Thanks for the hard question, Foxy Lady.
I thought this was a gardening discussion, not Home Depot! LOL
Really it is pretty hard to get stains out of concrete. You might consider staining the stain. There are products at Home Depot, of course, that literally absorb into the concrete and therefore don't flake off and need to be repainted like real paint. We powerwashed the floor of our greenhouse retail shop and got it as clean as possible and then added 2 coats of a sandy colored stain with a roller and it looks damn good. I also stenciled a little rug onto the center section. Some of the stains are opaque and some are more solid, but they work very well, indoors or outdoors. GL Bernice.