No trimming required, this hydrangea blooms large mopheads throughout summer. It works well in cooler areas. For optimum blue, acidify soil and use aluminum sulfate.
The deep-blue calyxes keep the color after the blooms fade. New flower spikes appear throughout summer, which is preferable.
This smaller, blue-flowered marvel has large, globe-like flower clusters atop thin leaves. The seedpods are nearly as beautiful as the petals.
Blue Chiffon has exquisite stems and delicate blossoms from June to October. Birds and butterflies love its lace centred blossoms.
This old-fashioned favorite, dubbed "bachelor's buttons," is popular in cutting gardens. Crayola crayons recreate the characteristic blue hue.
The non-vining relative of morning glory blooms delicate true-blue flowers from early summer to the first frost and spreads little more than 2 feet.
This stunning sapphire-blue iris features huge ruffled petals and vivid yellow beards. They debut in spring and return in summer.