The blue color in flowers results from the plant having the gene for blue coloring. Some flowers, such as roses, don't have the gene. Therefore, it's not possible to breed a true blue rose without altering the chromosomes of the rose. Other flowers change color from pink to blue, such as hydrangeas, based on the alkalinity or acid levels of the soil. It is not possible to naturally change a white hydrangea to blue, according to the Hydrangeas Hydrangeas website, but you can artificially change the color.
Add drops of food coloring to 4 oz. of water. The more coloring that is added, the deeper the blue color.
Select flowers that make good cutting flowers and have thin petals. Examples would be roses, chrysanthemums, carnations, daisies and mini carnations.
Cut 1/2 inch of the stems of the flowers. Remove the leaves.
Place the stems in the blue water. The flower will draw up the water through its stem. The color will appear first in the veins of the flower and eventually color the entire petal as well. The longer the flower is left in the dye bath, the deeper the color.
Re-cut the stems and place back in the water after 24 hours if the color isn't dark enough.
Floral Spray Paint
Cut 1/2 inch off the stems of the flowers and remove the leaves. Place stems in an ice-water bath for 1 hour.
Hold the stem of the flower and lightly coat the petals with the floral spray paint. Add additional coats of paints to achieve the depth of color you want.
Return flowers to the ice bath until all flowers have been sprayed and the paint is dry. Most floral spray paint has little odor and dries quickly.
About this Author
Katie Rosehill holds an MBA from Arizona State University. She began her writing career soon after college and has written website content and e-books. Her articles have appeared on GardenGuides.com, eHow, and GolfLinks. Favorite topics include personal finance - that MBA does come in handy sometimes - weddings and gardening.