Tall Fescue vs. St. Augustine (Turf Comparison)

If you live in a transition zone and are trying to decide whether tall fescue, a cool-season grass, or St. Augustine, a warm-season grass, would be better for your specific situation, you are in the right place. Below you can find all of the details you should consider before settling on either of these grass types, from appearance and maintenance needs to durability and cost.

Comparing Tall Fescue vs. St. Augustine

The main points to pay attention to when you’re comparing St. Augustine vs tall fescue are temperature and soil type. At its most basic, St. Augustine does well in poor, well-drained soil and cannot tolerate long periods of damp. It also can’t handle a freezing winter. Tall fescue, on the other hand, works well in yards with lots of shade and clay soils that never quite seem to dry out.

Appearance of Tall Fescue and St. Augustine

There is a single, primary difference between tall fescue and St. Augustine when it comes to appearance. That difference is growth habit or angle. Tall fescue grows straight up unless it’s trained to angle in a certain direction. St. Augustine grows out and to the side in a somewhat flat pattern. It can be trained, with effort and the right tools, to lay over in a given direction but this isn’t commonly done.

Beyond growth habits, tall fescue and St. Augustine do look similar. Both have medium to dark green blades, broad blade types, and a coarse blade texture. However, tall fescue blades are a little thicker than St. Augustine. The blades of St. Augustine can become so paper-thin, when under-watered, that they can even cause small cuts similar to paper cuts when handled.

Best Uses for Tall Fescue Grass vs St. Augustine

St. Augustine grass should be used in a warm, sunny, well-drained yard to create an even, low-maintenance, and low-moisture lawn. St. Augustine is not great for the lawns of homes with large pets, pets that dig, or hobbies that may place wear and tear on the lawn as St. Augustine can be slow to repair.

Tall fescue will be slightly higher maintenance than St. Augustine but no higher than the average for any lawn. It needs cooler temperatures, such as those found in USDA zones 5b through 6b. Tall fescue has greater durability than St. Augustine and can handle higher traffic areas and activities. It repairs itself faster if damaged. Tall fescue also works better in shady yards than most grass types, St. Augustine included.

Soil Types and pH Needs of Tall Fescue vs. Needs of St. Augustine

The pH need of tall fescue is in the 5.5 to 7.5 range, making tall fescue much more adaptable than St. Augustine with its 6 to 7 range. Tall fescue can even adapt to slight variation outside of this range with little notable change in appearance or growth. St. Augustine’s growth will slow and color may fade if the soil pH is over 7. A pH of less than 6 may cause the roots of St. Augustine to die back or struggle to grow.

Tall fescue likes clay soils or loamy soils that do well at retaining moisture. It can hold onto slopes very well and produces deep roots. St. Augustine turf prefers sandy, well-drained soil and can stay in place well if not exposed to heavy rain or high traffic.

Water Needs for Tall Fescue Lawns vs. Water Needs for St. Augustine Lawns

The minimum water requirement for both tall fescue and St. Augustine are the same. St. Augustine, however, will not handle excess water well. It will take up more than it needs and disperse it. This may be because it handles standing water or muddy soil poorly and actively works to prevent this situation. However, if you have plants nearby that could use this extra water, St. Augustine could work as an antagonist to their needs.

Tall fescue will take up just what it needs and no more, making it a bit more “water smart” than St. Augustine. It also grows a bit taller, creating more shade around the roots and soil. This slows evaporation even in the hottest weather and can help reduce the need for irrigation.

Sun, Shade, and Temperature Requirements for Tall Fescue vs St. Augustine

St. Augustine does best with full sun and will not tolerate even partial shade for more than 2 hours a day. In areas that are overtaken by shade, a St. Augustine lawn will noticeably thin, even if otherwise taken care of perfectly. St. Augustine will not tolerate freezing and will go dormant at just 55F. Once temperatures reach below 40F, St. Augustine may be in danger of dying back. If the lawn freezes, the St. Augustine grass may die in patches or entirely.

Tall fescue does not die back like St. Augustine in the cold or the shade. Tall fescue can thrive in everything but total, deep shade. It does not thin or develop shallow roots in dappled shade or any area that is in full shade for up to 6 hours a day.

Tall fescue can survive frost and even a few weeks of freezing, provided traffic on the lawn is reduced while it is dormant and frozen. St. Augustine begins to go dormant below 50F and above 90F. In weather hotter than 90F and in water restricted or drought conditions, tall fescue may appear to “rust” or develop burnt ends. Though not attractive, this does not indicate a plant that is dying and the grass should recover fully should regular moisture levels be restored.

Durability of Tall Fescue vs St. Augustine Lawns

In a contest of durability measured through traffic on the lawn, tall fescue would be the clear winner. Tall fescue handles traffic, as well as being cut or crushed, much better than St. Augustine. It also has a faster recovery time and is less expensive, in terms of time and money, if any portion of the lawn needs to be replaced.

St. Augustine is expensive to replace and will recover slowly if damaged. It also has a shallow root system compared to tall fescue, allowing damage to occur more easily. St. Augustine is meant for low-traffic areas. This is one of the main trade-offs for how low-maintenance this variety is.

Common Pests and Diseases for Tall Fescue or St. Augustine

Tall fescue and St. Augustine both have their share of natural threats, beyond human and pet traffic. For tall fescue, the regular threats of digging animals, ants, and even webworms are there but the damage potential is low. Crown or leaf rust and fungus such as fairy rings are a real threat to the health of your tall fescue lawn.

St. Augustine is in a similar situation with the common pests but it has 3 main pests and diseases that you’ll need to remain vigilant about. The first is chinch bugs. While these bugs don’t seem to bother any other grass type, they can devastate a St. Augustine lawn. Fungal diseases like brown patch and root rot can also be a problem if you get more rain than expected or end up with drainage issues.

Mowing Needs of Tall Fescue vs. Mowing Needs of St. Augustine

St. Augustine is known to be a low-maintenance grass type for good reason. This grass type grows slowly all year long. It’s also low growing so when it does get “tall” it won’t look like it unless you get up close. Most of the year you will get by with mowing every 2 weeks or even less. In early summer you may need to mow weekly for as many as 6 weeks. The ideal mowing height for St. Augustine is 2” to 2.5”.

Tall fescue requires average mowing and maintenance with an ideal mowing height of 2.5” to 3” or a little higher in weather over 90F. In the better growing periods for tall fescue, typically late spring and early fall, you will need to mow weekly. After these periods are over, you should get by with mowing every 10 to 14 days.

Are There Better Strains of Tall Fescue or St. Augustine?

There are few available types of tall fescue, though there are other types of fescue to consider with similar growth patterns but some alternate characteristics. The most popular among these types is fine fescue, with red and chewing fescues also being viable lawn options.

St. Augustine grass does offer a few options for strong varieties that help you deal with some of its weaknesses. “Captiva” St. Augustine is less susceptible to chinch bugs, for example. If you’re looking to cultivate a lawn that is low-maintenance but also impressive, you may want to consider “Variegatum” St. Augustine for its variegated blades.

Tall Fescue vs. St. Augustine: Cost

What is the cost difference between tall fescue and St. Augustine? The reality is, that there is a big difference in the cost between planting tall fescue and planting St. Augustine. At the most basic level, this difference is due to the means and methods of growing these types of grass. While tall fescue can easily be grown from seed, St. Augustine must be grown from plugs or cuttings or sod must be placed. At a minimum, at the time of this writing, this would mean about $300 total in seed costs for tall fescue and $700 for St. Augustine plugs to cover an average-sized lawn of about 10,000 square feet or ¼ acre.

Can You Mix St. Augustine and Tall Fescue?

St. Augustine and tall fescue, like most grasses, should not be mixed. Mixing grass types rarely provides benefit and frequently results in both grass types competing against each other with whichever type is best suited to your climate winning, but at the cost of a sparse-looking lawn for several years.

Specifically, St. Augustine and tall fescue should not be mixed as these are two very different grass types suited to drastically different situations. While tall fescue is a versatile grass type, it’s still a cool-season grass while St. Augustine is a warm-season grass type. The appearance of a tall fescue and St. Augustine lawn is also messy as the growth of the grass follows a different pattern.

The Best-Case Scenario for a Tall Fescue or St. Augustine Lawn

The best-case scenario for a tall fescue lawn is high traffic, mixed sun and shade, and a cooler climate with average to heavy rainfall. Maintenance will be about average or a little less. Clay soil is preferred and the yard can be sloped, flat, or a mix of both.

The best-case scenario for a St. Augustine lawn would be low traffic with well-drained, sandy soil. Sun and hot weather are preferred while any zone with a long or freezing winter should avoid this grass type. St. Augustine is a true warm-season grass. Maintenance will be low as this is a slow-growing grass type with a low-growing habit.

I’ve put the main points of comparison between the two in the table below.

Grass Type	Tall Fescue	St. Augustine Grass
Appearance	Dark Green with Coarse, Broad Blades	Low Growing with Broad, Dark Green, Thin, Coarse Blades
Popular Uses	High Traffic Areas and Yards with Mostly Shade	Low Traffic Lawns in Warm, Sunny ClimatesGolf Courses and Athletic Fields, Roadsides
Ideal Soil Type and pH	Rich and Clay Soil is Ideal - 5.5 to 7.5 Ideal pH	Well-Drained, Poor, and Sandy Soil is Ideal – 6 to 7 Ideal pH
Water Requirements	1” of Water Per Week – Average Overall Water Consumption	1” of Water Per Week – Average Overall Water Consumption
Sun/Shade/Temperature Needs	Shade Preferred/Dormant at 50F and Above 90F	Full Sun Preferred, Can Tolerate Part Sun – Dormant at 55F
Durability	High Durability, Fast Recovery	Mediocre Durability and Damage Recovery
Pests and Diseases	Fungus, Leaf Rust – Webworms, Thrips, Ants, Grubs	Beetles, Mole Crickets, Grubs, Nematodes, Chinch Bugs – Fungal Disease – Brown Patch – Root Rot
Mowing Needs	Should Be Mown to 2” Height or 3”+ If Sunny and Hot – Grows Best in Cool Weather	Mow to a 2” to 2.5” Height – Grows Fastest in Early Summer