Until very recently, blue roses did not exist in nature, and they've only now become available through the use of genetic engineering. The first blue rose was created artificially in 2004 by engineers in Japan, according to University of Illinois Extension horticulture educator Jennifer Schultz Nelson. Buying these blue roses, however, can be quite expensive. One alternative is to dye roses blue at home using food coloring. It's an easy project and will result in strikingly blue flowers in about 24 hours. If you have some extra white roses from your flower garden this year, you can dye them blue and add interest to your cut flower displays.
Fill a flower vase about half full with water. Make sure to use a vase that's large enough to hold all of your roses. Because it takes so much time to dye the flowers, it's easier to create a large batch of blue roses than several smaller batches.
Add about five drops of blue food coloring to the water for each rose you'll be dyeing. Add more if necessary, until the water is a deep blue color. If you want lighter, pastel blue roses, add a little less coloring. Experiment until you've created the hue you desire.
Cut 1 to 2 inches from the bottom of each white rose stem with a sharp knife or scissors. This will make it easier for the water and food coloring to penetrate the stems and dye the roses blue.
Place the cut white roses into the vase and allow them to sit for 24 to 72 hours. The longer they're left in place, the darker blue they'll become. Check them every few hours after the first day to make sure they don't become too dark.
Remove the blue roses from the vase once they've turned the color you desire. Wipe the stems to remove any excess food coloring. Pace them in a vase filled with fresh water, use them in flower displays, or wrap in plastic and give as a gift.