Callistephus – China Aster –
There is a single species of an erect, bushy fast growing annual, in this genus. It occurs in stony slopes, wasteland, and cultivated fields in China. It has alternate, ovate-triangular or ovate, coarsely toothed leaves and solitary, daisy like, single, semi double, or double flowers, to 4″ across in shades of white, pink, blue, red, and purple from late summer to autumn. Modern cultivars are available in a wide range of flower heads forms and colors. Use for bedding in annual or informal borders, or in containers. In a frost free site, the will bloom until mid winter. The cultivars provide long lasting cut flowers.
Grow in a sheltered site in fertile, neutral to alkaline, moist but well drained soil in full sun. Water in dry periods. Deadhead to prolong flowering. Tall cultivars require staking. Grow medium and dwarf cultivars for autumn flowering in 5-7″ containers of soil based potting mix in cool, well ventilated condition, with ample water. Do not plant it in the same bed 2 years in a row to protect against aster wilt.
Prone to aster yellows, tomato spotted wilt virus, anthracnose, powdery mildew, stem wilt (yellows), rust, septoria leaf spot, aphids, rosy blister gall, blister beetles, and spider mites.
Comet Series – these cultivars are dwarf growing 10″ tall and 8″ wide and are early flowering, with large, spreading, quill-petalled, double flowers, in a range of colors, including white, pink, blue, purple, scarlet, and yellow, good for containers.