Colors opposite each other on a color wheel that contrast with each other: red-green, blue-orange, and yellow-violet.

either one of two chromatic colors that when mixed together give white (in the case of lights) or gray (in the case of pigments); "yellow and blue are complementaries"

Colors which lie directly opposite each other on the color wheel are as unlike one another as they can be. The two colors selected contrast with each other to make a bold statement (ie: red & green, blue & orange, etc.)

A color harmony of two colors exactly opposite each other on the color wheel.

a color that's opposite another on the color wheel. Red and green are complementary; so are blue and orange. Complementary colors intensify each other, making each other "pop." Use them to create focal points, to highlight a particular area of the garden.