Balloon flower (Platycodon grandiflorus 'Hakone Blue')

Overview

The Platycodon grandiflorus ‘Hakone Blue’ is a highly valued herbaceous perennial, renowned for its unique, balloon-shaped flower buds that puff up before dramatically opening into outward-facing, bell-shaped blossoms. This specific cultivar, the ‘Hakone Blue’ Balloon flower, is especially sought after for its bright, double blue flowers, providing excellent summer color. As a clump-forming perennial, it establishes reliably in its appropriate hardy zones and requires minimal intervention once situated.

Native to meadows and slopes across East Asia, this plant offers significant aesthetic appeal with its toothed, blue-green foliage complementing the summer blooms. Gardeners appreciate the longevity of the flower display, which runs from June through August, making the Balloon flower a staple in mixed borders. Its relatively low maintenance profile reinforces its status as a reliable performer for both novice and experienced gardeners.

The species name, Platycodon grandiflorus, translates beautifully, referencing the genus’s broad, bell-shaped flowers. Incorporating Platycodon grandiflorus ‘Hakone Blue’ into your landscape introduces reliable vertical interest and a distinctive texture to summer plantings. Ensure proper soil drainage to maximize vigor and enjoy this resilient summer bloomer.

Fast Facts

• Plant Family: Campanulaceae
• Plant Type: Herbaceous perennial
• Hardiness Zones: USDA Zones 3-8
• Size at Maturity:
  • Height: 1.5-2 ft
  • Spread: 1-1.5 ft
• Bloom Time: June to August
• Bloom Description: Blue
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Low

How to Grow

The Platycodon grandiflorus ‘Hakone Blue’ thrives best when planted in light, organically rich, medium-moisture, well-drained loams. Location selection is key; aim for full sun exposure for the most prolific blooming, though partial shade is tolerated well. Planting is best done in spring, allowing the roots to establish before winter sets in. Above all, rigorously avoid wet or compacted soils, as this invites root rot issues which can quickly compromise this plant.

Once established, the Platycodon grandiflorus generally requires medium water; water consistently during dry spells but never allow the plant to sit in soggy conditions. Maintenance for the Balloon flower is generally low. Fertilization is rarely necessary if the soil is rich; excessive feeding can lead to weak, floppy stems. Deadheading spent flowers is recommended to prolong the bloom period throughout the hot summer months.

Be extremely patient in the spring, as new stems for Platycodon grandiflorus ‘Hakone Blue’ emerge very late. Gardeners must take care not to cultivate early in the season, as the fragile crowns are easily damaged. Many gardeners leave the old, upright stems in place over winter to help mark the exact location of emerging new growth. Taller specimens may require staking to prevent stems from flopping, or you can proactively cut stems back by half in May to reduce overall height and improve sturdiness.

Landscape Uses

The compact size and charming blooms of the Balloon flower make Platycodon grandiflorus ‘Hakone Blue’ exceptionally versatile in the garden design. They are ideal for planting at the front of mixed borders, where their summer color can be easily viewed. Their moderate height also makes them superb for rock gardens, providing soft, mounded color among hardscaping elements.

Containers are another excellent application for the Balloon flower, offering portable summer beauty near patios or entryways. When used for edging, the uniform height and sturdy clump habit of this perennial help define pathways and garden beds effectively. Pair the blue flowers of Platycodon grandiflorus ‘Hakone Blue’ with contrasting foliage colors, such as silvery artemisias or deep burgundy heucheras, to make the blue truly pop during midsummer.

Standout Features

Flower Qualities

• Showy

Noteworthy Characteristics

Platycodon grandiflorus, commonly called balloon flower, is a clump-forming perennial that is so named because its flower buds puff up like balloons before bursting open into outward-to-upward-facing, bell-shaped flowers with five pointed lobes. Plants are native to slopes and meadows in China, Japan, Korea and Siberia. Purple-blue flowers (to 2-3” across) bloom throughout summer, singly or in small clusters, atop stems typically growing to 30” tall. Ovate to lance-shaped, toothed, blue-green leaves (to 2” long).Genus name comes from the Greek words platys meaning broad and kodon meaning a bell for the shape of the corolla.Specific epithet means large-flowered.‘Hakone Blue’ features bright blue double flowers (2-3” across) that appear singly or in small clusters atop stems typically growing to 18-24” tall. Dentate, lance-shaped leaves. Blooms throughout the summer.

Tolerances

Potential Problems

Generally, the Balloon flower exhibits resistance to most serious insect pests and diseases, which contributes to its low maintenance rating. The primary cultural risk involves root rot, which occurs specifically when the soil is overly moist or poorly drained, contradicting its need for medium moisture. Gardeners should actively monitor for slugs and snails, which may occasionally chew on the emerging spring growth or the foliage. Prevention involves diligent scouting and applying appropriate baits or barriers early in the season.

Frequently Asked Questions

What hardiness zones is Platycodon grandiflorus ‘Hakone Blue’ suitable for?

This reliable herbaceous perennial is hardy across USDA Zones 3 through 8, offering a wide range of successful locations for planting.

How large does Balloon flower grow?

The Platycodon grandiflorus ‘Hakone Blue’ typically reaches heights between 1.5 to 2 feet tall, spreading moderately to between 1 and 1.5 feet wide.

When does Balloon flower bloom?

You can expect the attractive, blue blooms of the Platycodon grandiflorus ‘Hakone Blue’ to appear consistently from June right through August.

What sun exposure does Balloon flower need?

For optimal performance, this plant prefers a location that receives full sun, though it will tolerate situations offering partial shade during the hottest part of the afternoon.

Conclusion

The Platycodon grandiflorus ‘Hakone Blue’ offers gardeners reliable, showy summer color with minimal fuss due to its low maintenance needs and general pest resistance. Its unique balloon buds and vibrant blue flowers solidify its place in successful cottage or contemporary gardens. Before planting, confirm your local hardiness zone falls between 3 and 8 and ensure your soil offers excellent drainage to enjoy this lovely Balloon flower iteration for years to come.

Companion Planting

Selecting suitable neighbors is key to a successful border featuring Platycodon grandiflorus ‘Hakone Blue’. Due to its cultural needs—well-drained soil and medium water—companion plants should share these requirements. Hostas, while preferring more shade, can work if the Balloon flower is sited in its preferred morning sun/afternoon shade location; they provide excellent leafy contrast. For sunny spots, consider pairing the blue flowers with white or yellow blooms, such as Shasta Daisies or Coreopsis varieties. These companions bloom concurrently, creating vibrant, complementary color palettes throughout the summer.

Seasonal Care Calendar

Managing the late emergence of Platycodon grandiflorus ‘Hakone Blue’ requires patience in the spring. In early spring, resist the urge to clean up old stems until new growth is clearly visible—this minimizes accidental crown damage. As summer peaks, deadheading faded double blue flowers will encourage a continuous flush of blooms well into August. In late fall, after the foliage has yellowed naturally, cut the stems back to the ground for winter cleanup. No special winter protection is usually required for established plants in USDA Zones 3-8, provided drainage is sufficient.