"Add 1 tsp. of liquid food coloring to 1 cup of water. Drizzle the colored water onto the soil surrounding the base of a plant. Wait 24 hours for the water to absorb. Apply another identical dose if the color change was not sufficient."
At one time, my mother had the living room painted in the last three shades of purple - each wall a different color. It worked beautifully with walnut furniture in a Scandinavian, spare design. The carpeting was a brown that matched the walnut, and the sofa was upholstered in textured black. Her collection of blue and amethyst glass bottles picked up the wall colors. This really worked!