Platycodon grandiflorus Astra Blue

Platycodon grandiflorus 'Astra Blue' is a new selection of the Japanese bellflower, sometimes called the balloon flower, characterized by a dwarf habit and large and beautiful bright blue-violet flowers. It is an extremely hardy perennial, floriferous and easy to grow in full sun, in any well-drained soil. It produces curious flower buds shaped like small hot air balloons all summer, which open into large star-shaped flowers with wonderfully simple patterns, reminiscent of bellflowers. Sometimes slow to establish, this semi-tuberous plant can be grown in full sun or partial shade, in any well-drained soil that is not too dry.

Platycodon grandiflorus is a plant in the campanula family native to Asia, ranging from China to eastern Siberia, including Japan and Korea. This herbaceous perennial plant grows from a large fibrous root similar to a long turnip, which should not be disturbed once planted.

The 'Astra Blue' variety, shorter than the wild species, emerges quite late in spring. The plant forms a round and dense clump of leafy stems, with an upright and spreading habit, reaching 30cm (12in) in height and diameter. Flowering occurs from June to September, depending on the climate, more abundantly in July-August. The individual flowers develop at the upper part of the stems, in the axils of the leaves. The rounded flower buds, yellow-pink in colour, inflate like small balloons. They open into large campanulate flowers, with a thick texture, star-shaped and 7cm (3in) wide, in a bright blue-mauve colour, beautifully veined with violet. They are visited by pollinating insects and give way to small black round seeds. The foliage is dense, with a matte bluish-green colour, slightly glaucous on the underside. The leaves are opposite on the stems, lanceolate in shape, with irregularly toothed edges. The above-ground parts turn yellow and then take on red hues in autumn, before disappearing in winter. In warm regions, the vegetation dries up after flowering, in summer. Platycodon grandiflorus is deciduous, spending the winter dormant underground. Remember to mark its location to avoid accidental digging.

Hardy and easy to grow, Platycodon grandiflorus 'Astra Blue' thrives in full sun or partial shade, in well-drained, rich and light soils. Plant it in rock gardens, as a border plant or in the background alongside sneezeweeds, Gaillardias, garden marigolds, roses, garden valerians, Phlox paniculata or baby's breath. It also grows well in a deep pot to accommodate its impressive root system, with regular watering. Its large pastel flowers are also beautiful in small wildflower bouquets.