Callistephus chinensis [kal-LISS-steff-us, chi-NEN-sis] is a species of annuals with bright showy flowers.
Typically grown from seed, these plants may reach up to 2’ feet, producing thin stems topped with masses of flowers toward the end of summer.
The plant is native to China and commonly called China aster or annual aster as it belongs to the Asteraceae family.
Perfect for large tubs or to offset darker plants, amateur gardeners throughout the world cultivate the annual China aster.
While most people grow it as an ornamental plant, it’s commonly used for the art of flower arranging in Japan.
Callistephus Chinensis Care
Size and Growth
The China aster ranges in height between 8” – 36” inches.
It produces branching stems and many side shoots, resulting in bushy growth.
Most varieties have leaves with jagged or toothed edges which sometimes overlap.
Flowering and Fragrance
The flowers are the main reason to cultivate China aster.
It blooms late in the summer, producing a cluster of flowers with many delicate little petals.
The colors range from purple or violet to bright red or pink.
The flowers don’t produce a scent, but they tend to last for quite a few weeks.
Light and Temperature
Callistephus chinensis can survive freezing temperatures during the winter.
It’s suited for outdoor cultivation in USDA hardiness zones 2 to 10, covering most of the United States.
The plant also grows well in a variety of lighting conditions.
It can thrive under normal light, direct sunlight, or partial shade.
For optimal growth, plant the annual under the cover a tall tree.
The leaves of the tree provide a shifting pattern of sunlight throughout the day.
Watering and Feeding
Keep an eye on the plants and the weather.
During dry spells, water the plant regularly.
Add liquid fertilizer to the water every second or third time during the warmer months.
Soil and Transplanting
Use light soil with a neutral pH level.
Most people grow these plants from seed using starter trays indoors at the end of spring.
Transplant the young plants outdoors in early June to encourage fuller blooms.
After moving the plants outdoors, don’t transplant again.
These plants are relatively hardy, but the root system may not always survive the stress of transplanting.
These plants rarely need grooming.
If the side shoots begin to spread beyond the intended growing area, remove them and consider planting in a different spot.
How to Propagate Callistephus Chinensis
Propagate from seeds, either using store-bought packets or seeds harvested from the plant.
NOTE: Plants grown from harvested seeds may not produce even blooms.
Some plants may have fewer flowers, resulting in uneven quality.
To try obtaining seeds from the plant, wait until the end of September.
The flowers should be toward the end of their growth cycle.
Pick the most attractive flower buds and collect the seeds.
Store them in an envelope in a dry spot.
When winter comes, keep the seeds in a cool room with limited humidity, such as a well-ventilated basement.
Sow the first set of seeds in starter trays at the end of spring.
In June, take the plants outdoors.
This is also a good time to consider planting a second row for later bloom.
Sow the second set directly outdoors in the garden.
The first bloom should arrive toward the end of summer while the second row of plants may bloom at the start of fall.
This gives the garden more color for a longer period.
Callistephus Chinensis Pests and Diseases
These plants are not toxic or considered invasive.
They are also incredibly hardy and resilient but may occasionally suffer from disease or pests.
When grown in bright, dry locations, the China aster may develop mildew.
It appears as a white powder on the stems and leaves, weakening the entire plant.
To prevent mildew, occasionally mist the plant in the morning.
NOTE: The plant typically only needs misting in dry environments when placed under direct sunlight.
If the plant gets too much moisture, it may develop stem rot.
This is more common when dealing with cool air and high humidity.
Rot causes the plant to stop growing.
The leaves, stems, and flowers may start to wither and die.
When growth stops, top off the soil with sand and stop watering.
The sand should help protect against additional moisture.
Wait until growth starts before resuming watering.
Pests rarely attack the plant, but if aphids appear, spray them with an insecticide or spray them away with water from the garden hose.
For severe attacks, spray at least two weeks before cutting flowers.
Suggested Callistephus Chinensis Uses
The bright China aster works well in front of taller, darker plants, adding more color to your garden.
It’s also a suitable tub plant but should remain in its container after the first planting.