A blue rose is a type of flower in the Rosa group (part of the Rosaceae family) that has a blue-to-purple color instead of the usual red, white, or yellow. This color is created using artificial methods like dyes. Blue roses are often used to represent mystery or something difficult to reach because they do not naturally occur due to genetic reasons. In 2002, scientists changed the genes of roses to make mauve-colored flowers that contain a blue pigment called delphinidin, which is found in other plants.

Some roses called "blue roses" have been created through crossbreeding, but their color is more accurately described as lilac, such as the variety known as "Blue Moon."

Dyed roses

Blue roses do not grow naturally because roses do not have the special gene needed to create a true blue color. Instead, blue roses are made by dyeing white roses. In a book called Kitāb al-Filāḥah, written in Arabic by an Andalusī agronomist named Ibn al-'Awwām al-Ishbīlī in the 12th century, and later translated into French as Le livre de l'agriculture by J. J. Clement, there are mentions of blue roses known in the Orient. These roses were created by putting blue dye into the bark of their roots.

Genetically engineered roses

Scientists have not yet created a truly blue-colored rose. However, in 2002, after thirteen years of research by an Australian company, Florigene, and a Japanese company, Suntory, scientists made a rose that contains a blue pigment called delphinidin. This was done by changing the genes of a white rose. The company and media called it a blue rose, but its color is actually lavender or pale mauve.

The genetic changes involved three steps: adding two genes and altering the function of another. First, scientists added a gene for delphinidin, a pigment found in pansies, to a type of rose called "Cardinal de Richelieu." This created a dark burgundy rose. Next, scientists used a method called RNA interference (RNAi) to stop the rose’s own genes from making other colors. They blocked a protein called dihydroflavonol 4-reductase (DFR), which is important for color production. They also added a version of the DFR protein that would not be blocked by the RNAi, allowing delphinidin’s color to appear. If this method had worked perfectly, the rose might have been truly blue. However, the RNAi did not stop DFR completely, so the rose still made some natural color, resulting in a red-tinged blue, which is lavender or mauve.

Rose petals are more acidic than pansy petals, and this acidity breaks down the delphinidin in the genetically modified roses. To make the color deeper blue, scientists would need to change the rose’s acidity through traditional breeding or further genetic changes.

By 2008, the genetically modified roses were being grown in test batches at the Martino Cassanova seed institution in South Hampshire, according to a company representative. In 2010, Suntory sold 10,000 of these lavender-colored roses in Japan. Each rose cost between 2,000 and 3,000 yen, or about $22 to $35. The company planned to sell the roses in North America starting in the fall of 2011.

Cultural influence

Because blue roses are not found in nature, they have come to symbolize mystery and something that seems impossible to achieve. In some cultures, there is a belief that if someone owns a blue rose, their wishes may come true.