St. Augustine grass seed is not available for purchase. St. Augustine grass is very difficult to grow from seed so it is commonly sold in the form of springs, plugs or sod.
Even in commercial growing operations, farmers propagate St. Augustine grass using sprigs from existing grass because growing it from seed is unreliable and not economically feasible. Without mowing, the grass eventually produces seeds, but the propagation rate from seeds is very low. The grass spreads quickly when using established plants as starters. Local garden stores and national chains, such as Home Depot and Lowe's, sell St. Augustine grass as plugs and sod.