 The stadium's grass was replaced with AstroTurf in 1970, in part because St. Louis' notoriously hot summers made it difficult to keep the grass alive.The Cardinals retained the traditional dirt skin infield for eight seasons, then converted to sliding pits when the surface was replaced for the 1978 baseball season.With artificial turf, the playing conditions at Busch Stadium were among the hottest in baseball, with temperatures well above the local official readings.