Painting this rendered wall?

[seanoge]

My wife has a Herb garden and the Blocks are concrete. They were rendered and now she wants to paint the wall. Will it be a waste of time as water will always soak through from the soil?

 

[JohnD]

you can do it with masonry paint, but efflorescence/limescale will come through and will look very bad on a dark colour.

 

[Robbie uk]

should have lined the inside with plastic first. You would still get damp travelling upwards though.