Callistephus is genus of flowering plants native to Asia with a single known species, C. chinensis or the China aster. These plants have been heavily bred to produce an array of cultivars designed for various garden uses. They are readily available at nurseries or garden suppliers and gardeners can also order seeds from catalogs or receive seeds through exchanges with other gardeners. Seed exchange communities online can be an excellent way to network with gardeners out of the area and access unusual and rare seeds.
The China aster is an annual plant, producing toothed ovate leaves on upright stalks. Depending on the cultivar, the flower may consist of a single disc floret, or a ray surrounding a disk. The flowers can be pink, purple, white, and blue, and come in a range of hues. Specialty cultivars are sometimes named after the colors of their flowers to distinguish them from other Callistephus that might be commercially available. Gardeners can also make their own cultivars by cross-breeding different varietals in their gardens.
In addition to being available in full size, dwarf cultivars are also available. They can be grown directly in the ground or in containers and are very hardy. These annuals do not bloom for very long, but make excellent cut flowers during their flowering period. Callistephus flowers also press and dry well. They may be used in crafts like wreaths and papermaking by crafters who work with dried and pressed flowers.
People interested in growing Callistephis will need sandy loam and an area with full sun to part shade. While other soil mixes can be used, it is advisable to use well drained, light soil. Heavy, clumping soil makes for poor growing conditions for these plants. Fertilizers can be added to encourage the plants to grow healthy and strong. Callistephus makes an excellent massed planting or border and can be paired with companion plants like hollyhocks, chrysanthemums, and carnations, among many others.
Seedlings can be started in a greenhouse or a warm corner of the house. In warm regions of the world, the seeds can be planted directly in the soil where the adult plants will grow. Clean soil should be used to limit the risk of fungal infections. The soil should be kept moist and warm while the seeds germinate. Once the plants are established, they can be lightly watered as needed. Some of the flowers should be allowed to go to seed to produce seeds for the following year, and the Callistephus plants can be removed after they start to die off.