Every couple of years we power wash the planter blocks. They get kind of grubby as the tops build up with dirt and bird crap. It’s not hard work, just a lot of it, and it usually takes the day to do it. I also try to do it when it’s nice and hot out as the spray helps keep me cool.
First thing I do is to remove all of the top blocks and lay them in the grass. Then I go around and clean all the tops. Next I stand them up on the backside so I can wash the faces. Then I put them all back on the planter. Lastly, I wash the tops of the second and third row that are showing.
The reason I remove the bricks is that when the spray from the high pressure nozzle hits the dirt in the planter, it blasts the side of the house and windows with dirt and mud, and now I have to power wash the house too. So I pull the top layer off. Here’s a short video to show the process.