I used oak barrels cut in half filled with dirt then potting soil,lots of flowers. Positioning them front of bays and entry. Biggest draw back was over spray from bays killed them about mid summer, attendant employee would spray them off during day. Once in while kid would pull flowers to give to mother washing in bay. Made deal with flower shop to plant and replace as needed, other positive note car wash would be featured front page of newspaper .Fall season , replaced with corn stalks and place goose and duck decoys , I would wire them down. After 15 years got tired of the hassle and quit,not sure if customers noticed.