Matching vertical blinds give the illusion that there is no window in the room when they are closed. To perfectly match the blinds to the paint color of the walls, it is necessary to have the vertical blinds custom made and you will need to provide paint chips of the existing wall color to the designer. This can be costly, particularly if the window in the room is large or if you are using vertical blinds to cover a patio door.
Contrasting blinds typically do not need to be custom made and are a more economical option because there are many off-rack colors that can be used. A contrasting blind color should be the opposite of the wall color on the color wheel. For example, if the wall color is a pale yellow, the appropriate contrasting color would be light purple. You can find color wheels at most home design stores or simply look at one online.
Complementary blind colors need to come from the same color family as the wall color. For example, if the wall color is ivory, this is a warm color group and is considered to be a neutral. This means that the blind color should also come from the warm color group and be in a neutral shade. If the walls are blue, a complementary blind color would also be in this same spectrum of color, either in a lighter or darker shade of blue.
You can also use vertical blinds to create an accent color in the room. This technique works especially well if the vertical blinds are covering a large area of the wall. If the wall is white, you can have a bold red color for your blinds and then echo this color throughout the room with throw pillows and red accessories. The concept for this technique is, instead of painting an accent wall, you simply use the blinds to serve as that bright pop of color in the room.