Combine the current trend of large, open floorplan homes with integrated kitchen, dining and living rooms and add the ongoing popularity of vibrant paint colours, and you can have a problem. Transitioning from one paint colour to another when the wall runs unbroken from the kitchen to the living room can present a challenge. There are several methods for making the colour divide look natural, instead of awkward. Depending on the colours you choose, the rooms can blend together with a subtle change in hue or be dramatically different with bolder colours.
Look for an architectural break in the wall to naturally divide the colours. This could be an archway, doorway or the narrow backsplash wall between the upper and lower cabinets. If there is a natural break, or just a small strip of wall, transitioning from one colour to another at that juncture won't look choppy.
Use a decorative paint trick to create a division between two colours. This can be a checkerboard column of squares, a curved free-form line, zigzags or stripes. Use different shades of the wall colours and lines or shapes that echo other decorative elements in the room.
Paint a single diagonal line instead of a vertical one to divide the colours. Experiment with masking tape on the wall to determine the angle and placement.
Blend the two colours together, as long as the two colours mixed together don't make a third colour (for instance, mixing a red with a green will make muddy brown.) On paper plates, mix the colours and apply them with a sponge or damp rag so they gradually blend from one to another.
Install a decorative column where you want to divide the colours. Look in decorating showrooms and home improvement stores for columns designed to be attached to a wall. Paint or stain it the same colour as the rest of the trim or cabinets.
Keep the ceiling and trim the same colour throughout to maintain a flow and avoid making the rooms look too choppy. Avoid using two very different or complementary colours unless your decor is already fairly bold. Use different shades of the same colour or colours in the same family. If you decide to paint a single vertical line between the two colours from floor to ceiling, find a tall narrow sculpture or decorative screen to place in front of it so it doesn't look too abrupt. Get testers of the colours and paint samples side by side on the wall to make sure they look good. It's hard to predict colour from the little paint swatches. If you can't figure out how to divide a wall without it looking strange, ask yourself how one of the colours would look extended all the way into the other room.