China aster

China aster: how do you recognise it?

Habit

Upright, branching annual 30–60 cm tall and about 30 cm wide, depending on the variety.

Leaves

Oval to diamond-shaped, coarsely toothed, slightly hairy and mid-green.

Flower

Flower heads 5–10 cm across, single, semi-double or fully double, on long stems.

Colour

White, cream, pink, red, purple and violet-blue; single flowers have a yellow centre.

Roots

A fine, fairly shallow root system that is susceptible to soil-borne fungi.

Flowering: July–October · Sowing: March–May · Plants: May–June

Why grow it?

• Flowers from July into October, when many other annuals are past their best.
• An excellent cut flower with long stems that lasts well in the vase.
• Single forms attract bees and butterflies; double forms much less so.
• A wide choice of flower forms and colours, including violet-blue.
• Dwarf varieties look good in pots or as an edging along a path.

China aster: where does it grow best?

• Full sun; in shade it flowers less and the stems flop.
• Free-draining, humus-rich soil: sand, loam or clay, neutral to chalky.
• Moderately moist: do not let it dry out, but avoid waterlogging.
• Choose a different spot every year, ideally where no China asters have grown in recent years, because of aster wilt.
• Plant 25–30 cm apart.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Normal

Size

0.6 m tall, 0.3 m wide

Hardiness

Frost tender: plant out after the last frost (mid-May)

Goes well with

• Zinnia: Same sowing time and same sunny spot; lovely together in the cutting garden.
• Snapdragon: Upright spikes next to the round aster flowers.
• Dahlia: Flowers at the same time, in late summer and autumn.
• Purpletop vervain: Airy purple flower clusters above them, also a magnet for butterflies.

China aster: when and how to plant it?

Plant in May–June.

1. Sow indoors in March–April in a tray at room temperature and prick out the seedlings into small pots.
2. In May, harden off the young plants for a week: outside during the day and indoors at night.
3. Plant out after mid-May, when there is no more risk of night frost, 25–30 cm apart.
4. Plant at the same depth as in the pot and firm the soil well.
5. Water straight away and keep the soil moist for the first few weeks.
6. You can also sow directly outdoors in May; flowering then starts a little later.

Care

Water

In dry weather, water at the base, preferably in the morning: wet leaves encourage fungal disease.

Feeding

Some compost at planting time is enough. Too much nitrogen gives soft, disease-prone growth.

Support

Support tall varieties with a net or canes, especially in a windy garden.

Spent flowers

Remove them regularly to extend flowering.

Crop rotation

Grow China asters in a different spot every year and only return to the same place after several years.

Tip: Never grow China asters in the same spot two years running: aster wilt stays in the soil. Water at the base in the morning, so the leaves stay dry.

China aster: when to prune it?

When: China asters need no pruning. From July to October, cut flowers for the vase and remove faded blooms.

How:

• For the vase, cut when the flowers are almost fully open, with a long stem.
• Cut faded flowers off just above a side shoot.
• Clear the plants away in autumn after the first frost; diseased plants should not go on the compost heap.

Pruning calendar and basic rules

Propagation

Seed

Only from seed. Sow indoors in March–April or outdoors in May. You can collect seed from single-flowered plants in autumn, but seed from double varieties does not always come true.

China aster: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Not hardy: the plant dies with the first frost.
• Pull the plants up after the first frost and put diseased plants in the household waste, not on the compost heap.
• Store your own seed dry and cool until spring.

Diseases and pests

• Aster wilt: Plants suddenly wilt and the base of the stem turns brown or black. It is a soil-borne fungus that stays in the ground for years: remove affected plants and choose a different spot every year.
• Aster yellows: Green, distorted flowers and yellow leaves, caused by a disease spread by leafhoppers. Remove affected plants straight away.
• Aphids: On young shoots and under the leaves. Spray them off with water; ladybirds help.
• Slugs: They eat young plants after planting out. Check in the evening and protect the young plants.

Through the year

• March: Sow indoors at room temperature.
• April: Sow indoors. Prick out seedlings into small pots.
• May: Harden off. Plant out after mid-May, or sow outdoors.
• June: Plant out the last plants. Support tall varieties. Water in dry spells.
• July: First flowers. Cut flowers for the vase.
• August: Flowering. Remove faded flowers, water at the base.
• September: Full flower. Collect seed from single-flowered plants.
• October: Last flowers. Clear the plants away after the first frost.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The name Callistephus comes from Greek and means ‘most beautiful crown’.
• It is not a true aster: it has a genus of its own, in which it is the only species.
• It reached Europe from China in the eighteenth century, and growers soon selected countless forms.