1- Plant large shrubs along the wall. Look for shrubs that grow at least 5 feet tall and wide. Be sure to allow enough room for the shrubs to grow to their mature size – no ‘poodle-pruning.’ The shrubs will look great while adding texture and color like the ‘Sparky’ Tecoma shrub above. Note: Many people get this wrong by either spacing shrubs too closely together or excessively pruning them.
2- Paint your wall a colorful shade of blue, purple, red, or even yellow. This is a common design style in the Southwest and several of my clients have employed this design strategy. You can add plants like shrubs or cacti along the painted wall for added interest. Garden art also looks great on painted walls and is a useful option when there isn't enough room for plants to grow.
3- Cover the wall with pine wood planks, arranged horizontally, and stain them an attractive color. The planks of wood can be attached to metal stakes along the back. This creates a very modern look with an organic element. A welcome bonus is a wood decreases the radiated heat that comes off of block walls in summer.