Black roses are made by immersing cut roses in a botanical dye solution. Naturally black roses do not exist, although certain dark purple varieties appear black when arranged with lighter blooms. According to Florist Chronicles columnist Gina Kellogg, the only way to obtain truly black roses is to dye them with a water-based pigment mix.
Kellogg explains that black dye works best on white and cream roses. The flowers absorb dye thoroughly when they are freshly cut and slightly thirsty. Leaving the cut blossoms out of water for 2 to 3 hours prepares them for dyeing.
To prepare the dye solution, pour warm water into a large non-reactive bowl and add the amount of dye recommended by the florist. Wear rubber gloves and old clothing or a smock. If the roses' stems have leaves or thorns near the cut ends, remove them before laying the flowers in the dye bath.
Black flower dye absorbs in about one hour. When the roses petals appear uniformly black, prepare a clean vase with tepid water and a sprinkling of cut flower preservative granules. Wearing rubber gloves, gently lift the roses out of the dye, pass the stems under running water to remove traces of dye and immediately stick the flowers in the vase.