Aromatic aster

Aromatic aster: how do you recognise it?

Habit

Compact, rounded clump 40–60 cm tall and about 60 cm wide, with many side branches.

Foliage

Oblong to lance-shaped, grey-green and rough-hairy; the name ‘aromatic’ refers to the scent when rubbed.

Flower

Countless daisy-like flowers 2–3 cm across, violet-blue with a yellow centre, from September to November.

Roots

Short rhizomes that slowly widen the clump; easy to divide.

Flowering: September–November · Plants: March–May and September–October · Pruning: March

Why grow it?

• Flowers from September into November, when almost all other perennials have finished.
• Tolerates drought and a sunny, lean spot, where many asters struggle.
• Stays free of powdery mildew, a common problem with autumn asters.
• Bees and butterflies find nectar here late into the season.
• A compact, rounded clump that holds its shape without support; good for cutting too.

Aromatic aster: where does it grow best?

• Full sun: the clump stays compact and flowers best.
• Well-drained soil: sand or loam, acid to chalky. A lean to moderately fertile soil is ideal.
• Dry to reasonably moist; it tolerates drought well. Wet soil in winter is its greatest enemy.
• Allow about 60 cm between plants.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Dry

Size

0.5 m tall, 0.6 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Stonecrop: Pink to red flower heads in the same autumn period, in the same dry, sunny spot.
• Fountain grass: A light ornamental grass that flowers in autumn in the same sun.
• Blue fescue: A low, blue-grey grass that frames the flowers at the front.
• Coneflower: Drought-tolerant and still flowering in late summer.

Aromatic aster: when and how to plant it?

Plant in March–May and September–October.

1. Plant in March–May or in September–October, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball; on heavy soil, mix in sand or fine grit.
3. Set the plant at the same depth as in its pot, with the top of the root ball level with the soil.
4. Leave 60 cm between plants.
5. Water thoroughly straight away and keep the soil lightly moist in the first season.
6. Spread a thin layer of compost or grit around the plant, keeping the crown clear.

Care

Water

In the first year water weekly in dry weather. After that it manages alone; water only in a long drought.

Feeding

Usually not needed. Over-rich soil gives long, floppy stems and fewer flowers.

Support

Not needed in a sunny, lean spot.

Spent flowers

Leave them: the stems and seeds give structure in winter and shelter insects.

Dividing

Dividing the clump every 3–4 years in spring keeps the plant vigorous and flowering well.

Tip: Plant it in a sunny, lean spot and do not feed it: it stays compact and sturdy. Leave the stems standing in winter for insects.

Aromatic aster: when to prune it?

Pruning months: March.

When: In March, before the new shoots come through.

How:

• Cut all the old stems back to about 10 cm above the ground.
• Use sharp secateurs and clear away the clippings.
• During the season, remove dead or broken stems at the base.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April: cut the clump with a spade into pieces with roots and shoots and replant at once.

Cuttings

In April–May: take 8–10 cm cuttings from the young shoots at the base and root them in moist cutting compost. They root in a few weeks.

Seed

Sow outdoors in spring in a seedbed. Cultivars such as ‘October Skies’ do not always come true from seed.

Aromatic aster: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, down to about −30 °C: no protection is needed in Belgium.
• The danger is wet soil, not frost: make sure drainage is good.
• Leave the spent stems standing until March: they decorate the winter garden and shelter insects.

Diseases and pests

• Root rot: After a wet winter the plant does not reappear or the leaves turn yellow. Plant in free-draining soil, on a slight mound, with sand in the hole.
• Soft growth: On over-rich soil or with too little light. Plant in full sun and do not feed.
• Slugs: They eat young shoots in spring. Collect them in the evening and protect young plants.
• Powdery mildew: Rare. If white powder appears on the leaves: give space, water at the base and cut off affected leaves.

Through the year

• March: Cut back to 10 cm. Plant or divide.
• April: Plant or divide. Take cuttings from young shoots.
• May: Plant. Watch for slugs.
• June: In the first year, water in dry weather.
• July: Growth. In the first year, water in dry weather.
• August: Buds form.
• September: Flowering begins. Planting is still possible.
• October: Full flower. Planting or dividing is still possible.
• November: Last flowers. Leave the stems standing.
• December: Dormant. The dry stems decorate the garden.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• In the wild this aster grows on dry prairies and rocky slopes.
• The name aster comes from the Greek for ‘star’.
• Asters belong to the daisy family, like the lawn daisy and the sunflower.