Balloon flower

Balloon flower: how do you recognise it?

Habit

Upright clump about 60 cm tall and 30 cm wide, with sparsely branched stems.

Leaves

Oval, 3–7 cm, toothed and blue-green; they turn yellow in autumn before dying back.

Flower

Broadly bell- to star-shaped, 5–7 cm across, with five points, opening from inflated balloon buds from July to September.

Colour

Violet-blue with darker veins; also white and soft pink.

Milky sap

Broken stems ooze a white milky sap, as in many members of the bellflower family.

Roots

A thick, fleshy taproot, which is why it dislikes being moved.

Flowering: July–September · Sowing: March · Plants: April–May · Pruning: October

Why grow it?

• Large, blue star-shaped flowers from July to September, a colour that always works in a border.
• The balloon-shaped buds are an attraction in themselves, especially for children.
• Bees and bumblebees visit the open flowers.
• Once established it can stay in the same place for a very long time.
• Good as a cut flower and suitable for a deep pot.

Balloon flower: where does it grow best?

• Sun to light partial shade.
• Well-drained sandy or loamy soil, acid to neutral.
• Moderately moist; wet soil in winter rots the fleshy roots.
• Plant 30 cm apart and choose a permanent spot from the start: it does not like being moved.

Light

Sun and partial shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

0.6 m tall, 0.3 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Hardy geranium: Low and flowering at the base, in the same sun or light shade.
• Lady’s mantle: Soft yellow flowers and fresh green leaves beside the blue.
• Roses: A classic combination in a summer border.
• Catmint: Lavender-blue clouds that match the blue of the balloon flower.
• Spring bulbs: They fill the gap in spring, before the balloon flower appears; plant them beside it, not on top of the root.

Balloon flower: when and how to plant it?

Plant in April–May.

1. Plant in April–May, once the soil has warmed up.
2. Loosen the soil deeply, as the taproot goes down a long way; in heavy soil mix in coarse sand.
3. Set the plant at the same depth as it was in the pot, with the crown just at soil level.
4. Plant 30 cm apart and firm the soil.
5. Water well and keep the soil moist for the first few weeks.
6. Put a label or cane beside the plant straight away: every year it appears only late in spring.

Care

Watering

In dry spells in the first year; after that only in long droughts.

Feeding

A thin layer of compost in spring is enough.

Support

Tall plants sometimes flop; in June put a few canes or a ring around the clump.

Spent flowers

Snip off faded flowers regularly: more new buds will then open.

Marking

Leave the label in place all year so that you do not damage the plant in spring when weeding or planting.

Tip: It appears only late in spring, so mark the spot with a cane or label to avoid digging it up. The buds swell like little balloons before they pop open.

Balloon flower: when to prune it?

Pruning months: October.

When: In October, when the stems turn yellow, cut them down to just above the ground. In summer, snip off faded flowers.

How:

• Cut off faded flowers one by one, just below the flower.
• In October, cut all the stems down to 5 cm above the ground, so you can still see where the plant is.
• Put in a label straight away: in spring there is nothing to see for a long time.

Caution: Take care when hoeing or digging in spring: the young shoots appear late, often not until May.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow indoors in March on moist seed compost and do not cover the seed: it needs light and germinates at 18–20 °C in 2–3 weeks. Seedlings sometimes flower in the first year, but usually from the second.

Division

Tricky because of the taproot. Only on older clumps: in April, carefully cut away a piece with buds and root and replant it straight away.

Balloon flower: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed.
• The plant dies back completely in autumn and stays invisible until late spring: mark the spot.
• Wet soil in winter is its worst enemy; make sure drainage is good.
• In a pot: keep the pot dry and sheltered in winter, for example under a porch roof.

Diseases and pests

• Slugs: They love the young shoots in May. Protect them with a collar or pick the slugs off in the evening.
• Dug up by mistake: Because it appears so late, it is often damaged by accident. Mark the spot in autumn.
• Root rot: The plant fails to come up after a wet winter. Plant in well-drained soil.
• Flopping: In rich soil or shade the stems go soft. Support them in good time or choose a lower-growing form.

Through the year

• March: Sow indoors.
• April: Plant. Leave the spot alone: the plant is not visible yet.
• May: Plant. Young shoots appear. Watch for slugs.
• June: Support tall plants.
• July: Flowering begins. Snip off spent flowers.
• August: In full flower. Water in dry spells.
• September: Last flowers. Snip off spent flowers.
• October: Cut down yellowed stems and mark the spot.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The name Platycodon comes from the Greek words for broad and bell, after the shape of the flower.
• In Korea the root is known as doraji and is eaten as a vegetable.
• It is the only species in its genus.