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Platycodon grandiflorus

How to grow platycodon (balloon flower)

All you need to know about growing platycodon (balloon flower), in this Grow Guide.

  • Plant size

    50cm height

    50cm spread

Platycodon grandiflorus is a clump-forming herbaceous perennial that bears starry flowers in summer. These are mostly in shades of vivid violet-blue, although white and pink cultivars are also available.

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It is a member of the Campanula family, and its flowers look similar to those of campanulas, or bell flowers. Its distinctive buds look like balloons that are about to burst – or mini hot air balloons – hence its common name, balloon flower.

Platycodon hails from East Asia and is a popular plant in Korea, Japan, China and the US. Perfect for the front of a cottage or herbaceous border or a container, it deserves to be more widely grown in the UK – it has the prestigious Royal Horticultural Society Award of Garden Merit (AGM). It also makes a good cut flower.

How to grow platycodon

Grow platycodon at the front of a border or in a container, in fertile, moist but well drained soil. It will thrive in sun or partial shade. Cut back the flowered stems in autumn. Platycodons suffer when their roots are disturbed, so it’s best not to divide or move your plants once established.

Platycodon: jump links


Where to grow platycodon

Platycodon growing in a pot
Platycodon growing in a pot

Grow platycodon in fertile soil that’s moist but well-drained, in sun or partial shade. Avoid growing it in heavy, waterlogged soil.


How to plant platycodon

Planting platycodon in a pot
Planting platycodon in a pot

Dig a hole that is the same depth and a little wider than the rootball, backfill with soil and firm in gently to avoid damaging the roots. Water in well. If your garden has clay soil, add some organic matter, such as garden compost, to the planting hole. If growing in a pot, plant into peat-free, multipurpose compost.


Caring for platycodon

Platycodon grandiflorus. Getty Images
Platycodon grandiflorus. Getty Images

Deadhead the faded flowers to keep the plant blooming well, then cut back the faded flower stems to the ground in autumn. The foliage is late to appear the following spring, so it’s a good idea to mark where the plant is when it has died back, to prevent disturbing it while it is dormant – it has fleshy tap roots that are easily damaged.

Feed with an all-purpose feed in spring, and mulch in autumn.

Some taller varieties have a tendency to flop, so may need staking. Alternatively, trim the stems back a little in spring to prevent them becoming too tall.


How to propagate platycodon

Sow playtcodon seeds in pots under cover in spring – they need light to germinate, so do not cover the compost. Harden off and gently transplant to their final position once all risk of frost has passed. Alternatively, sow direct from late spring onwards. The plants will flower the following year.


Growing platycodon: problem solving

Platycodon is generally disease free. Slugs and snails may be a problem when the foliage emerges in spring, so protect the plant early on.

Plants can get leggy if they don’t have enough sun.

Root rot can be a problem in very heavy, wet soils.


Advice on buying platycodon

  • You may find playtcodon in garden centres – if not, buy online. They are often sold as bare-root plants, despatched in winter
  • Check that you have the right conditions – platycodon like moist but well drained soil, and full sun or partial shade

Where to buy platycodon online

Best varieties of platycodon to grow

Platycodon grandiflorus ‘Astra Blue’ – starry violet blue flowers. Said to have good heat tolerance in summer. Height x Spread: 50cm x 50cm

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Platycodon grandiflorus ‘Fuji Blue’ – blue-purple, almost translucent petals, with delicate veins. H x S: 45cm x 45cm