October Skies aster

Sun

Full sun gives the best flowering and strongest growth; light shade is tolerated but can produce looser stems.

Water

Water regularly during establishment. Once established, water during prolonged drought; avoid persistently wet soil.

Soil

Well-drained sandy, gravelly or loamy soil, including relatively poor soil. Tolerates clay if drainage is good; avoid wet winter ground.

Height

1.5-2 ft (0.45-0.6 m)

Spread

2-3 ft (0.6-0.9 m)

Flowers

Late summer to autumn, usually September-October in the Northern Hemisphere; lavender-blue daisies with yellow centres that darken with age.

Foliage

Small, narrow-oblong green leaves with a noticeable aromatic scent when crushed; leafy, branching stems die back in winter.

Growth

Moderate; forms a broad clump and gradually spreads by short rhizomes.

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Cold hardy
• Wildlife
• Low allergen
• Fragrant

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.2 ft (0.37 m)

3. After 2 years

   1.5 ft (0.45 m)

4. After 3 years

   1.7 ft (0.53 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US

Growth rate

Moderate

• Water deeply through the first growing season, allowing the soil surface to dry between waterings.
• Avoid routine heavy feeding; rich soil and excess nitrogen encourage loose, floppy growth.
• Apply a light compost mulch in spring if needed, keeping it away from the crown.
• Divide congested clumps in spring every three to four years, or when flowering declines.
• Give plants room for air circulation; staking is rarely needed in full sun.

Pruning. Cut dead stems to just above ground level in late winter or early spring. If a shorter, denser mound is wanted, trim stems back by about one-third in late spring; avoid late-summer cutting, which removes developing flowers.

Late winter

Cut down last year's stems before new shoots emerge.

Early spring

Plant or divide clumps in well-drained soil, allowing for their mature spread.

Late spring

Optionally shorten stems by one-third to encourage a denser mound.

Summer

Water new plants during dry spells and check that neighbouring plants are not crowding them.

Autumn

Enjoy the flowers; leave some seedheads standing for wildlife, or remove them to limit seedlings.

• Plant along the front or middle of a sunny border for a broad mound of autumn colour.
• Repeat in drifts among little bluestem and other fine-textured grasses for a prairie-style planting.
• Combine with goldenrods and black-eyed Susans for contrasting blue and yellow flowers.
• Use in a well-drained gravel garden where its late flowers extend the season after many drought-tolerant perennials finish.

Garden styles it suits: Cottage garden, Native meadow, New perennial (prairie), Pollinator garden, Dry gravel garden and Autumn colour.

Plant it with: Little bluestem, Prairie dropseed, Butterfly weed, Black-eyed Susan, Showy goldenrod and Purple coneflower.

Wildlife: The late flowers provide nectar and pollen for bees, butterflies and other insects. Retained seedheads may feed small birds, while standing stems offer shelter for overwintering invertebrates.

• Powdery mildew can occur, especially in crowded planting: provide full sun and airflow, and remove badly affected foliage.
• Root or crown rot can develop in waterlogged soil: improve drainage or move the plant to a raised, freer-draining position.
• Lace bugs may cause pale stippling on leaves: check leaf undersides and use insecticidal soap on affected foliage if damage is substantial, avoiding open flowers and visiting insects.
• Floppy stems or sparse flowering usually indicate too much shade or rich feeding: move to stronger sun, stop high-nitrogen fertiliser and trim lightly in late spring if needed.

Not known to be toxic to cats, dogs, horses or people; no part is recognised as a significant poisoning hazard. It is an ornamental plant, not a recommended food plant.

• Raydon's Favorite aromatic aster (Symphyotrichum oblongifolium 'Raydon's Favorite')

  Usually forms a taller mound, about 2-3 ft (0.6-0.9 m), whereas 'October Skies' is typically shorter and broader. Their flowers and aromatic foliage are very similar, so a reliable label is the best confirmation.

• New England aster (Symphyotrichum novae-angliae)

  Usually much taller, with hairy stems and leaves whose bases clasp the stems. October Skies has a low, spreading habit and small aromatic leaves.

• Smooth aster (Symphyotrichum laeve)

  Has smooth, often blue-green leaves, with upper leaves clasping the stems. October Skies has smaller, rougher-textured green leaves that release an aromatic scent when crushed.

The species name oblongifolium refers to its oblong leaves, while 'October Skies' evokes the blue flowers and their autumn flowering season.

Propagation. Divide in spring or take softwood cuttings from young shoots in late spring. These methods preserve the cultivar; seedlings may differ from the parent. Remove unwanted spreading shoots at the edge of the clump.

Accepted botanical name

Symphyotrichum oblongifolium

In the US and Canada

Native in the lower 48 states.

Native range

Alabama, Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Mexico Northeast, Minnesota and Mississippi.

Measured

Average height 43 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.