Balloon Flower (Platycodon grandiflorus) Easy-to-grow from flower seed, Balloon Flowers are an old-fashioned favorite, and they are as lovely in the garden as they are in the vase. This flower has unique star-shaped blue blossoms, and it blooms late summer and into the fall. Platycodon Grandiflorus has been around forever. The buds form like balloons and then grow until the right time to pop open and form the lovely star-shaped flower. Balloon Flower plants are very hardy perennials that can withstand periods of drought, and they are rarely bothered by disease or insect problems making them virtually a maintenance-free perennial.