need?
At 12 in apart, set out in staggered rows:
- 12 to fill 10 square feet (about 1 m²)
- 11 for a single row 10 ft (3 m) long
- 38 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as runs of three or five along the front (or one even row, in a formal bed).
In the bed above, the planner used eight in two groups.
What flowers after alpine aster?
Alpine aster is over by late June. These start as it finishes and carry the same spot on, so it never goes flat:
- Black-eyed Susan: from mid July to mid September, 24 in tall.
- Butterfly weed: from late June to early August, 24 in tall.
- Carpathian bellflower 'Blue Clips': from late June to late August, 8 in tall.
What does alpine aster look like in winter?
Alpine aster dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Aster
- Frikart's aster 'Monch' Aster x frikartii 'Monch'
- Tatarian aster 'Jindai' Aster tataricus 'Jindai'
In these guides
Every fact on record
- Type
- Perennial
- Size
- 10 in (25 cm) tall, 14 in (35 cm) wide
- Plant
- 12 in (30 cm) apart
- Height class
- Low (6 to 12 in)
- Place in the bed
- Front
- Flowers
- Mid May to late June; daisies; purple, lavender, pink, white
- Leaves
- Medium texture, herbaceous; green
- Shape
- Mounding, clumping
- Hardy in
- USDA zones 4 to 7
- Light
- Full sun
- Soil
- Lean, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Asteraceae
Checked against VASCAN (plants of Canada). Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.