Red, red-orange and yellow are considered to be warm colors
Green, blue, blue-green, blue-violet, and violet are considered
to be cool colors
To the eye, warm colors tend to advance and cool colors tend
to recede. If planted side by side at a distance, the warm colors
will appear closer and the cool colors further away. You can use
these effects to create spatial illusions. Planting cool colored
flowers at the rear of your garden will make the yard seem larger,
warm colors will make the yard seem smaller.
Spot plantings can have similar effects ? seeming to deepen
a part of the yard or bring it closer.
Cool colored plants are good for close-up viewing, warm colors
are good for dramatic displays.
Cool colors can easily be overwhelmed by warm colors.