Space or transplant 30-45cm (12-18″) apart. This spacing is key to success later in the season, so please follow the guidance. Do not pinch back young plants. Water regularly during dry spells. This plant is particularly sensitive to over-watering, and will not thrive if over-crowded, poorly ventilated, or situated close to a heat-reflecting surface. Mulch around the plants in summer to help keep the roots cool.
Callistephus is prone to a bacteria-like organism known as aster yellows. If yellow spots become an obvious problem, destroy any infected plant before the condition spreads to others. Practice strict garden rotation with China Asters: never plant them in the same spot year after year.