Platycodon grandiflorus 'Astra Blue' - Balloon Flower

A charming herbaceous perennial, Platycodon grandiflorus ‘Astra Blue’ (often labelled ‘Past Blue’) is known for its balloon-like flower buds that pop open into wide, star-shaped blooms in a soft violet-blue. It forms a tidy clump of dark green foliage and flowers from early to late summer, bringing a whimsical and long-lasting display to borders, containers, and cottage garden schemes.

Platycodon grandiflorus ‘Astra Blue’, commonly known as Balloon Flower, is a reliable, easy-to-grow plant that returns year after year with minimal fuss – and its unique flower buds are a joy to watch as they swell and ‘pop’ open.

Scientific Name
Platycodon grandiflorus ‘Astra Blue’ (from Greek platy = broad and kodon = bell, referring to the shape of the flower; grandiflorus = large-flowered)

Synonyms
Often mislabelled in trade as ‘Past Blue’ – the correct cultivar is ‘Astra Blue’

Also known as Platycodon grandiflorus f. apoyama

Common Name
Balloon Flower

Origin
Native to East Asia – including China, Korea, Japan, and eastern Russia

Pruning Tips
Deadhead spent blooms to extend flowering. Cut back stems after flowering or in autumn when foliage dies back. Mark the spot – it’s slow to re-emerge in spring.

Wildlife Value
Attractive to bees and other pollinators.

Positioning
Full sun to light shade. Best in borders, rock gardens, and containers. Stems may need light support in exposed spots.

Water
Water regularly until established. Prefers evenly moist soil, especially during dry spells, but avoid waterlogging.

Soil
Well-drained, fertile soil is ideal. Tolerates neutral to slightly acidic soil. Improve heavy clay with compost and grit.

Food
Feed lightly in spring with a balanced fertiliser. Too much feeding can cause floppy growth.

Pet-safe
Non-toxic and safe for pets.

Sprouts Top Tips
The buds swell like balloons before blooming – a real delight for children (and adults!) to watch. Avoid disturbing the roots when planting, as it resents being moved once established.