In reality, there are no blue-colored roses--many species have incorporated the word "blue" into their names, but to date there aren't any roses that are truly blue in color. Some roses are lilac/lavender in color, however, such as the blueberry hill rose, and the veilchenblau rose. Australia is the center of research into the development of a blue rose. They have located the gene that controls the color blue--but to date it is still in its developmental stages.
The blueberry hill rose is hardy in zones 5 through 9. A mature rose bush will reach a height of 4 feet. The lilac colored blossoms are also very fragrant; they have the fragrance of sweet apples -- which is quite an unusual scent for a rose.
The veilchenblau rose is a very popular climbing rose, which flowers early in the growing season. It is a very fragrant rose, and rose lovers are attracted by not only its lavender-blue blossoms, which have touches of white, but by the fact that it is almost thornless.
The name "Neptune" reminds one of the deep blue seas, yet the rose itself is lavender with touches of purple in color. It is a hybrid tea rose that has a very distinctive sweet fragrance. This rose is known for its disease resistance.
Yet another rose with "blue" in its name, when it actually has lavender blossoms. The shocking blue rose is a floribunda, it has a very distinct citrus fragrance. Shocking blue is valued for its cut flowers.
This is a lovely hybrid tea rose with beautiful lilac colored flowers. Rose growers are attracted to this tea rose for its fragrant blossoms (flowers can have up to 40 petals), and its vigor, as it's known for its ability to quickly re-bloom.
The midnight blue rose is a shrub rose, which is medium-sized rose known for its spicy clove fragrance, its beautiful purple flowers--having up to 20 petals, and its disease resistance.