Blue flowers are among the prettiest colors in a garden. They add serenity and make excellent accompaniments to different colors of flowers. Blue flowers come in different shades of blue including pure blue, bluish-purple, pale blue and lilac. These flowers act as neutralizers when combined with bright colors such as yellow, orange, dark pink and red.
Tall bellflower (Campanula americana) is a perennial that grows up to 6 or more feet high. This blue flower grows mainly in the Great Plains and eastern coast of the United States. The hollow stems are herbaceous, erect, slightly winged (with coarse hairs on wings), simple or branching above. Milky saps appear on stems when punctured.
Alternate, serrated leaves are oblong and measure approximately 7 inches long and 2 inches wide. One to three axillary flowers form on the upper portion of stems. The star-shaped flowers are light blue to violet, flat, and form in elongated clusters on long, branching spikes. They measure approximately 1 inch across and bloom from June to September.
Tall bellflowers prefer moist ground. You will find them in roadside ditches and stream embankments. They grow easily from seeds and do not self-pollinate. Preferring any well-drained medium with a pH of 6 to 7, tall bellflowers are hardy to zones 3 to 8. Plant in full sun to partial shade and allow soil to dry between waterings.
Blue butterfly (Delphinium grandiflorum), also known as Chinese delphinium, is a perennial, blue flower that thrives in regions with relatively cool and moist summers. This mound-forming plant can grow up to 14 inches high and up to 12 inches spread. It has deep green, fern-like foliage with open panicles. Deep blue flowers with five sepals bloom from early summer to fall and measure 1 1/2 inches wide.
Blue butterfly is hardy to zones 3 to 7 and tolerates heat better than regular delphinium, blooming through most of the summer. It grows best in rich, well-drained soil with a basic pH. If your soil is naturally acidic, adding lime will help to provide these conditions. Grow in fertile, medium-moisture, well-drained soil in full sun. Adding compost or manure to the soil as well as using granular fertilizer will result in healthier, stronger plants. Blue butterfly is hardy to zones 3 to 7.
Balloon flower (Platycodon grandiflorus), also known as Chinese bellflower, is an herbaceous summer perennial that comes from East Asia. So named because of their puffy and balloon-like buds, balloon flowers can grow up to 3 feet tall and a spread of 18 inches wide upon maturity. There are dwarf versions that are only 6 inches tall.
The shiny, blue-green or gray leaves have strong leathery texture and measure 1 to 3 inches long. They are narrowly oval, with toothed edges. They grow alternately along plant stems and turn pale yellow in the fall. Deep-blue, unscented flowers bloom early to mid-summer, sometimes longer. The buds inflate and expand into wide bell-shaped flowers that have five petals with pointed tips. Each flower measures up to 3 inches across and has a white star-shaped pistil in the center.
This long-lived perennial prefers full sun and a moist, well-drained site that is acidic. It is hardy to zones 3 to 8.