Although balloon flower, Platycodon grandiflorus, is usually grown for its whimsical flower buds, this plant is one tough cookie. Balloon flower is part of the easy growing Bell Flower/Campanula family and you will notice the resemblance right away.
The botanical name means "broad bell", but the open flower is really more of a star shape. However, it's the puffy bud that intrigues gardeners and entices them to grow this plant and that gives it its common name of "Balloon Flower".
Balloon flowers are long-lived perennials that rarely need dividing and are deer resistant.
- Leaves: Alternate, bright green leaves grow along the stems. This is a clump-forming plant.
- Flowers: The flower bud swells up into a puff and slowly opens, passing through a bell shape to a swept back star with five petals, joined at the base. The purple-blue varieties are the most commonly grown, but it also comes in white and shades of pink.
Balloon Flower, Chinese Bellflower, Japanese Bellflower
You will get the most flowers if you plant these in full sun, however, they will be fine in partial shade, especially if the shade comes in the afternoon.
Mature Plant Size
The mature height of balloon flower plants will vary among different varieties and growing conditions.
Most will grow about 1 - 2 ft. tall x 1 ft. wide. Dwarf varieties stay under 1 ft. tall.
Balloon flower can start blooming anytime from mid-summer or later and will repeat bloom if kept deadheaded.
Balloon Flower Growing Tips
Soil: Balloon flowers prefer a slightly acidic soil pH, in the 5.8 - 6.8 range.
Start seed indoors in early spring, Gently press the seed on top of moist soil. They need light to germinate, so do not cover the seed with soil. Seed should germinate within 2 - 3 weeks. Move seedlings into larger pots and slowly harden off, before transplanting outdoors.
You can try making divisions, but the root system is dense and chunky, with a long taproot and doesn't really like being disturbed. To propagate by division, instead of digging up the whole plant, slice a piece of the plant off with a sharp knife. Make sure you get at least a ½ inch piece of the root. Pot it up and keep it moist. If you plan on trying to divide, do it early in the season, when the plants are small, and expect them to take a season or two to start blooming again.
The plants are very late to emerge in the spring. Mark their spot, so you aren't tempted to plant on top of them.
Caring for Balloon Flower Plants
Once established, balloon flowers won't need a lot of supplemental watering. They can handle short periods of drought.
Balloon flowers are not heavy feeders, but a top dressing with compost in the fall will help them replenish the energy they expended blooming. It's also good to add some granular organic fertilizer to the whole bed, in the spring.
For stockier plants, you can pinch them back when they are about 6 inches tall. Deadheading will keep the plants looking good and repeatedly blooming. Don't remove the whole stem, just the faded flowers. The remaining buds will continue to open.
The taller varieties of balloon flower can become a bit floppy, but rather than staking them, just plant them in large drifts and let them support each other.
If you would like to cut the flowers for displays, be sure to sear the cut ends of the stems, to preserve them, or they won't last long.
This is one of those classic plants that is often sold as an unnamed variety.
Don't be afraid to purchase plants without pedigrees; they will grow fine and look lovely. However, there are some excellent named varieties to also look for.
- Platycodon grandiflorus Astra series: The flowers are double with 10 petals in blue, pink or white. A good choice to start from seed.
- Platycodon grandiflorus Fuji series: These are the most commonly sold varieties and the tallest, with 30-inch stems and flowers in blue, pink or white.
- Platycodon grandiflorus "Komachi": Purple-blue flowers that remain in their puffy pillow stage.
- Platycodon grandiflorus "Sentimental Blue": A dwarf variety that grows about 6 inches tall, with lots of 1 - 2-inch purple flowers.
Design Suggestions Using Balloon Flowers
When you're considering companion plants, keep in mind that Balloon flowers won't really start flowering until mid- to late summer, but will continue to flower into fall. The blue varieties go especially well with the pale yellows of lilies, Ratibida, and yarrow. Because the pink and white varieties can be paler than many fall blooming flowers, give extra thought to where you tuck them. They look great next to ornamental grasses, and spiky plants, like Persicaria, Celosia, and Liatris. They also shine next to bold colors like Cosmos "Cosmic Orange".
Pests & Problems of Balloon Flowers
Balloon flowers are virtually pest free. Even the deer don't like them.