Color depends on the light source (at night, sodium vapor streetlights, fluorescent, incandescent), and the reflection characteristics of the surface. Perceived color also depends on how the eye and brain process the light coming into the eye, and apparent color changes with influences of the color of surrounding objects.

Also, the perception of color (which may vary from person to person) changes in low-light conditions. In good light conditions, the human eye distinguishes color with three receptor types (cones) with peak sensitivities in the red, green and blue. They are not sensitive enough to provide much useful vision at night (low light). There is a separate set of receptors (rods) with much higher light sensitivity that come into play at low light (night) but they do not give good color information. There is only one set of these in the human eye with a peak response in green.

Also the eye and brain try to adjust the color corrects for the color of the light shining on it and what it deduces the color should be. That is why grass still looks green even when you see it under the red light of sunset.