I am building raised gardens with concrete block. I'm not really excited about the naked concrete looks in my garden so I was thinking about putting a concrete stain on the outside of the blocks. Wife would like a celery or sage green color so it will blend in with the garden. I was wondering what color would be best. I think a darker color would absorb the sun rays in the cool early spring to warm the soil quicker. Anybody ever done something like this before? Any suggestions or ideas?