Take two glasses of equal size and fill them with water.
Pour the red dye into one of the glass and stir to dissolve it in the water. You can replace the red dye with any color that you like.
Note: Make sure to use water soluble dyes. However, if you do not have dye available at hand, then simply replace it with food coloring in the shade of your choice.
Gently slit the stem of the white flower with the help of a sharp blade.
Note: White carnation is the best choice to conduct this experiment.
Now, place one half of the stem of the white flower in glass with plain water and the other one in the glass with red dye.
Leave it for few hours until one side of the white flower turned to red color.
Why does this happen?
One side of the white flower changed its color as the capillary action carries water from the soil to various parts of the plants and flowers. The water goes up through sap tubes that create the required capillary force.