Balloon flowers (Platycodons grandiflorus) are beautiful summer-blooming perennials that come in a range of flower colors including, pink, white, and blue. They grow to a height of about 3 feet and thrive in full sun on well-drained soil.
The Chicago Botanic Garden trailed 19 different varieties of balloon flowers in their USDA zone 5 gardens. They evaluated plants for bloom period, flower color and size, growth habit, disease and pest problems, and winter survivability. Varieties were given a 1 to 5 overall rating, with 5 being the highest.
After five years of evaluating balloon flower varieties none of the varieties tested scored an average of 5, but 12 varieties were in the 4 category. Some of the best were 'Astra Blue', Baby Blue', and 'Sentimental Blue'. The Fuji and Hakone series all averaged scores of 4 regardless of the flower color. For example, 'Fuji Blue', 'Fuji Pink', 'Fuji White', 'Hakone Blue', and 'Hakone White' were all top performers.
For more information on this balloon flower trial, go to: Chicago Botanic Gardens