Everything About St. Augustine Grass
A gardener planning to have St. Augustine grass as a lawn grass in their garden should be prepared for coarse-textured grass that is not very traffic tolerant.
However, as a trade-off, they will get one of the darkest green and thickest lawns that they would be proud of.
Published: October 21, 2022.
What is St. Augustine Grass?
St. Augustine grass (Stenotaphrum secundatum) is a warm-season grass, i.e., it thrives when temperatures are between 75°F and 90°F. It’s a perennial grass belonging to the family Poaceae.
This dark green grass has broad, flat blades, and its color lasts longer during a drought than other warm-season grasses like Zoysia grass or Bermuda grass which go dormant during droughts. Its color is believed to be the darkest green.
It has a rough texture and spreads by above-ground stems called stolons or more commonly known as runners. It’s popular mainly because it forms a thick, carpet-like layer of the lawn. In nature, it occurs in marshes and lagoons, on shorelines, and in any place where there is a good level of moisture.
St. Augustine Grass has a relatively low cold tolerance, and hence the grower needs to be living in a warmer climate. It can grow in a wide variety of soil types, including sandy soils and a variety of cultural conditions, barring a dark shade. The soil pH should be between 5.0 and 8.5.
St. Augustine Grass can be only grown from sprigs, sod, or plugs. It doesn’t produce enough seeds to be sold commercially. Once it is cultivated, it can self-propagate.
St. Augustine Grass Growing Zones
St. Augustine grass thrives well in USDA plant hardiness zones 8 to 10.
It occurs in most Mediterranean and Caribbean areas and thrives well in tropical climates. It grows well on both sides of the Atlantic Ocean, including most parts of the southeastern United States, Texas, Mexico, and South and Central America.
According to the University of Florida, St. Augustine is the most commonly used lawn grass in Florida. The species is also popular along the Gulf Coast.
Cultivars of St. Augustine Grass
There are several cultivars of St. Augustine grass. These include:
Floratine: Released in 1959, Floratine has a finer texture and darker color. It withstands lower temperatures and requires less mowing.
Floratam: Developed during an educational partnership between the Texas A&M University and the University of Florida and released in 1973, Floratam has good resistance to a viral infection called St. Augustine decline (SAD) and to chinch bugs too, but is not very cold- or shade-tolerant.
Captiva: Developed by the University of Florida and released in 2007, Captiva is known for its resistance to the southern chinch bug and short height, which needs less mowing.
Seville: Seville was released in 1980. It’s similar to ‘Floratam’, but has a finer texture.
Sapphire: Chosen from Australia for its dark blue-green blades, purple stolons, and fast lateral growth, Sapphire was released in 2004.
Raleigh: Raleigh can withstand cold but is susceptible to insects and diseases. It was released in 1980.
Palmetto: This is a smaller grass, lighter green in color which was released in 1959.
Variegatum: Variegatum is an evergreen creeping grass with white striped blades. The Royal Horticulture Society gave it the prestigious Award of Garden Merit in 1993.
Texas Common: Texas Common is less popular because it’s susceptible to the incurable SAD virus.
Sir Walter: Sir Walter was released in 1996 for Australian conditions with qualities such as heat- and drought tolerance.
For more information about this topic, feel free to check our St. Augustine Grass Types article.
When to Plant St. Augustine Grass?
St. Augustine grass should be planted in the warm spring and summer months when temperatures rise from 80°F to 100°F.
The sprigs, sods, or plugs of this grass should be planted in full sun at least 90 days before the area’s first expected fall frost so as to give it sufficient time to establish.
How to Grow St. Augustine Grass?
There are several methods of growing St. Augustine grass, including growing with sprigs, plugs, sods, or seeds.
Growing with Sprigs
Growing St. Augustine grass with sprigs, also known as stolons, is one of the quickest ways to spread a St. Augustine lawn. It’s also a cheaper alternative to growing this grass with sod. Since St. Augustine grass naturally spreads through stolons or sprigs, one can take advantage of it to grow a new lawn or fill in thinned spots in an existing lawn.
Although a sprigged lawn takes a bit longer to establish than a sodded lawn, one can have a full lawn much faster with sprigging than growing grass from seed.
Separating the Sod into Individual Sprigs
The gardener should first separate the St. Augustine sod with a knife or by hand into individual sprigs, each having a few roots. 1 sq. yard of sod will yield around 500 sprigs.
Making Slits for Planting
Now the gardener should insert the spade’s blade into the soil around 2 inches deep and at a 45° angle. Then they should take the blade out without turning over the soil.
Now they should slip the root end of the sprigs in the slit made by the spade’s blade. The other end of the sprig should be left sticking out of the soil.
They should now seal the slit by stepping on the ground above the sprig.
There are 2 opinions about spacing the sprigs. According to the Oregon State University, sprigs should be planted 10 to 20 inches apart for the best coverage, whereas according to the University of Georgia, the spacing should be 6 to 8 inches.
When all the sprigs are planted, the gardener should water them. They should give around ½ inch of water every day when there is no rain until new growth appears on the sprigs. After that, they should give 1 inch of water twice a week.
Growing with Plugs
Measuring the Yard
It’s a good idea to know the dimensions of one’s yard so as to purchase the right amount of St. Augustine plugs. A pack of 18 plugs can cover around 32 sq. feet.
Preparing the Soil
If one wants to replace an existing lawn, they can rent a sod-cutter to remove the old sod and other vegetation. Next, they should apply a non-selective herbicide 2 weeks before planting to kill weeds. They should use a product that won’t leave a residue that might harm the newly planted St. Augustine grass.
If the gardener has only a few weeds here and there, they can hand-pull them. But they should make sure that they pull out the entire root system. Or else, the weeds will germinate and grow back while the new plugs are still establishing.
Before planting, the grower should water the area thoroughly in order to make the soil more malleable and give the new St. Augustine grass immediate moisture. The gardener should make sure that the water is soaked in the soil and doesn’t remain on the surface. They should also make sure the water is fully absorbed in the soil which can take several minutes.
Now the gardener should dig holes in a diagonal planting pattern to form a diamond of each group of 4 holes. There should be a 12-inch space between the holes so there would be 15-inch space between holes across the center of each diamond.
The holes should have a bit larger diameter but the same depth as that of the plug’s root ball. Grass plugging tools can be bought or rented online or from one’s local hardware store. This tool is useful to make perfectly plug-sized holes with a lot less effort.
Placing the Plugs
Now the grower should place one plug firmly into each hole and make sure it levels with the surrounding soil. If they’re placed too deep, the gardener can add a little soil back into the hole to fill it.
Now the gardener should water the plugs daily or as required until they are firmly rooted and start spreading. This will usually take around 7 to 14 days as the roots establish. After that, they should water weekly unless the lawn gets a generous rainfall.
Monitoring Pests and Diseases
Newly planted St. Augustine grass is in need of protection while getting established. This is the time when both roots and the lawn are susceptible to diseases and pests. Gardeners should watch their lawn closely. If they observe any mildew or brown spots forming, they should contact their local extension agency for treatment options.
Growing with Sods
The gardener should first prepare the soil by applying a glyphosate weedkiller over the planting area. They should follow the instructions on the product.
The product should be applied on a dry day that shouldn’t have much wind. Spraying the weed killer before tilling offers an estimate of competitors that can destroy the St. Augustine grass.
Growers should wear protective gear such as long-sleeved shirts, gloves, and a facemask. Also, they should keep pets and other people away until they’re finished.
Now the glyphosate should be left undisturbed and allowed to soak for 2 weeks. It won’t poison the soil so the grower should not worry.
Although it’s not necessary, the grower can spread a tarp over the soil to make sure nothing else grows there.
It’s also not necessary to remove the old plant matter as when the gardener will till the soil later, it will serve as a natural fertilizer.
Tilling the Ground
Now the grower should till the ground to a depth of 4 to 6 inches. If they wish to plant the sod in a small area, they can use a shovel to turn over the soil.
For larger areas, they can use a rototiller so as to till the ground quickly. They should set the rototiller to the right depth setting, and then push it back and forth over the whole area at least once. They can even rent a rototiller and save money.
Raking the Ground
After the ground has been tilled, the grower should take a rake and remove any debris with it that the tilling has dug out, such as old roots and rocks. They should also brush the soil into any holes they find. They should make the ground as flat as they can for the St. Augustine grass lawn.
Planting the Sod
Now the gardener should lay a line of sod along the border of the planting area. They can get sod in rolls as well as smaller squares. Both of these are planted in the same way. They can begin from one side of the yard and place squares or unfurl the rolls till they reach the other side of the yard.
The grower should continue laying the sod until they cover the entire yard. They should make sure they place the sod as close together as they can.
The grower should make sure they don’t walk over the sod they’ve already laid. Instead, they should kneel or walk on plywood.
They should cut the excess sod (that’s coming out of the planting area) with a hook-billed knife or sharp shovel. This way they should also cut apart sod around curbs, planting beds, and other curves.
After laying the sod completely, the grower should immediately water it up to 1 inch using sprinklers or a hose. They should water sufficiently to dampen the upper 1 inch of soil. This will help the grass settle in the ground. However, overwatering should be avoided. Also, they should make sure the water doesn’t pool on top of the sod or run off of it.
The grower should water the lawn every day for 3 weeks. For the 1st week, they should give ½ to ¼ inch water to the lawn and should make sure the top 1 inch of the soil remains moist. After that, they should water the lawn often until it’s fully established.
After the 1st week or so, they should give ½ to ¼ inch water 2 to 3 times a week. The grass should finish rooting in 3 to 4 weeks.
They should check the depth of water by digging in the wet soil away from the planted grass or just by guessing. They should make sure the water never lingers on the soil or run off the grass.
They need not water the lawn on rainy days.
Avoiding Walking on the Grass
One should avoid walking on the grass until it’s fully grown. The grass should be left alone at least for a month after planting.
How to Take Care of St. Augustine Grass
The grower should water their St. Augustine Grass deeply as the grass loves moisture. They should understand that when footprints are visible after walking in the grass or when the leaf blades wilt and go blue-gray in color, it indicates that the grass needs irrigation.
However, St. Augustine Grass doesn’t need a lot of water but needs it consistently. So, the grower should keep the grass wet.
They should not let the grass dry out. Some growers cut back on water when it’s raining, but won’t supply it again when it stops raining. This should be avoided.
When it comes to fertilizers, one should conduct a soil test before applying any nitrogen. Growers should not apply fertilizers too early in the growing season, as during this time the root system isn’t fully developed and so cannot absorb the nutrients.
But on the other hand, they should not even apply fertilizers too late as growth subsides then.
Experts recommend applying only 4-5 pounds of nitrogen per 1,000 square feet of established St. Augustine Grass lawn per year. Excessive fertilization can cause diseases and thatch problems.
St. Augustine Grass is a grass that has to deal with thatch development. Thatch problem indicates either excessive watering or excessive fertilizers. If the thickness of thatch layer is more than 1 inch, the grower can remove it by verticutting or vertical mowing.
However, they should do it only when the grass is in an active growth period so it’s able to repair the damage before the following dormancy period.
The height of St. Augustine Grass should ideally be kept to 3.5 to 4 inches. But the taller, the better. It should be kept tall and wet, and the height should be at least 3 inches. If the grower mows it at 4 to 5 inches, the grass will become a lot hardier, i.e. it will recover from stress a lot quicker and it will be greener because there will be more leaf surface.
As such weeds are minor problems to St. Augustine grass since if the turf is healthy, it chokes weeds. Also, pre-emergence herbicides are useful where broadleaf weeds are a threat.
Treating Common Problems
Experts say that although fungal diseases are common in St. Augustine Grass, they are not lethal i.e. they’re mostly cosmetic problems. The grower may have to deal with these problems, but most people won’t even notice them in St. Augustine Grass. Since this grass is taller, darker, coarser, and hardier, it covers most of the problems. However, it’s also susceptible to a more dangerous infestation named chinch bugs that are lethal.
Brown patch is commonly seen in St. Augustine Grass. It creates large circles on the lawn. However, it doesn’t kill. It only destroys the top leaves. But those leaves will be quickly replaced by new ones and as the grass recovers. However, when the disease appears, it looks very ugly.
Dollar spot also commonly attacks St. Augustine Grass and appears as round circles of 1” to 4” in diameter. The grass in these spots is discolored. They may remain restricted to only some areas of the lawn or may join together to form larger, irregular shapes.
If one examines the discolored grass in these spots, one can see small legions on the leaves often of an hourglass shape.
Also, one can see structures like fine white spider webs across the affected area on cooler mornings. But they will disappear once the dew has subsided and the temperature rises with the day. These web-like structures are actually a byproduct of the fungal disease i.e. dollar spot.
Dollar spot is commonly caused due to a lack of nutrients in the soil and excess moisture. This means that wrong watering practices and lack of fertilizers are the main culprits. In addition, any other factors that weaken the lawn can also support the outbreak.
Although dollar spot can be treated with fungicides, it’s not really necessary. The key to cure dollar spot is good lawn care.
One should first start a good year-round fertilizer application regimen. Nitrogen deficiency can be a major cause; hence a fertilizer high in nitrogen should be used.
Regular mowing also helps to keep excess thatch away, as it promotes the disease. Regular lawn aeration and de-thatching will also help in keeping dollar spot away.
One should water their St. Augustine lawn only in the mornings and excess watering should be avoided as far as possible. It’s a good idea to water less often, but to apply more water every time. This will cause the roots to grow deeper in the ground, making the turf more drought-tolerant.
Instead of treating fungal lawn diseases with fungicides, one can try to make the lawn as healthy as possible in the above ways and create an environment around the lawn that is favorable to lawn health and hostile to diseases at the same time.
If all these efforts fail and the dollar spot remains prevalent, then the gardener should consider applying a fungicide.
Gray Leaf Spot
Gray leaf spot is a fungal disease that weakens the sod and ruins the lawn’s appearance. Applying fungicides in the early season can usually control this disease before it becomes a serious problem.
As mentioned earlier, chinch bugs are dangerous to St. Augustine grass. The lawn can just go dead with the invasion and there is no recovery.
However, there is good news – chinch bugs can be easily controlled because they have no wings and have slow movements which prevent them from spreading too far. Chinch bugs are favorable to thatch development; hence correct cultural controls can keep them away.
Mistakes to Avoid
To Use as a Wear-tolerant Grass: If one wants a wear tolerant grass for their lawn, they should understand that St. Augustine is not for them. It cannot withstand repeated foot traffic.
Lawn Leveling: Many homeowners make the great mistake of cutting St. Augustine grass to the level of the shortest grass on their lawn. Cutting St. Augustine to less than 3 inches will make the grass die within a year.
Trimming: Another same type of mistake homeowners make is to trim St. Augustine grass near the edges of surfaces like driveways and sidewalks. This also causes the death of the grass being exposed to the hot sun as well as reflective heat and absorbed heat from the concrete surfaces.
St. Augustine grass forms one of the greenest, thickest, and most spectacular lawns in one’s garden. Hence if the gardener is living in a warm climate, they should essentially consider growing a St. Augustine lawn.