Calico aster

Calico aster: how do you recognise it?

Habit

Bushy, dense clump 0.6–1 m tall and about 50 cm wide, with side branches held out horizontally.

Foliage

Lance-shaped, 5–10 cm long, green; dark and purple-tinged in ‘Lady in Black’.

Flower

Countless small flower heads about 1 cm across with white ray florets, in September and October.

Colour

White, with a centre that changes from yellow to pink or purple-red.

Roots

Short, branching root system that slowly widens the clump; easy to divide.

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

Why grow it?

• Flowers in September and October in a cloud of small white stars with pink centres.
• Tolerates sun and light shade, which is not a given with asters.
• Stays firm without support and shows off attractive horizontal branches.
• Bees and butterflies find nectar here late in the season.
• The dark foliage of ‘Lady in Black’ adds colour to the border from summer on.

Calico aster: where does it grow best?

• Sun to partial shade; in full sun it flowers most and stays compact.
• Ordinary garden soil: sand, loam or clay, acid to chalky. A moderately fertile soil is ideal.
• Reasonably moist; do not let it dry out in summer, especially in full sun.
• Allow about 50 cm between plants.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.8 m tall, 0.5 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Japanese anemone: Flowers at the same time and shares the partial shade.
• Stonecrop: Pink flower heads in the same autumn period.
• Feather reed grass: An upright ornamental grass that makes the fine branches stand out.
• Lady’s mantle: A fresh, yellow-green edge at the foot of the clump.

Calico 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 not frozen.
2. Dig a hole twice as wide as the root ball and mix in a little compost.
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 50 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 leaf mould around the plant.

Care

Water

In the first year water weekly in dry weather. After that only in long dry spells, at the base.

Feeding

A thin layer of compost in spring. Over-rich soil gives soft growth.

Support

Usually not needed: the branches stay firm without a plant support.

Spent flowers

Leave them for winter structure. If you do not want self-sown seedlings, cut the sprays off before they set seed.

Dividing

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

Tip: Use it in light shade too, where most asters give up. In autumn, cut off the sprays if you do not want self-sown seedlings.

Calico 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 or shears 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 ‘Lady in Black’ do not always come true from seed.

Calico 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.
• Leave the spent stems standing until March: they decorate the winter garden and shelter insects.
• In a pot: put it against a wall and wrap the pot in hessian in severe frost.

Diseases and pests

• Powdery mildew: White powder on the leaves, mostly in dry weather and when plants are too close together. Give space, water at the base and cut off affected leaves.
• Slugs: They eat young shoots in spring. Collect them in the evening and protect young plants.
• Aphids: On young shoots in summer. Spray off with water; ladybirds help.
• Self-sown seedlings: The plant can self-seed. Pull unwanted seedlings in spring or cut the sprays off before they set seed.

Through the year

• March: Cut back to 10 cm. Add compost. 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. Water in long dry spells.
• August: Buds form.
• September: Flowering begins. Planting is still possible.
• October: Full flower. Planting or dividing is still possible.
• November: Leave the stems as winter decoration and for insects.
• December: Dormant.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• ‘Calico’ refers to the changing centres, which go from yellow to pink or purple-red.
• The name lateriflorum means ‘with side flowers’ and refers to the flowers along the side branches.
• This North American aster used to be placed in the genus Aster.