Use food colour to change the colour of orchid blooms. This process works most effectively with white orchids. The colour changes when water moves up the stem through the xylem vessels. The water carries the dye to all parts of the plant. The petals themselves are the only part of the flower that changes colour. Because flowers wilt quickly without water, it's important to dye them soon after cutting.
Fill a vase or tall jar 2/3 full of water.
Add two to three drops of food colouring. Stir the dye into the water.
Cut the ends of the orchid blooms at an angle and place them into the water.
Set the flowers in a sunny spot. The water will move up the stem and to the petals, causing a colour change. Remove from the water once they reach the desired colour.