Blade width, growth habit, and shade tolerance separate these two common lawn grasses in southern regions. When you are trying to decide between tall fescue vs st augustine, you need to look at your specific yard conditions and how much work you want to put in. Both grasses can look great, but they thrive under very different circumstances.
This guide will break down the key differences so you can make the right call for your lawn. We will look at appearance, water needs, sun requirements, and maintenance levels.
Tall Fescue Vs St Augustine: The Main Differences
Let’s get right to the point. These grasses are fundamentally different in how they grow and what they need. Tall fescue is a bunch-type grass, while St. Augustine spreads by stolons (above-ground runners). This single fact drives most of the other differences.
Here is a quick breakdown of the primary contrasts:
- Blade Width: Tall fescue has a medium to coarse blade, but it is noticeably narrower than St. Augustine. St. Augustine has a very wide, coarse blade that feels thick underfoot.
- Growth Habit: Fescue grows in clumps and does not spread. St. Augustine creeps and fills in densely, creating a thick mat.
- Shade Tolerance: St. Augustine handles shade better than tall fescue, though both need some sun.
- Traffic Tolerance: Tall fescue handles foot traffic much better than St. Augustine, which can get damaged easily.
- Climate: Tall fescue is a cool-season grass that can handle transition zones. St. Augustine is a warm-season grass that needs heat.
Blade Width And Texture
You can tell these grasses apart just by looking down. Tall fescue blades are about 1/4 inch wide. They are somewhat stiff and have a slight shine on the underside. The texture is often described as “coarse” but it is still finer than St. Augustine.
St. Augustine grass has a blade that is almost 1/3 inch wide. It is very coarse and creates a thick, carpet-like feel. If you walk on it barefoot, you will feel the difference immediately. St. Augustine feels more substantial and dense.
For a finer looking lawn, tall fescue is usually the better choice. However, some people prefer the bold, tropical look of St. Augustine.
Growth Habits And Spreading
This is the most critical difference for maintenance. Tall fescue is a bunch-type grass. It germinates from seed and grows in vertical clumps. It does not send out runners. To fill in bare spots, you must overseed. It will not repair itself.
St. Augustine is a spreading grass. It sends out above-ground stems called stolons. These runners take root and create new plants. This means it can fill in thin areas on its own, but it also means it can invade flower beds and sidewalks. You will need edging to keep it in check.
Because of this growth habit, St. Augustine is usually installed as sod or plugs. It is very difficult to grow from seed. Tall fescue is almost always seeded.
Shade Tolerance And Sun Requirements
Sunlight is a major deciding factor. St. Augustine is generally considered the more shade-tolerant of the two. It can survive with about 4 to 5 hours of direct sun per day. Some cultivars like ‘Palmetto’ or ‘Seville’ handle shade even better.
Tall fescue needs more sun. It prefers at least 6 hours of direct sunlight. While some newer cultivars have improved shade tolerance, they still struggle in deep shade. If you have a yard with heavy tree cover, St. Augustine is often the safer bet.
However, remember that no grass thrives in dense, full shade. You may need to trim tree limbs to let in more light regardless of which grass you choose.
Water Needs And Drought Tolerance
Water is a huge factor in the South. Tall fescue has a deep root system that can reach 2 to 3 feet down. This helps it survive dry periods. However, it will go dormant (turn brown) during extreme heat and drought unless you water it regularly.
St. Augustine has a shallower root system, usually only 6 to 12 inches deep. This makes it less drought-tolerant. It needs more frequent watering to stay green. During hot, dry summers, St. Augustine will show stress quickly if it does not get enough water.
Here is a simple comparison for watering:
- Tall Fescue: Needs about 1 to 1.25 inches of water per week. Deep, infrequent watering is best.
- St. Augustine: Needs about 1.5 inches of water per week. More frequent watering is needed because of the shallow roots.
If you live in an area with watering restrictions, tall fescue might be easier to manage. It can survive longer without water, even if it looks brown.
Heat Tolerance And Dormancy
This is where the climate really matters. Tall fescue is a cool-season grass. It grows best in the spring and fall. When summer temperatures soar above 85°F, it slows down. If it gets too hot and dry, it will go dormant to protect itself.
St. Augustine is a warm-season grass. It loves the heat. It grows vigorously during the summer months. It will stay green and lush as long as it has water. It goes dormant and turns brown only when temperatures drop below freezing in the winter.
In the transition zone (like the Carolinas, Tennessee, or Arkansas), tall fescue is often preferred because it stays green longer into the fall and greens up earlier in the spring. St. Augustine has a longer dormant period in these areas.
Maintenance And Mowing Requirements
You need to think about your weekend time. Tall fescue requires more frequent mowing during its active growing seasons. You should mow it to a height of 3 to 4 inches. This helps shade the soil and keep the roots cool.
St. Augustine should be mowed higher, at 3.5 to 4 inches. It grows fast in the summer, so you may need to mow it every 5 to 7 days. If you cut it too short, you will scalp it and encourage weeds.
Here are some mowing tips for each:
- For Tall Fescue: Keep the blade sharp. Never remove more than 1/3 of the leaf blade at a time. Leave the clippings on the lawn to return nitrogen to the soil.
- For St. Augustine: Use a rotary mower with a sharp blade. Mow when the grass is dry. Do not bag the clippings unless the grass is very tall and clumping.
St. Augustine also needs more fertilizer. It is a heavy feeder. You will need to apply nitrogen regularly during the growing season. Tall fescue needs less fertilizer, but it does benefit from a feeding in the fall.
Thatch Buildup
St. Augustine is prone to thatch buildup. Thatch is a layer of dead and living stems that accumulates between the soil and the grass blades. Because it spreads by stolons, it creates a lot of organic matter. You will need to dethatch or aerate your lawn every few years to prevent problems.
Tall fescue does not build thatch as quickly. Since it grows in clumps, it does not create the same dense mat of runners. Aeration is still beneficial, but you will not need to dethatch as often.
Pests And Disease Resistance
Both grasses have their share of problems. Tall fescue is susceptible to brown patch fungus, especially in humid conditions with high nitrogen levels. It can also get gray leaf spot. These diseases can cause large, irregular patches of dead grass.
St. Augustine is also prone to brown patch and gray leaf spot. However, its biggest enemy is chinch bugs. These tiny insects suck the sap from the grass, causing it to turn yellow and die. You need to monitor for chinch bugs regularly in the summer.
Here is a quick list of common issues:
- Tall Fescue: Brown patch, red thread, and billbugs.
- St. Augustine: Chinch bugs, large patch, and take-all root rot.
If you do not want to deal with pests, tall fescue might be slightly easier. However, both require vigilance and proper cultural practices to stay healthy.
Establishment And Installation
How you start your lawn is very different. Tall fescue is almost always established from seed. You can seed a new lawn in the fall or early spring. Fall is the best time because the soil is still warm, but the air is cool. This allows the seed to germinate and establish roots before winter.
St. Augustine is rarely grown from seed. The seed is not commercially viable for home lawns. You must purchase sod or plugs. This is more expensive upfront. You can install sod any time of year, but spring and summer are best for root establishment.
Here is a cost comparison:
- Tall Fescue: Lower upfront cost. A bag of seed is relatively cheap. You can cover a large area for a small investment.
- St. Augustine: Higher upfront cost. Sod is expensive per pallet. Plugs are cheaper but take longer to fill in.
If you are on a budget, tall fescue is the clear winner. If you want an instant lawn and have the money, St. Augustine sod gives you immediate ground cover.
Weed Control
Tall fescue lawns are easier to manage with pre-emergent herbicides. Because the grass is clumping, there is more space for weeds to germinate. You will need to apply a pre-emergent in the spring and fall to stop crabgrass and other weeds.
St. Augustine is more sensitive to herbicides. Many common weed killers will damage or kill it. You have to use specific products that are safe for St. Augustine. This can make weed control trickier and more expensive.
Which Grass Is Best For Your Lawn?
Now you have the facts. The choice really depends on your location and your yard. Let’s break it down into simple scenarios.
Choose Tall Fescue If:
- You live in a transition zone with cold winters.
- You have a yard with full sun to partial shade.
- You want a lower upfront cost.
- You have kids or pets that play on the lawn.
- You prefer a finer-textured grass.
Choose St. Augustine If:
- You live in a deep south, coastal climate.
- You have heavy shade from trees.
- You want a thick, carpet-like lawn.
- You are willing to water more frequently.
- You do not mind the higher maintenance and cost.
If you are still unsure, look at what your neighbors are growing. If most lawns in your area are tall fescue, it is probably the better choice for your soil and climate. The same goes for St. Augustine.
Transition Zone Considerations
The transition zone is the area where neither cool-season nor warm-season grasses are perfectly happy. This includes parts of Virginia, North Carolina, Tennessee, and Arkansas. In this zone, tall fescue is often the recommended choice. It handles the temperature swings better than St. Augustine.
St. Augustine can survive in the transition zone, but it will have a longer winter dormancy. It might also suffer from winter kill if temperatures drop too low. If you want a green lawn year-round in these areas, tall fescue is the safer option.
Frequently Asked Questions
Here are some common questions about these two grasses.
Can I Mix Tall Fescue And St Augustine?
It is not recommended. They have different growth habits and maintenance needs. Tall fescue grows in clumps, while St. Augustine spreads. They will look patchy and compete with each other. Pick one or the other.
Which Grass Stays Green In Winter?
Tall fescue stays green in the winter in most areas. It is a cool-season grass that grows actively in cooler weather. St. Augustine goes dormant and turns brown after the first frost.
Is St Augustine More Expensive Than Tall Fescue?
Yes, St. Augustine is more expensive. The sod is costly, and it requires more water and fertilizer. Tall fescue is cheaper to establish from seed and costs less to maintain over time.
What Is The Best Shade Grass For The South?
St. Augustine is generally the best shade grass for the deep south. It tolerates more shade than tall fescue. However, it still needs at least 4 hours of sun to thrive.
Can Tall Fescue Handle Full Sun?
Yes, tall fescue handles full sun very well, especially in cooler climates. In the deep south, it might struggle in extreme heat unless you water it regularly. It does best with some afternoon shade.
Final Verdict
There is no single “best” grass. It all depends on your priorities. If you want a low-maintenance, drought-tolerant lawn that is easy on the wallet, tall fescue is your grass. It is durable and handles traffic well.
If you want a lush, thick, tropical-looking lawn and you have the time and money to care for it, St. Augustine is the way to go. It looks amazing in the summer and handles shade better.
Take a look at your yard. Check the sun exposure, think about your watering habits, and consider your budget. That will give you your answer. Both grasses can create a beautiful lawn when they are planted in the right location and cared for properly.
Remember to get a soil test before you plant anything. This will tell you what nutrients you need to add. Healthy soil is the foundation for any successful lawn, regardless of which grass you choose. Good luck with your lawn project.