As stated on Page 1, proper use of color can influence mood and perception. For instance, red, yellow and orange are considered "warm colors" and may excite the viewer. Blue, purple and green are considered "cool colors" and are more likely to relax you. Thus for a meditation garden, blue and/or purple flowers would be a logical choice.
If your backyard comprises just a small area, you can alter the viewer's perception by using a combination of warm and cool colors. Place flowers with warm colors in the foreground. Behind them, install flowers with cool colors, starting with darker shades (e.g., purple), followed by shades that are successively lighter. This will create an illusion of depth. You can also create this illusion by placing larger plant material in the foreground, then tapering off the size of your plants as you work your way in deeper (the perception that the latter are receding into the distance will be magnified).
Here's another trick: with warm colors like red, you may perceive large spaces to be more intimate. The warm colors appear to come forward in the landscape, and seem closer than they are in reality -- thereby scaling down the whole landscape in the process.
The warm colors are born attention-grabbers, since they bring a mood that does not relax, but rather rouses the viewer. If you wish to draw visitors into a space, create a focal point there using red and/or yellow and/or orange.
Another application of color theory can be seen in the use of color to create either unity or contrast. Landscapers may stay within the warm-colors group or the cool-colors group in order to provide unity, be it within one planting bed or throughout the yard. In the latter case, different parts of the yard are thereby tied together to form a harmonious unit.
Alternatively, landscapers may deliberately juxtapose warm colors and cool colors within a planting bed to produce a contrast. An example of a maximum in contrast is yellow and purple. The other pairs that are directly across from each other on the color wheel also afford maximal contrast. Perhaps you've heard such pairs referred to as "complementary colors," which is jargon from color theory. You may well wonder, "If they're complementary, how can they contrast with each other?" But don't be fooled by the terminology: for the purposes of landscape design, what you need to know is that using these pairs provides striking contrast.
Neutrals allow for transition between stronger hues. Neutrals can also be used to soften the effect of loud color schemes or stand on their own in a monochromatic scheme (e.g., all-white gardens).
On Page 3 we move from color theory to some common-sense considerations, followed by links to flower photos, grouped by color....