My raised bed garden also uses a lot of white, both in variegated foliage and flowers. If it's too hot to sit in the blazing sun, at dusk, when the sun drops below the horizon, it is a cool and comfortable place to sip coffee and watch the white take on an almost unearthly glow. Color me peaceful. But there is another reason besides mood and temperature to be careful with color. Color also alters our perception of space.
Cool colors recede, warm colors jump forward.
A garden of misty blues and lavender appear to fade off into the horizon, and can make a small space seem roomier. The same area, planted in hot reds, could make you feel claustrophobic. On the other hand, those same reds and bright yellows will help to brighten a shady corner where subtler pastels would fade into oblivion. Hot colors are wonderful if yours is a garden you will view more often from a distance than from close-up. Use cool colors in that situation and you'll wonder where the garden went.