Balloon flower "Hakone White"

Chinese bellflower "Hakone White" (balloon flower) - Platycodon grandiflorum.
Family: Campanulaceae.
Origin: Japan and China.
Special Features: flower buds which appear inflated (balloon-like) open into double blossoms leaves.
Colour: White Natural.
Flowering Period: June - August.
Winter Hardiness Zones: Z3-Z8.
Growth Habit: compact, upright habit.
Foliage: the lanceolate to ovate shaped leaves are arranged very neatly along the stems.
Height with Flower: 50 cm.
Spacing between Plants: 40 cm.
Soil Requirement: well-drained soils, 
Location: full sun to partial shade.
Use: long-lived perennial well-suited with Eryngium "Blaukappe", Echinacea paradoxa and Penstemon "Husker Red", combined with tall bells, adenophora, low phlox, gypsophila.
Specialities: great for the front of the border; suitable for use as a cut flower.

Location: prefers open sunny places, but tolerates partial shade.
Soil: moderately dry, fresh, loose and rich in nutrients, pH 5.5 - 6.8. Needs drainage. Plants do not tolerate stagnant groundwater.
Care: water and fertilize moderately. Cut off in the fall. It is winter-hardy, but in case of a snowless winter, mulching or sheltering with a dry leaf is desirable.
Reproduction: by seeds that are sown in open ground in autumn or spring. 1,0 g = 1000-1350 seeds.
When spring sowing, cold stratification is desirable for 1-3 months. In this case, the shoots will be more friendly. Seedlings require sufficient lighting and uniform moderate watering. They bloom in the second or fourth year.
Planting is carried out, maintaining a distance between plants of 25-30 cm. They are grown in one place for at least five years. Mature plants do not tolerate transplantation well due to the fragility of fragile roots. Vegetatively propagated by basal cuttings taken from the "heel" in the spring at the beginning of growth.
Use: very effective in small groups on the lawn, good in bouquets, ideal for rocky hills. It looks very nice in bouquets, cutting is done when all the flowers open. Flowering is plentiful and long.

Cultural Tips: 
Seeds per Gram: 1000-1350 seeds.
Seeding Recommendation: 2 g / 1000 plants.
Sowing Rate: 2 seeds per cell.
Plug tray recommended size(s): 128 or 288.
Germination: Rapidly germinating (2 to 3 weeks), keep seed in constant moisture (not wet) with temperatures of about +20°C. The seed must be covered thinly. Keep in cooler conditions after germination occurs. The germination might be slower and more irregular. This poses no problems.
Scheduling.
Best Sowing Dates: Anytime Sowing to Germination: 2 - 3 weeks.
Germination to Transplant: 4 - 6 weeks.
Transplanting to Salable Plant: 6 - 8 weeks.
Cutting-Back at Transplanting: Cut-back once to keep more compact.
Growing On: Container Size(s): 1-2 plugs per 11/12 cm.
Vernalization: Some flowering will occur the first year without vernalization, but improved flowering will occur the 2nd year; and 3-10 weeks of cool temperatures might benefit fuller flowering in the first year.
Forcing: There has been no research on "Hakone White", but an obvious place to experiment - following vernalization - would be raising daytime temperatures to 15° - 17°C. Provide 16 hours of continuous lighting. During the short days of winter, provide a night interruption lighting of 4 hours between 10:00 p.m. and 2:00 a.m. Some later flowering species can be forced in 14 - 16 weeks and perhaps sooner at warmer temperatures. Further experiments are warranted with "Hakone White".

Chinese bellflower, balloon flower white. Bot. syn.: Рlatycodon grandiflorus (Jacq.) A. DC.