Everything these days has a color theme and gardens are no exception. Single colors or combinations of colors are used to create a certain garden style or mood. Blue theme gardens have a relaxing effect and there are enough different shades of blue so a blue themed garden will not come off as monochromatic.
Variegated Sweet Iris has blueish lavender flowers that are very fragrant and bloom in the early summer. They can grow to 30 inches tall, look great against a white fence and also make good container plants. They are hardy in zones 4 to 9 and are deer resistant.
Blue Pimpernel grows 9 inches high and has a 20 inch spread, has light blue petals with red centers and blooms from late spring to early fall. It can be planted as a perennial in zones 9 to 11.
Anchusa Undulata is drought resistant and produces small dark blue purple flowers. It is also deer and snail resistant. It can be grown as a perennial in zones 9 to 11.
Campanula Blue Clipshas heart shaped leaves and blue bell shaped flowers that will bloom though out the summer. It will grow to about 12 inches high and is hardy in zones 3 to 8.
Wonder of Staffa Aster looks like a daisy with its lavender blue petals and yellow center. It blooms all summer into the fall, is deer resistant and is hardy in zones 5 to 8.
Blue Butterfly Delphinium has a deep blue color. It attracts butterflies but deer will leave it alone. It grows to about 14 inches high, making it a perfect choice for a border. Flowers appear in the early part of summer and it will bloom all season long. It is hardy in zones 4 – 8.
Blue Bird Rose of Sharo n will bloom for a minimum of three months from late summer all the way to first frost. It can get as tall as 8 feet, is deer resistant, and is hardy in zones 4 to 9.
Jackmanii Climbing Clematis grows up to 14 feet height and makes a great privacy plant. The purple blue flowers bloom from mid summer through the fall and it is hardy in zones 3 to 8.
Evergreen Vinca grows 6 inches high and has blue star shaped flowers that bloom in the early spring. It likes shade, so it can go under trees and it is deer resistant. It is hardy in zones 4 to 9.
Trailing Bellflower is a trailing ground cover that grows 8 inches long and 28 inches wide. It is an evergreen with star shaped lilac blue flowers. It can also be used in hanging pot and it attracts butterflies. It is hardy in zones 4 to 7.