Platycodon grandiflorus 'Hakone Blue' (double)
(Balloon flower) Gorgeous large purple-blue flowers 5-7cm across, with two rows of petals, creating a double, layered effect, opening from balloon-like buds. A hardy perennial that dies back to an underground tuber in winter, then comes up again in late spring, getting better every year. Full sun to dappled shade. 40-60cm x 30cm. 9cm pot.