How to grow platycodon (balloon flower)
All you need to know about growing platycodon (balloon flower), in this Grow Guide.
Plant Size: Height: 50 Spread: 50 |
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. It's 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 holds the prestigious Royal Horticultural Society Award of Garden Merit (AGM), and also makes a good cut flower.
Where to grow platycodon
The best place to grow platycodon is at the front of a border or rockery, or in a container in fertile, moist but well drained soil. It'll thrive in sun or partial shade. Avoid growing it in heavy, waterlogged soil.
When to plant platycodon
Platycodon is best planted in spring to give it time to establish before it flowers in July and August.
How to plant platycodon
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.
- Dig a hole that is the same depth and a little wider than the rootball, and place the plant in it.
- Back-fill with soil and firm around the area gently, to avoid damaging the roots.
- Water in well.
How to care for platycodon
Caring for a Platycodon grandiflora is easy. Young plants need to be watered in dry periods until established, but after that they can cope with some drought and shouldn’t need much watering. Feed with an all-purpose feed in spring.
Platycodon foliage is late to appear in spring, so it's a good idea to mark the position of the plant when it dies back, to prevent disturbing it during the dormant period. Plants have fleshy tap roots that are easily damaged, so it's best not to divide or move them once established. To protect platycodon over winter, mulch plants in the autumn, ensuring the mulch doesn’t touch the stems.
How to prune platycodon
Deadhead the faded flowers to keep the plant blooming well, then cut back flower stems to the ground in spring just before the new shoots appear. This allows the old foliage to protect the plant through the winter and also provides a good habitat for overwintering insects. 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.
Pests and diseases
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 and 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
Platycodon grandiflorus ‘Fuji Mix’ – blue-purple, pink and white flowers, almost translucent petals, with delicate veins. H x S: 50cm x 50cm
Frequently asked questions
Do platycodon come back every year?
Yes, platycodon are perennial and should be hardy in most areas of the UK, especially when protected overwinter with a mulch, so they should come back every year.
Can you keep platycodon in pots?
You can keep platycodon in pots. Plant in free-draining peat-free multi-purpose compost in a container that's at least 25cm deep to give sufficient room for the tap root. Plants in pots will need regular watering and top dressing with compost in spring.
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