Roses grow in a variety of colours, including red, yellow and white. However, there are other colours that you may wish to have for special occasions such as teal blue, emerald green or black. Unfortunately, these colours of roses do not exist in nature, but that doesn't mean you're out of luck. You can experiment with white roses and food colouring to achieve the different colours you want.
Fill a glass or disposable large plastic cup with a cup of water.
Add a few drops of food colouring or floral dye of the colour of your choice into the water until you have the desired shade. The more dye you add, the darker the white rose will turn. If you add too much dye, dilute with water.
Cut a 13mm (1/2 inch) from the stem on a diagonal angle so the rose will absorb the coloured water.
Place the stem in the water for a day or two, checking periodically to monitor the colour change. Once you have the desired colour, remove it from the coloured water, snip the stem and place the rose or roses in a vase of fresh water.
Wear gardening gloves when handling roses to protect yourself from their thorns.