Saint Augustine grass (Stenotaphrum secundatum) grows in tropical areas and is planted in the southern and western United States. It rivals Bermuda grass as the most important grass for tropical and subtropical climates. While it isn't cold-hardy, it performs well in heat and can grow reliably in full sun to part shade. Plant Saint Augustine grass in the spring or fall, since planting in the summer will cause undue stress on the developing grass.
Move any lawn furniture that's on your lawn before planting Saint Augustine grass. Then mow the lawn with a lawn mower, cutting it as short as possible. If you're planting the grass over a bare lawn, skip this step.
Top off any dips in your grade and bare patches with topsoil, to create an even grade. When the grass seeds sprout, your lawn won't have grade issues. If your lawn is even, skip this step.
Rake over any bare patches on your lawn with a rake to loosen the top 1/4 inch of soil. If you're planting Saint Augustine grass over a bare lawn, rake the entire topsoil to loosen the top 1/4 inch.
Sow grass seed over your lawn with a lawn spreader or by hand, applying 16 seeds per inch. Then cover the seed with 1/4 inch of topsoil, to prevent it from blowing away.
Water the soil and grass seed until it becomes damp, but not wet. Keep watering the grass seed daily until your grass grows in.