As is the case with any grass, before laying down St. Augustine grass seed, you need to prepare your lawn. Using a rake or a rototiller, upturn the top 2 inches of soil and remove any weeds, rocks, and sticks. Using the rake, break up the clumps of dirt and smooth the ground until it is level and even.
St. Augustine grass is not usually sold in seed form as it has trouble germinating and establishing itself in this form. Thus, most St. Augustine grass seed you will find in stores is mixed with other types of grass seed to help spread and establish.
Before laying the seed down, cover your lawn with 1-2 inches of natural, nitrogen-rich fertilizer. You can also apply a non-selective herbicide and let that sit for at least 2 weeks before laying down the fertilizer. St. Augustine grass seed requires a lot of fertilizer to grow, so you should not skip this step.
Next, start to apply the seed using a broadcast spreader. After covering your yard, use the rake to mix the seed with the soil. You can also mix in a bit of sand or topsoil to make the soil more even at this point.
Once you have the seed laid down, you need to water your lawn with around 3-4 inches of water. You do not want to overwater your lawn as this can drown the seeds and erode the soil. You want the soil to absorb the water fully and become moist and pliable. If you start to see puddles forming, then you are adding too much water.
Continue watering your lawn daily for the next two weeks until the roots settle and the grass sprouts. You can then reduce watering to twice a week for the next week unless there is rainfall. You should also take this time to screen your lawn for pests and other critters. St. Augustine grass is notorious for picking up pests and lawn diseases, which can ruin all of your hard work up to this point. You can tell if your grass is contracting a lawn disease if you see any brown and mildew spots starting to form.
Wait until the grass has grown to 3 inches before mowing it for the first time. You should sleep your lawn at about 1-2 inches tall.
Sod is usually the method of choice for installing St. Augustine grass. Prepare the soil with a till and apply fertilizer. When you start to lay the sod pallets, minimize any seams, and make sure the edges do not overlap. Use a lawn roller to smooth out any bumps and make sure there are no trapped air pockets.
After laying the sod, water it with 3 inches of water and continue to water it daily for 2 weeks. After two weeks have passed, reduce watering to once a week unless there is rain. You can also mow it for the first time, but make sure that you remove any grass clippings. Sod has thatch built-in so the clippings can make the thatch layer too thick. You should mow frequently enough that you never have to take off more than ⅓”.
Although it is tough to get it to take root, St. Augustine grass spreads rapidly once it gets established. It will take about 2 weeks for St. Augustine grass to start spreading. You can improve this spread with regular treatments of fertilizer and keeping your lawn properly mowed.
St. Augustine is a warm-season grass so it typically grows better in hotter climates that receive a lot of sunlight. That is why it is popular in the Southeast US. The best time to plant St. Augustine grass seed is during the beginning of the warm season, so the late spring after the last frost of the year has passed. If you plant it too late in the year, it will not establish itself before the onset of the colder months.