Callistephus

( kal - LISS - tef - us )

At-A-Glance Information

Also called China Aster, this monotypic genus of flowering annuals grows best in USDA hardiness zones 2-11 or Sunset growing zones 1-24 (to find your zone, click here: Zone Map) and needs full sun and regular water to perform well. Summertime flowers will attract butterflies and other pollinators to the garden. Plants reach 8-36 inches tall and 10-18 inches wide. Some varieties are branching, others are not; those without a branching habit are best for cut flowers. They come in many different flower forms, and available colors include white, pastel pink, rose-pink, lavender, lavender-blue, violet, purple, crimson, wine and scarlet. Grow China Asters in mixed beds and borders or in containers. The genus includes one species, Callistephus chinensis, and is a member of the plant family Asteraceae.

Callistephus Varietals and Cultivars

These cultivars have been bred for their flower composition, color, stem height, or resistance to pests and diseases.

'Blue and White'
With bicolored violet flowers that have creamy white centers.

'Bonita Shell Pink'
To 3 feet tall, with light pink flowers that have yellow centers.

'Bonita White'
With pure white flowers on a plant that reaches 3 feet tall.

'Crego Giant'
A mix with very large purple, pink, white, and red blooms.

'Fireworks Mix'
Flowers come in purple, pink, and white, and have very thin petals.

'Gala Lavender'
Lavender-mauve blooms with lighter centers.

'Gala Yellow'
This cultivar produces light yellow, large flowers to 4 inches across.

'Giants of California'
Large, shabby-chic blooms in white, purple, and pink.

'Gremlin Double'
Double flowers in a variety of colors.

'Harlekin Light Rose'
Beautiful, light rose-colored rounded flower heads.

'Harlekin Violet'
To 2-3 feet tall with purple flowers that have cream centers.

'Hazaster Hagen Light Blue'
Flowers with thin, elongated petals in light blue-purple.

'Hi-No-Maru'
2-3 inch white flowers with red centers on plants up to 20 inches tall.

'King Size Apricot'
With large buff-colored to pinkish blooms.

'Juwel Ametrin Lavendel'
Lavender-purple ombre flowers with white centers.

'Lady Coral Chamois'
With pink to salmon-colored blooms.

'Lady Coral Lavender'
With light purple to lavender blooms.

'Lady Coral Salmon Rose'
Ruffled, pinkish-salmon colored flowers on 2-3 foot tall plants.

'Macaroon White'
To between 16 and 20 inches tall with white flowers that have creamy centers.

'Matador Mix'
Classic China Asters in white, purple, lavender, pink, and magenta.

'Matsumoto Apricot'
Apricot-colored blooms on 32-36 inch tall plants.

'Ostrich Feather'
A classic China Aster seed mix that produces red, white, pink, and purple flowers.

'Paeony Duchess'
A line of China Asters with double blooms in a variety of pastel colors.

'Rubens Mix'
Smaller Asters with tightly packed petals in red, pink, and purple, often with yellowish centers.

'Sea Starlet Pink'
Pom-Pom pink flowers with thin petals.

'Single Mix'
A mixture of variously colored single blooms with yellow centers.

'Souffle Light Pink'
Double pink blooms to 3.5 inches across.

'Starlight Rose'
Bushy plant to 1.5 feet tall with dark rose-colored blooms.

'Tower Blue'
Deep silver-violet flowers on tall, productive plants.

'Tower Chamois Apricot'
With light salmon-pink blooms on tall, productive plants.

'Tower Silver'
With white blooms whose petals are tipped with purple.

'Tower Yellow'
With creamy-yellow flowers on tall, productive plants.

'Valkyrie Chamois'
Huge pale apricot-colored flowers on plants that reach 26 to 32 inches tall.

'Valkyrie Pink'
Mauve-pink flowers reminiscent of sea anemones.

'Valkyrie Yellow'
Light pastel yellow blooms.

Caring for Callistephus

China Aster seeds can be sown directly in the garden or started indoors, and can also be purchased as starters from nurseries. It is recommended to move these flowers around the garden each year, never planting them in the same space in successive years; this practice will discourage common disease issues from taking hold. Plant China Asters in full sun to partial shade. They will bloom best in full sun in most climates, but will need some afternoon shade in the warmest areas of their zone range. They prefer well-draining, fertile soil with a pH of between 5.5 and 7.5 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing plants. After planting China Asters, mulch around the base with organic mulching material to help retain soil moisture and suppress weed growth. Keep mulch away from the plant stems, as this can encourage an environment for fungal issues to take hold. Water new plantings regularly as they establish a strong root system. When mature, these flowers also require a good amount of moisture to continue producing their impressive blooms. Keep soil moist, watering when the top inch or two of soil feels dry to the touch. Do not overwater or allow standing water to accumulate in the root zone.

Taller cultivars will need to be staked or otherwise supported to prevent flowering stems from flopping over under the weight of the flower heads. They appreciate regular fertilizations throughout their growing and flowering seasons; in early springtime, feed them with a dressing of organic compost, working it into the soil and mulching over it. Fertilize again in this manner in late springtime to early summertime to elongate the blooming season. Prune off spent blooming when they fade, taking them down to their bases. China Asters are annual plants which are pulled at the end of the growing season and composted. replaced the next year with new plants.

Harvesting Callistephus
Callistephus, or China Aster, are very popular cut flowers. They are available in a wide range of colors, and are available year-round from commercial flower suppliers, though for home gardeners they typically bloom in late summer to fall. As cut flowers, China Asters provide fantastic color and fullness to bouquets. They combine well with many different types of flowers. Taller varieties are most useful in arrangements. Harvest Callistephus flowers just as the outer petals are unfurling. The best time to harvest is in the early morning or late evening when temperatures are at their coolest. Cut flower stems at their base using sharp, clean shears or snips, remove the lower leaves from the stem, and drop them in a bucket of cool water. The vase life of Callistephus cut flowers is between 7 and 14 days.

Propagation

Callistephus can be propagated by using seed. To propagate your China Aster, follow the instructions below:

Propagating Callistephus by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on these plants are pretty easy to spot, they're left behind after flowers have faded and are fluffy and white. Once they have dried out and begun to release their seeds, you can harvest them. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to release the seeds. Once they have been released, take them out of the bag and put them in a container so you can work with them.
In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 10-15 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.