But science may be changing all that soon.  Roses are available in many shades of red and pink, white, lavender, and yellow, but thus far nobody has ever succeeded in making a natural blue rose.  Up until now if you wanted a blue rose, you took a white rose and dyed it blue in some way.  But scientists at Vanderbilt University in Nashville Tennessee may have made a discovery that will make natural blue roses a possibility…

From Going for Blue (ABCNews.com):

In 1986 a biotech company, Florigene, was founded in Melbourne, Australia with the single goal of creating a blue rose. … They still haven't claimed making a blue rose, although they're coy about just what they've accomplished. …

Any developments toward achieving the blue beauty will remain top secret, Mason explains, until Florigene announces it has a blue rose. Meanwhile, medical researchers in Tennesse think they may have stumbled upon a shortcut.

As will be detailed in the Journal of Medicinal Chemistry, biochemist Peter Guengerich and his assistant Elizabeth Gillam were in the process of trying to understand how the human liver breaks down drugs when they came across a human liver enzyme that had a startling effect.

“When we moved the enzyme into bacteria, the bacteria turned blue,” he says. “It was a complete surprise.” …

These scientists have since gone on to transplant the gene for this enzyme resulting in roses with blue spots on the stem.  The liver enzyme apparently generates the blue pigment in a much simpler way than classic blue flowers (like petunias) do, and may therefore represent an easier route to blue roses.

Pretty neat!