St. Augustine Grass

What is St. Augustine Grass? (When & How To Grow It)

In Grass Guides, Lawn Care by Jamie

It used to be taken for granted that in the American deep south, if you started a new lawn, you used high maintenance St Augustine. But with other low-maintenance grasses becoming more available, people are questioning this common wisdom. Find out whether St Augustine is the right choice for your lawn.

What Is St Augustine (Stenotaphrum secundatum)?

Genus Stenotaphrum
Zone Warm-Season

USDA 9 – 10

Sun Full Sun to Part Shade
Ideal Soil Sand-silt
pH 5.5 – 7.5
Water Requirement Medium; not drought-tolerant
Nitrogen (lb/1,000 sq ft) 3 – 4
Growth Habit Stolons
Height Mow to 2 – 3 inches
Maintenance High
Wear Medium
Tolerance Good tolerance of heat and salt.

Low tolerance of cold.

Low resistance to insects and disease.

Germination Time N/A (Only available as plugs and sod)

Medium Establishment Rate

St Augustine grass is a pretty popular grass in Florida, Texas, and any region with tropical or subtropical weather as it can handle the heat, humidity, salt, and even part shade. It spreads through stolons to create a thick carpet that helps compete against weeds.

But St Augustine comes with a long roster of problems. It is needy, requiring high amounts of nitrogen and irrigation. It is not drought tolerant, so you will need to irrigate your lawn – and it needs [[twice as much water as Bermuda.

What is St. Augustine Grass

While it can handle moderate amounts of traffic, St Augustine can’t handle backyard games of football and its rough texture will make you think twice about walking across the lawn in your bare feet.

It is highly susceptible to diseases and pests, many of which don’t have effective controls, including: Take-All Root Rot (TARR), St Augustine Decline (SAD), chinch bugs, Brown Patch, Gray Leaf Spot, and Lethal Viral Necrosis. You know that a grass is problematic when it has its own virus named after it.

St Augustine cannot handle cold weather at all, more so than other warm-season grasses. With cold snaps becoming more frequent in some southern regions, it can only be reliably grown in Zones 9 and 10.

Because it grows only by stolons, St Augustine develops thatch more quickly than other grasses and needs to be dethatched regularly. While other lawns can go years without needing dethatching, St Augustine will need it at least once a year.

When establishing a new lawn, your choices are between using plugs and using sod. Seed is not available commercially, and even if it was, it has an unreliable germination. Plugs are the less expensive option. Along with keeping the plugs moist, you will also need to fertilize it more during its first three months.

Lawn care companies and landscapers may push this choice on you as it needs frequent mowing, fertilizing, and care, so they can make a lot of money in maintenance.

In Australia and South Africa, St Augustine is known as Buffalo Grass, not to be confused with the North American native and low-maintenance Buffalo Grass (Buchloe dactyloides).

Overall, whatever advantage St Augustine offers that fits your situation, there’s usually another grass that can better suit your needs with less maintenance.

Pros and Cons of St Augustine

Pros Cons
Tolerates both Full Sun and Part Shade Highly susceptible to pests and diseases
Grows well in high heat and humidity, in regions with subtropical to tropical weather Cannot handle cold temperatures; a cold snap can kill the lawn
Suitable for coastal areas; tolerant of salt Develops thatch much more quickly than other warm-season grasses, requiring annual dethatching
Grows a thick, carpet-like grass that outcompetes weeds Needs a lot of nitrogen and water to survive; not drought-tolerant and not eco-friendly
  Coarse texture and moderate foot traffic makes it unattractive for backyard games and walking barefoot
  Stolons look unattractive when the grass thins to bare spots.

How To Grow St Augustine

Seeding/Overseeding

You won’t be seeding or overseeding a new St Augustine lawn. Because seed germination is so unreliable, the only ways to establish a new lawn is through plugs or sod. Sod will give you an overnight lawn at a higher price, while plugs will take some time to grow, spread, and establish itself into a suitable lawn.

You’ll need 18 plugs to cover 32 square feet. Both need to be fertilized and irrigated more often during the first three months while the grass gets established.

The best time to plant St Augustine is in the spring and summer, when high temperatures are between 80F and 100F.

Mowing

St Augustine does best when mowed to 2 to 3 inches tall, with some experts even advising 3 to 4 inches. Only remove ⅓ of the growth at one time. Any lower than 2 inches and you risk scalping your lawn. And the lower you mow, the more frequently you’ll need to mow. [Consider leaving grass clippings on your lawn (broken up to prevent matting) to help return nitrogen to the soil.

Weeding

A healthy St Augustine lawn is your best defense against weeds, as St Augustine will grow thick enough to shade out weeds. What weeds that do pop up can be easily hand-pulled. Weeds only become a problem when St Augustine thins out.

If you decide to use chemical herbicides, be especially careful with herbicides containing 2,4-D as St Augustine grass is very sensitive to this chemical.

Weeds can also give you valuable information about your soil, as many weeds will only pop up under certain conditions. Clover, for example, loves nitrogen-deficient soil – and since it can store atmospheric nitrogen in its roots, which later decomposes and feeds your lawn, they’re already helping you fix the problem without risking fertilizer burn.

Fertilizing

St Augustine needs a lot of nitrogen to keep happy. If you’re using synthetic fertilizer, you’ll need to reapply every 8 – 10 weeks, starting a few weeks after the grass turns green and after the threat of frost, and ending in November.

Synthetic fertilizer comes with many downsides:

  • They’ll exacerbate pest, disease, and thatch problems.
  • You risk nitrogen burn, harming or even killing grass, if you apply too much.
  • Synthetic chemicals are dangerous to your health, the health of children and pets, and the environment around you.

Organic fertilizers, like compost, reduce the risks of all the above. Because compost supports healthy soil microbiology, your soil then helps your plants fend off pests and disease and help decompose stolons and reduce thatch buildup. It won’t prevent all problems, as St Augustine is particularly prone to all three, but it’ll be an excellent step in the right direction.

To use organic methods:

Watering

Grass Watering

If you’re hoping to keep your water bill down, St Augustine is not the grass for you. It needs regular watering and cannot thrive in a non-irrigated lawn. When establishing a new lawn, you’ll need to keep the plugs or sod moist, which requires frequent, shallow waterings. Once established, St Augustine requires more than an inch of water per week.

Aerating

St Augustine prefers a fairly light and aerated sand-silt soil, so if your lawn is compacted or heavy clay, you’ll need to core aerate. A core aerator will pull out plugs of grass to open more space in the soil. The plugs will decompose quickly.

The best time to core aerate St Augustine grass is in early summer, when the grass is growing rapidly. Aeration causes some stress on the grass, so it’s best to do it when St Augustine can best recover, and only when necessary.

Dethatching

As St Augustine spreads only through stolons, it is more likely than many other warm-season grasses to suffer from excessive thatch. Over-fertilizing contributes to thatch problems; it’s better to underfeed than overfeed. Only dethatch when thatch builds up over ½ inch thick. You may need to dethatch every year.

Frequently Asked Questions

Is Bermuda Or St Augustine Better?

Both Bermuda and St Augustine are warm-season grasses that are high maintenance. St Augustine tolerates more shade than Bermuda, which needs full sun. While they’re both prone to pests and disease, St Augustine is even more prone. Bermuda can handle colder weather and more foot traffic than St Augustine. Bermuda can handle dry spells while St Augustine must be irrigated.

St Augustine is far more expensive to establish a new lawn, although both require a lot of time and money to maintain. The best grass for you depends on your region, your yard, and your needs.

Where Does St Augustine Grass Grow Best?

St Augustine grass grows best in tropical and subtropical regions. In the US, that range is USDA Zone 9 – 10, or Florida and some parts of Texas. It can’t handle much cold weather and has little drought-tolerance, so it loses any advantage in even slightly colder and/or drier regions. There are other grasses that grow as well with fewer problems that can handle the same range or colder.

How Do You Treat St Augustine In The Winter?

St Augustine goes dormant in soil temperatures below 55F. If your soil temperatures remain above 60F, then St Augustine will remain green but grow slowly (it grows vigorously in temperatures above 80F). Avoid fertilizing when St Augustine is dormant or growing slowly as you could end up killing your lawn.

Even when dormant, grass needs some water to survive, so water about 1 inch every 2 weeks, especially during dry winters. Don’t water if soil temperatures drop below 40F, as the ground is frozen, the grass can’t absorb any water anyway, and ice buildup could damage your grass.

About the Author

Jamie

Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.