Platycodon grandiflorurn is a perennial member of the bell flower family. Because of the curious inflated form of its flowerbuds it is commonly called balloon flower. These `balloons' open to become bells of blue or white. The compact species best for rock gardens is P. g. mariesii, with deep blue flowers 5cm/2in across. There are no named varieties.

GROWING Plant in late autumn or early spring in well-drained soil in a sunny position. Balloon flowers are slow to establish themselves and dislike disturbance. It is a good idea to mark the site so that the roots are not inadvertently damaged when top growth has died down.

PROPAGATION Divide mature (4-year-old) plants in spring and replant, handling the roots carefully. Raising from seed is more reliable. Sow seeds in spring in shallow drills in a nursery bed. Transplant to the flowering site when the seedlings are large enough to handle but before the fleshy roots have formed.

POSSIBLE PROBLEMS Generally trouble-free.