Weed And Seed St Augustine Grass

Popular in the Southern United States, St Augustine Grass is a fast-growing, shade-tolerant grass that thrives in warm temperatures. St. Augustinegrass (Stenotaphrum secundatum), sometimes referred to as Charleston grass, is a coarse-textured, spreading grass that is popular throughout… With proper maintenance, you can help keep your St. Augustinegrass lawn dense, healthy and attractive. It grows well in nearly all soil types.

The Pros and Cons of St Augustine Grass – How to Establish & Care for St Augustine

St. Augustine Grass grows well in warm, humid regions of the country. Characteristically grown near the coast, this grass has regional names varying from Charleston grass (east coast), buffalo turf (Australia), buffalo grass (South Africa) and carpetgrass (California). Although St Augustine can be found throughout the southern United States, it is native to the Gulf of Mexico area.

St Augustine Table of Contents

Advantages of St. Augustine Grass

  • Shade tolerant
  • Heat tolerant
  • Tolerates wide range of pH levels
  • Tolerates moderate foot traffic
  • Endures wet conditions very well
  • Chokes out weeds
  • Quick post-winter green-up
  • Stays green during drought

In a nutshell, it’s tough as an old boot.

St. Augustine Grass is very shade tolerant and makes a great choice for lawns that do not get ample enough sun for other species. It also does well in the high heat and drenching wet conditions typical for subtropical climates.

This coarse-textured, wide-flat bladed grass grows best in well drained, fertile soils and has an ability to grow in a wide range of soil pH levels (5.0-8.5). It is also tolerant of salt, which make it an ideal choice for areas with occasional saltwater spray.

St. Augustine can handle moderate foot traffic and will recover fairly quickly from injury. Additionally, it grows fast when established on nutrient-rich soil. The grass forms a dense layer of turf, especially at the soil level. These factors make it very effective at choking out weed competition.

Known for its deep, rich green color, St. Augustine greens up quickly coming out of the winter and hold this color well into the Fall after the first frost. If protected by a layer of leaves, St. Augustine will hold its color further into the winter months. St. Augustine will also hold its color better than other grasses during times of drought.

Disadvantages of St. Augustine Grass

  • Sensitive to cold temperatures
  • Susceptible to pests & diseases
  • Can’t tolerate heavy foot traffic
  • Cann’t be cultivated with seed

One of the biggest downsides to St. Augustine Grass is its sensitivity to cold temperatures, which limits its range to southern and coastal regions of the United States. This grass also needs irrigation and fertilization to develop an attractive lawn.

St. Augustine is susceptible to a wide variety of pests and diseases. Chinch bugs and St. Augustine Grass decline virus (SADV) being two of the most common.

Chinch bugs are the bane of many of St Augustine lawns! Chinch bugs use their mouthparts (lol… mouthparts) to suck moisture from the blades of grass, while also injecting with their saliva which inhibits water movement through the grass. As a result, damage will often resemble drought damage.

Treat damage with a pesticide such as Talstar P Professional Insecticide or if considering planting St. Augustine, use a chinch bug resistance variety like Floratam or Floralaw.

From time to time, St. Augustine might be impacted by other “grass pests” like webworms, armyworms, and mole crickets, which all can be controlled by pesticides. The one we recommend the most for St. Augustine is Talstar.

Lastly, in high traffic areas, St. Augustine isn’t the best choice due to the potential for damage and slow recovery.

Recovering From Damage Caused By Pests If your lawn has been affected by pests and you are looking for a recovery plan, read our article on How to Repair St Augustine Grass. × Dismiss alert

Establishment & Maintenance

St Augustine isn’t a heavy seeder and seeds are not generally available at a commercial level. So your options for establishing a new St Augustine lawn are using sod or St Augustine grass plugs.

In general, use sod to establish the grass over a large area and use plugs for small project areas or to fill in holes in your lawn.

Establishing a St Augustine Lawn Using Sod

  1. Measure the square footage of your project area
  2. Prepare your project area for the sod by clearing the area of existing vegetation and leveling the area as necessary
  3. Head to your local garden supply store and purchase enough sod for your project
  4. Once the sod is delivered, spread it out over the project area
  5. Keep the new sod moist for the first couple of weeks – NEVER let it dry out
  6. After a few weeks, reduce waterings to once per day
  7. After another few weeks, reduce the waterings to once or twice per week as needed

Establishing St Augustine Using Plugs

  1. Prepare the area for the new St Augustine plugs
  2. Measure your project area
  3. Purchase enough plugs to spread across the entire area
  4. Plant the plugs
  5. Keep the newly planted St Augustine grass plugs moist for two weeks
Mowing & Irrigation

Mowing height of St. Augustine lawns can vary depending on season and maintenance intensity. In heavy maintained yards, mow grass weekly during the spring and summer at a height of 2”. In this plan, it is important that the grass gets adequate water (1” per week). For less maintenance, as well as fallwinter care, mow the grass between 2-4”. Not following proper maintenance, much like over fertilizing, will cause a detrimental thatch layer to form. Grass clippings do not have to be bagged, or removed, unless they clump together on the surface. In this case, a simple leaf blower can be used to break up the clots.

Fertilizing

A fertilizing program is needed to maintain a beautiful yard of lush St. Augustine grass. However, if over fertilized, thatch will accumulate and impede further growth. Nitrogen, Phosphorus and Potassium are the common nutrients in fertilizers, potassium needed to build up winter resiliency and nitrogen being used to control growth and color. The more nitrogen used (up to 1lb per 1000 square feet), will cause the grass to turn darker green, however increase growth and need more frequent mowing.

Similar to mowing and watering, the level of maintenance will determine the fertilizer rate. For best conditions, add nitrogen in summer months (May-August) and add potassium in September (1lb per 1000 sqft). For less maintenance, reduce the applications rates by half.

Fertilizer should be applied onto dry grass and watered in to reduce the chance of burning the blades of grass.

Learn More Want more options for fertilizing your St Augustine lawn? Read about our recommended granule, liquid, and environmentally safe fertilizer options. × Dismiss alert

Weed Control

St. Augustine is fairly sensitive to the common weed herbicide, 2-4,D. Therefore, common weeds, easily controlled in other types of grass, may be more difficult in St. Augustine. If post-emergent weed control is needed, consider using a product with the chemical, atrazine.

St Augustine Frequently Asked Questions

What causes St Augustine grass to turn yellow?

The two most common causes of St. Augustine grass turning yellow is due to an iron or nitrogen deficiency. Iron is an essential element in chlorophyll production. Not only does chlorophyll help the plant absorb sunlight, but it also causes its green color. Iron deficiencies typically occur in the spring and are identified by green streaking on a yellow blade. Iron deficiencies can easily be corrected with an application of Ferti-Lome Chelated Liquid Iron.

If the blades of grass are a solid yellow color, is likely suffering from a nitrogen deficiency. To correct this problem, apply a fertilizer with higher nitrogen, or first number (N-P-K). In many situations, iron and nitrogen can be applied together.

Which St Augustine grass is best for shade?

Overall, St. Augustine handles shady areas better than most other grass species. However, optimal growth needs between 6-8 hours of direct sun. The most shade-tolerant varieties are Seville and Palmetto.

When should I plant St Augustine grass?

Spring or Summer, when the temperatures are at least 80 degrees. Like all new sod, St. Augustine needs to be water multiple times a day for the first couple of weeks. Then reduce watering to once a day. St. Augustine sod or plugs need at least 90 days to establish before the first frost.

When should I fertilize St Augustine grass?

This type of grass responds best to a split fertilizer treatment. Apply nitrogen in the summer months and potassium in the early fall.

When does St Augustine grass go dormant?

Soil temperature determines if St. Augustine stays green or goes dormant in cooler weather. When soil temperature falls, and remains, below 55 degrees Fahrenheit, the grass will go dormant. If in an area where soil temperature is always above this, the grass remains active.

When does St Augustine grass come out of dormancy?

As soil temperature rises above 55 degrees Fahrenheit, the grass will begin to turn green and become active.

Where does St Augustine grass grow?

St. Augustine can be found from North Carolina to Texas, however is predominately found near coastal areas. This grass thrives in areas with hot summers and mild winters. It also tolerant of salt water splash.

Where is St Augustine grass from?

Historically a coastal grass, St. Augustine grass varieties have “their roots” from the gulf coast of the United States, Caribbean and western Africa.

How to get St Augustine grass to grow back?

Proper maintenance of St. Augustine will encourage it to grow back. Follow our fertilizer recommendations of nitrogen in the summer months and potassium in the early fall. We recommend Ferti-lome St. Augustine Weed and Feed. Also, ensure that the lawn is getting at least 1” to 1 ½“ of water per week.

How to fix bare spots in St Augustine grass?

Remove any dead thatch before replacing or filling in bare areas with new sod or plugs. Once established, St. Augustine will quickly fill in bare areas.

Is St Augustine grass okay for dogs?

Dog urine can burn, or cause St. Augustine grass to turn brown. Encourage dogs to go away from the grass, or water areas after a dog has gone.

Is St Augustine grass shade tolerant?

St. Augustine grass is the most shade tolerant species of warm season grasses. However, for maximum growth, St. Augustine grass lawns need at least 6 to 8 hours of direct sunlight.

Is St Augustine grass drought tolerant?

This grass species is one of the more drought tolerant warm season grasses, however for optimal growth needs between 1” and 1 ½“ spread over one week.

Why does St Augustine grass turn brown?

St. Augustine will turn brown as it goes dormant during colder months. Dog urine can also cause the grass to turn brown. Lastly, dead St. Augustine grass will turn brown and crispy as it dries out in hot temperatures.

Will St Augustine grass choke out weeds?

A properly maintained St. Augustine yard forms a dense layer of turf that is extremely effective in preventing and choking out weeds. Follow our guide to maximize your St. Augustine lawn’s potential.

Will St Augustine grass grow in sand?

St. Augustine will grow in sandy soils, however will not grow in pure sand.

Will St Augustine grass spread?

When properly maintained, St. Augustine can be very aggressive and spread quickly. This is mainly due to runners, or stolons, that spread the grass above the soil. Follow our guide to maximize your St. Augustine lawn’s potential.

What kind of St Augustine grass do I have?

Determining the specific variety of St. Augustine grass can be difficult, even for an experienced turf expert. The most frequently planted variety is called Floratam. It is the easiest to maintain and most disease resistant. Seveville is the variety of choice for extremely shady areas. This variety has a finer blade than Floratam and can thrive with, as little as, 6-7 hours of direct sun.

Can St Augustine grass be overwatered?

Established St. Augustine grass lawns need around 1 ½“ of water spread out over a week. Overwatering your St. Augustine grass lawn can be problematic. Signs of overwatering include curled leaves, color change to grayish blue, soggy depressions, and in extreme situations, grass dieback.

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Can St Augustine grass grow in full sun?

St. Augustine grows very well in at least 6-8 hours of full sun. Full sun, combined with adequate irrigation, will maximize your lawns potential.

St. Augustinegrass Yearly Maintenance Program

St. Augustinegrass (Stenotaphrum secundatum), sometimes referred to as Charleston grass, is a coarse-textured, spreading grass that is popular throughout warmer regions of the Southern United States. It will turn brown with fall freezes and will be slow to green in the spring. It is the least cold tolerant of the warm-season turfgrasses. See HGIC 1211, St. Augustinegrass for additional information on care and cultivar selection.

St. Augustinegrass is a wide-bladed, spreading, warm-season turfgrass that is adapted to the warmer regions of the southeastern United States.
Joey Williamson, ©2018 HGIC, Clemson Extension

Producing a yearly maintenance calendar for managing turfgrass consistently year after year can be difficult in a state with such a diverse climate as South Carolina. Therefore, it is important to monitor temperatures and apply the needed management practices based on that year’s climate. Important times to monitor the weather are during late winter or early spring when the turf is coming out of dormancy and early autumn when the first frost is forecasted. Last frost dates and first frost dates can vary by several weeks from the coastal areas of South Carolina to the foothills of the Upstate.

This turfgrass maintenance calendar may be used on turf grown throughout the state; however, management practices may need to be adjusted based on the year’s climate and the region where the turf is grown.

January through April

Mowing: Mow the lawn slightly lower than the regular summer mowing height. The mower setting should be between 2 to 2½ inches high. Be careful not to set the mower too low, as it may scalp the lawn. This height reduction should be done just before the lawn greens up, which usually occurs during late April or early May. If possible, use a mower with a bagger to collect the clippings and remove the dead material left from winter dormancy. Be sure to use a sharpened mower blade. Alternatively, the lawn can be hand raked to remove the excessive dead leaf material from the lawn surface.

A sharp mower blade will cleanly cut the grass blades as opposed to tearing the leaves. Dull mower blades rip rather than cut the grass and make the grass more susceptible to diseases. Sharpen the mower blade monthly or as needed during the growing season.

A dull mower blade will shred the turfgrass foliage.
Gary Forrester, ©2018, Horticulture Extension Agent, Clemson University

The date of initial turf green-up can be quite variable. In the coastal and more Southern regions of South Carolina, this generally will occur sometime during April, but further inland, this may be as late as mid-May. It is not unusual for St. Augustinegrass to green up and be burnt back several times during the late winter or early spring due to late season frosts. For more information on mowing, refer to HGIC 1205, Mowing Lawns.

Thatch Removal: If a thatch layer becomes a problem, use a dethatcher or vertical mower to remove it. For St. Augustinegrass, consider dethatching when the thatch layer is greater than ½ inch. For best results, use a dethatcher with a 2- or 3-inch blade spacing set at a ¼-inch depth after the turf has fully greened-up. Do not use a power rake with a 1-inch blade spacing, as severe turf injury may result. Use a lawn mower with a bag attached or hand rake to collect and properly dispose of the turf material pulled up. For more information on thatch removal, see HGIC 2360, Controlling Thatch In Lawns.

Aerification: Core aeration is the process of punching small holes into the turf and soil to alleviate compaction, allowing air to get to the root system. This will help to correct problems associated with poor infiltration and drainage. Once the threat for spring frost has passed and the lawn is fully greened-up, lawn aerification may be combined with dethatching to alleviate soil compaction and thatch problems.

However, if a pre-emergent herbicide was applied late February to mid-March, postpone any cultivation practices that will disturb the soil until just before the next pre-emergent herbicide application date. Pre-emergent herbicides create a barrier that keep weed seeds from germinating. Disturbing the soil after an application will allow weeds to emerge through this barrier. For more information on aerification, see HGIC 1226, Turfgrass Cultivation and HGIC, 1200 Aerating Lawns.

Weed Control: To control crabgrass, goosegrass, sandspurs, and other summer annual weeds, apply a pre-emergent herbicide early in the year. Approximate application times are mid-February in the coastal and central areas and mid-March in the piedmont/mountain areas. A second application is needed approximately 8 to 10 weeks after the initial application to give season long control of annual warm-season weeds.

Apply a post-emergent herbicide as needed to control existing winter weeds. In general, do not apply post-emergent herbicides to the lawn once the turf begins to green. If a weed problem begins and the grass has begun to green with warmer temperatures, wait until the grass has fully greened-up before applying a post-emergent herbicide. In the meantime, mow and bag the weeds. St. Augustinegrass is sensitive to certain herbicides, such as 2,4-D, not only during spring green-up, but also during hot summer temperatures. Follow label directions for use of any herbicide and use with caution during these times. For more information on weed control, see HGIC 2310, Managing Weeds in Warm-Season Lawns.

Insect Control: Cold winter temperatures will help usually keep insect problems at bay. As temperatures start to warm in late spring, monitor for mole cricket and chinch bug activity. If either insect is observed, apply a lawn insecticide when damage becomes excessive. If the damage is minimal, monitor the activity and wait before applying an insecticide. This is not the best time to apply an insecticide because of the cool soil temperatures and reduced insect activity. However, an early spring warm-up can lead to both mole cricket and chinch bug activity. Heavy populations can be reduced with appropriately timed insecticide treatments during this period. For more information on mole cricket or chinch bug control, see HGIC 2155, Mole Cricket Management in Turfgrass or HGIC 2487, Chinch Bugs.

If grubs (the white larvae of beetles, such as Japanese beetles) have been a problem in previous years, monitor them by cutting a square foot piece of sod on three sides and peeling it back. If more than six grubs are found under the sod piece, apply a lawn insecticide labeled for grub control according to label directions. For more information on white grub management, see HGIC 2156, White Grub Management in Turfgrass.

Fertilization: Fertilization of St. Augustinegrass should be based on soil test results, and this is a good time to test soil. However, fertilizers containing nitrogen should not be applied during this period. If new turfgrass growth is encouraged by fertilization during the early spring, and it is followed by a late frost, this can result in significant damage to the lawn. See HGIC 1652, Soil Testing for instructions on how to properly submit a soil sample.

Irrigation: During dormancy, water the lawn to prevent excessive dehydration. Winter desiccation can be a problem during dry winters. Watering to prevent drought stress can help eliminate turf loss during the winter.

Most areas of South Carolina receive enough rainfall during the winter to avoid winter desiccation of lawns. However, this is not always the case. Monitor the winter rainfall on a regular basis, and apply water to the turf if no measurable rain occurs over a 3 to 4 week period. This is especially important if warm, bright days preceed days forecasted to be in the low 20’s or colder. The added moisture in the soil will help keep the growing points of the turf warmer, preventing crown death.

To manage a lawn, it is important to know the soil texture in the top foot of soil. Sandy soils do not hold moisture well since they drain freely and dry out quicker. Clay soils, however, will hold moisture for a longer period of time. Be sure to not allow the lawn to stay excessively wet if the lawn has a clay soil. If the soil stays saturated all winter, this can cause many other problems. A soil probe can be used to monitor soil moisture. For more information, refer to HGIC 1207, Watering Lawns and HGIC 1225, Conservative Turfgrass Irrigation.

May Through August

Mowing: The ideal mowing height for St. Augustinegrass can range from 2½ to 4 inches depending on the specific site and management regime and is best determined by the growing conditions. Lawns in shady areas perform better when mowed at 3 to 4 inches high.

During periods of environmental stress due to high temperatures or a lack of rainfall, raise the mowing height ½ to 1 inch until the stress is eliminated. Always mow with a sharp blade using a mulching type mower, which leaves the clippings to decompose on the turf. The mower blade needs to be sharpened on a regular basis – usually about once a month or at least before the growing season starts. If the bag is picking up soil, mainly sand, when the lawn is mowed, then the blade may need to be sharpened more often than once a month.

Fertilization: Always fertilize and add lime or sulfur based on a soil test. St. Augustinegrass will grow best at a pH of 6 to 6.5. If a soil test indicates a higher soil pH, sulfur can be applied to lower it. Apply 5 lbs of pelletized sulfur per 1000 square feet of turf. Apply sulfur only when the air temperatures are below 75°F. In 3 months, recheck the soil pH and see what change was made. It may take several years to make a large pH change. Soils in the upstate are typically acidic and rarely need sulfur applications but usually do need lime.

St. Augustinegrass lawns should receive 2 to 4 pounds of actual nitrogen per growing season, per 1000 square feet of turf. The higher rate may be chosen for those growing St. Augustinegrass on sandy soils with the lower rate for those lawns growing on clay soils. An application of a soluble iron product, such as iron sulfate or a commercial chelated iron, in between fertilizer applications, will enhance the green color without encouraging growth. St. Augustinegrass should be fertilized three times during the summer, as recommended below. However, in the piedmont and midlands of SC where the turf is growing on clay soils, St. Augustinegrass is typically fertilized only twice during the growing season (early May and early July).

Early Summer (May): Apply ½ to 1 pound of actual nitrogen per 1,000 square feet in early May after the lawn fully greens up. The rate will depend on soil type. A soil test will help determine if a fertilizer containing phosphorous is required. See the section on fertilizer calculations below to determine how much granular fertilizer should be applied.

Mid-summer (June through July): Fertilize with ½ to 1 pound of actual nitrogen per 1,000 square feet, depending on soil type, using a high potassium fertilizer such as 15-0-15. This fertilizer may be especially important if the soils are sandy. The addition of phosphorous, the middle number in the fertilizer analysis, should only be applied if recommended by a soil test.

Late Summer (August): Fertilize with ½ to 1 pound of actual nitrogen per 1,000 square feet, depending on soil type, before August 15 using a high potassium fertilizer such as 15-0-15. The addition of phosphorous, the middle number in the fertilizer analysis, will need to be determined by a soil test. Potassium is needed late in the growing season as the grass goes into dormancy for added disease protection and winter hardiness.

Nutrient Deficiencies: A yellow appearance during the growing season may indicate an iron deficiency due to excessive phosphorus and/or a high soil pH. A long-term approach is needed to correct either cause, but an iron product can be added to quickly enhance turf color between the spring and summer fertilizer applications.

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NOTE: A yellow appearance may also develop during early spring. This could indicate an iron or manganese deficiency due to soil temperatures lagging behind air temperatures, high pH soils, or high phosphorous levels. Spraying with liquid iron (ferrous sulfate) at 2 ounces in 3 to 5 gallons of water per 1,000 square feet or applying a chelated iron product will help to enhance turf color. Fertilizing with a micronutrient fertilizer, such as manganese sulfate, can alleviate manganese deficiencies. However, as the soil temperatures start to climb, the yellowing should slowly go away. Lime or sulfur may also be added if a soil test indicates a need. Be aware, it could take several months for lime and sulfur applications to affect the soil pH.

Fertilizer Calculations: To determine the amount of granular fertilizer needed to apply ½ pound of actual nitrogen per 1,000 square feet, divide 50 by the first number on the fertilizer bag. To determine the amount of product required to apply 1 pound of actual nitrogen per 1,000 square feet, divide 100 by the first number on the fertilizer bag. This will give the number of pounds of product to apply to 1000 square feet of turf. See HGIC 1201, Fertilizing Lawns for more information.

Irrigation: Water the lawn to prevent drought stress. Monitor the lawn on a regular basis to assess the need for irrigation. When the entire lawn appears dry, apply ¾ to 1 inch of water the next morning. Wait to irrigate again until the lawn shows moisture stress. There are several ways to determine when the lawn needs watering. One way is to observe the lawn daily. When the turf begins to dry, it will appear to have a bluish hue. Another method is to walk across the lawn late in the evening. If the grass blades in the footprints bounce back up, then there is plenty of moisture in the turf. If the grass in the footprints does not bounce back, then irrigate the lawn the next morning.

The irrigation interval will vary from site to site depending on the environmental conditions at that site and soil type. The general rule to turfgrass irrigation is to water “deeply and infrequently”. Localized dry spots or hot spots can be watered as needed by hand. The irrigation system should only be run when the entire lawn is dry. For more information on turfgrass watering, see fact sheet HGIC 1225, Conservative Turfgrass Irrigation.

Insect Control: There are various insects and related pests that may infest St. Augustinegrass during the summer months. Mole crickets, chinch bugs, spittlebugs, grubs, ground pearls, and nematodes can cause considerable damage. Each pest problem has its own management strategy and is usually handled with cultural and chemical controls. However, there can be exceptions. Mole crickets and grub eggs will usually hatch mid-summer. Insecticide applications targeted at the mole crickets in their smaller nymph stage are the most effective controls, even if damage has not yet occurred. If either of these insects was a problem early in the season, apply an insecticide during mid-July to control the younger immature insects.

Chinch bugs can be very destructive to St. Augustinegrass. Monitor the turf on a regular basis during the growing season, especially during hot, dry periods. Damage is often more severe in sunny areas near driveways, sidewalks, or roadways, where the turfgrass is under more heat stress. A chinch bug is a small black insect with silver wings that sucks plant juices from the stem. An infestation may cause the turf to die, which will need to be replaced or allowed to grow back in.

Chinch bugs are fairly easy to control using general insecticides, but applications need to be made before the population has risen to a level where damage is occurring. Research has shown that an early season insecticide application after the turfgrass has greened-up will reduce the late season activity. When applying insecticides for chinch bug control during the summer, rotate chemical families or mode of actions to reduce the chance of pesticide resistance.

Disease Control: The most common diseases that affect St. Augustinegrass during the growing season are large patch (formerly known as brown patch) and gray leaf spot. Large patch is a fungal disease that is active during warm, humid spring and fall weather. Since it is fueled by moisture, it is important to maintain a rather dry condition in the lawn by employing proper watering practices, as well as providing adequate soil drainage.

If the turf stays wet, circular yellow to brown areas may begin to develop and slowly grow in size. Later, the center of the circle may start to re-green. In heavily infested turf, the rounded areas may grow together and no longer appear circular. If the turf at the edge of the dying area shows a smoky brown, rotted appearance, it will be necessary to apply a fungicide treatment. For more information, please see HGIC 2150, Brown Patch & Large Patch Diseases of Lawns.

Gray leaf spot may occur on St. Augustinegrass during the heat of summer when the turf remains damp for extended periods, usually during rainy periods or on newly laid sod being kept wet. There will be small purplish spots on the leaves and at an advanced stage, the grass will have a scorched appearance. At this point, a fungicide application will be needed. Please see HGIC 2151, Gray Leaf Spot on St. Augustinegrass.

Overall, proper water management, fertilization, mowing height, and thatch control are essential to curtail large patch and gray leaf spot problems. To help reduce disease problems, fertilize and lime St. Augustinegrass according to a recent soil test report.

Weed Control: A selective, annual grass and/or broadleaf weed control pre-emergent herbicide that is labeled for use on St. Augustinegrass and applied during late winter and spring will reduce many weeds the following summer. If a pre-emergent herbicide was not applied in the spring, the resulting weeds will need to be controlled using postemergent herbicides.

Summer weeds, such as spurge and annual lespedeza can be managed by using a post-emergent herbicide for broadleaf weeds sometimes referred to as a 3-way mix. Three-way herbicides typically contain 2,4-D. St. Augustinegrass is sensitive to 2,4-D, so follow label directions for mixing and use. Do not apply herbicides unless grass and weeds are actively growing and are not suffering from drought or heat stress; therefore, water the lawn thoroughly the day before application. Additionally, do not apply post-emergence herbicides when the turf is emerging from winter dormancy or when the summer temperatures are 90 °F or higher. Do not mow the lawn 3 days prior or 2 days after application. As with all pest control, proper weed identification is essential for best control options. Contact the local County Extension Office or the Clemson Home & Garden Information Center for identification and control of weeds in the lawn. For more information on weed control, see HGIC 2310, Managing Weeds in Warm Season Lawns.

Renovation: Replant large bare areas in May using sod, plugs, or sprigs (5 bushels per 1,000 square feet). For more information, refer to HGIC 1204, Lawn Renovation.

September through December

Mowing: Continue to mow St. Augustinegrass at the normal mowing height until the weather starts to cool in the fall. Once nighttime temperatures fall below 70 °F, raise the mower cutting height ½ to 1 inch to allow more leaf surface. This will allow the turf to become acclimated by the time the first frost occurs.

Fertilization: Do not apply nitrogen at this time. Lime or sulfur may be applied if recommended by a recent soil test. Potassium, typically known as potash, may be applied to enhance winter hardiness if a recent soil test indicates low to medium levels of potassium. Apply 1 pound of potash (K2O) per 1,000 square feet, 4 to 6 weeks before the first expected frost, using 1.6 pounds of muriate of potash (0-0-60) or 2 pounds of potassium sulfate (0-0-50) per 1000 square feet.

Irrigation: In the absence of rainfall, continue to water to prevent drought stress. After the lawn has become dormant, water as needed to prevent excessive dehydration. This is especially important if warm, bright days proceed days forecasted to be in the low 20’s or below.

Insect Control: Any insects that were missed during the nymphal stage in the summer will have grown to a size where turfgrass damage is occurring. Apply an insecticide to reduce the population and reduce further turf damage. This is best done before the first frost.

Disease Control: For disease control, especially large patch, it is extremely important to treat with fungicides during the fall months. With warm temperatures through September and the possibility of excessive rainfall that may occur during that period, diseases can increase rapidly. However, with cooler nights and shorter day lengths, control can be quite difficult because of slow turf recovery during this time. Turf weakened by disease in fall will be slow to recover in the spring; therefore, fungicide applications are needed to control disease before the grass goes dormant. In certain situations where large patch has been prevalent yearly, a preventative fungicide application may be needed starting in early October to stay ahead of the disease. For more information on disease control, please see HGIC 2150, Brown Patch & Large Patch Diseases of Lawns.

Weed Control: Many winter annual weeds can be managed by applying a pre-emergent herbicide in September with a second application 8 to 10 weeks later. Follow all label directions on the product for application rate. Granular herbicides must be watered into the soil soon after application. Follow label directions as to post application watering.

Selective, post-emergent herbicides can be applied as necessary for control of chickweed, henbit, and other cool-season broadleaf weeds. St. Augustinegrass is sensitive to certain herbicides, such as 2,4-D, so follow label directions for reduced mixing rates. Spray sufficiently to wet the foliage, but do not spray excessively. Repeat application in 10 to 14 days, if needed. Selective herbicides may be applied in the winter for control of annual bluegrass and other winter annual weeds. For more information on weed control, see HGIC 2310, Managing Weeds in Warm Season Lawns. Contact the local County Extension office or the Clemson Home & Garden Information Center for weed identification and control measures.

Originally published 09/05

If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.

Original Author(s)

Trent C. Hale, PhD, Former Extension Turfgrass Specialist, Clemson University
Chuck Burgess, Former HGIC Horticulture Extension Agent, Clemson University

Revisions by:

Gary Forrester, Horticulture Extension Agent, Horry County Extension Service, Clemson University

This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.

Maintaining St. Augustinegrass Lawns

With proper maintenance, you can help keep your St. Augustinegrass lawn dense, healthy and attractive.

St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze) is a popular warm-season turfgrass for home lawns. It is found in the United States, southern Mexico, South America, South Africa, western Africa, the Caribbean, the Hawaiian Islands, Australia and the South Pacific.

St. Augustinegrass is medium to dark green and coarse textured. It grows well in nearly all soil types and tolerates shade, heat, salt and, to some degree, drought. It does not tolerate waterlogged soils or extended periods of cold weather. St. Augustinegrass is an relatively aggressive lawngrass that spreads by aboveground stems called stolons. St. Augustinegrass can form a dense lawn that can tolerate light traffic and compete well with most weeds. St. Augustinegrass is the most shade tolerant warm-season turfgrass.

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Texas Common, Raleigh, Seville, Palmetto and Floratam are examples of St. Augustine varieties commonly used for home lawns in the southern United States. Variety availability will likely vary with location in the state since sod producers will grow varieties that are best adapted to their region. Contact your county Extension agent for information on the variety best suited for your location.

It is common misconception among homeowners that only a dark green lawn is a healthy lawn. This often leads to higher amounts of fertilizer and water than are required for the lawn to persist and may actually result in greater thatch, disease and insect problems. The following seasonal management guidelines can help you focus on management practices that will keep your St. Augustinegrass lawn in good condition. Because many factors affect turf growth, these are general recommendations.

MARCH through May

Mowing

Begin a routine mowing program as soon as the grass begins to green up in the spring. Mow often enough to remove no more than one-third of the leaf area with any one mowing. Set the mowing height at 21 /2 to 3 inches (3 to 31 /2 inches in shady lawns). The lower the mowing height, the more often you will need to mow. Frequent mowing at a lower height produces higher quality turfgrass.

It is best to recycle or mulch grass clippings. Grass clippings decompose quickly and return significant amounts of nutrients to the soil. If you must bag the clippings, consider composting them for use in the landscape.

Nutrient Management

Nitrogen fertilizer application on St. Augustine can range from 3 to 5 pounds of nitrogen per 1,000 square feet per year. The total annual rate depends upon desired quality, length of the growing season, recovery from traffic and a number of other factors.

Begin fertilizing 3 weeks after the grass turns green and when there is little chance of a late frost. Apply 3 /4 to 1 pound of soluble nitrogen per 1,000 square feet of lawn every 8 weeks, or 1 to 11 /2 pounds of slow-release nitrogen every 10 weeks. Have your soil tested to determine what additional nutrients your lawn may need. For information on soil testing procedures, contact your county Extension agent.

We strongly recommend that you have your soil tested once every 3 years. Besides testing for nutrients that may or may not be supplied by the soil, it will also determine soil pH and if there is a need for fertilizer or lime application. If the soil is not tested, a common recommendation has been to use a complete fertilizer with a 3-1-2 ratio of nitrogen, phosphorus and potassium (Examples: 15-5-10, 21-7-14, etc. Every bag of fertilizer has the nutritional analysis printed on the bag). However, not soil testing and using a 3-1-2 analysis may apply phosphorus when it is not needed. This could result in phosphorus runoff loss to surface water (streams and lakes) and contribute to a decline in aquatic habitat. Hence, the strong recommendation for soil testing.

To determine the amount of fertilizer needed to equal 1 pound of nitrogen per 1,000 square feet, divide 100 by the first number in the fertilizer analysis. For example, if you are using a 15-5-10 fertilizer, then you need 6.6 pounds per 1,000 square feet. (To determine the amount needed to apply 11 /2 pounds per 1,000 square feet, substitute 150 for 100.)

100 ÷ 15 = 6.6

Then determine the size of the area to be fertilized. If your lawn is 5,000 square feet, you will need 33 pounds of 15-5-10 fertilizer.

(5,000 ÷ 1,000) x 6.6 = 33 pounds of fertilizer

Watering

Irrigation may be needed to supplement natural rainfall. The trick is to water only when the grass needs it. When you do water, wet the soil to a depth of 6 inches. Then don’t water again until the grass shows symptoms of drought stress—a dull, bluish color, rolled or folded leaves, and footprints that do not “spring back.” Follow these steps to determine how long to water to apply the right amount your lawn needs.

  1. Set out five or six open-top cans randomly around the lawn (tuna or cat food cans work best).
  2. Turn on the sprinklers or irrigation system for 30 minutes.
  3. Using a ruler, measure the depth of water caught in each individual can, and record the depths.
  4. Calculate the average depth of water of all the cans.

Example: You have placed five cans in your yard. The depths of water in the cans were 0.5 inch, 0.4 inch, 0.6 inch, 0.4 inch and 0.6 inch. Add the depths together and divide by the number of cans you used.

0.5 + 0.4 + 0.6 + 0.4 + 0.6 = 2.5 inches

2.5 inches ÷ 5 cans = 0.5 inch of water in 30 minutes

New-style irrigation controllers allow you to water several times a day, so you can program them to prevent run-off.

  1. Use a garden spade or a soil probe to find out how deeply the soil was wet during the 30- minute period. The probe will push through wet soil easily, but it is more difficult to push through dry soil.
  2. When you know how much water was applied in 30 minutes and how deeply that volume of water wet the soil, then determine how long you must water to wet the soil to a depth of 6 inches.

Example: If the sprinklers sprayed 1 /2 inch of water in 30 minutes and wet the soil to a depth of 3 inches, you would need to apply 1 inch of water to wet the soil to a depth of 6 inches. To do so you must water for 1 hour.

Run-off from watering a lawn can waste a significant amount of water, which is costly and a poor use of a limited natural resource. The factors determining how quickly run-off occurs are the type of soil and the application rate of the sprinkler system. Do not apply water faster than the soil can absorb it. To prevent run-off:

  1. Check the lawn while watering. If water begins running into the streets or gutters, note how long it took before run-off occurred. This is the maximum amount of time you should water at one time.
  2. Stop watering and allow the soil surface to dry (30 minutes to 1 hour).
  3. Begin watering again and continue for the time you’ve determined. With an automatic irrigation system, change your timer to the new, shorter time.
  4. Continue this cycle until the appropriate amount of water has been applied to wet the soil to a depth of 6 inches.

Weeds

The best form of weed control is a healthy, dense lawn. To control summer annual grassy weeds (e.g. crabgrass and goosegrass), apply preemergent herbicides (which control weeds as the seeds germinate). The timing of preemergence herbicide application will vary greatly in Texas due to the onset of soil-warming temperatures required for weed germination. This may mean applying these products by late February in Houston or by late March in Dallas. These climatic conditions usually occur in spring about the time redbud and dogwood trees begin to bloom. Apply postmergent herbicides (which control weeds that have already sprouted) as needed. Apply herbicides only when weeds are present and when the grass is healthy and actively growing.

Postemergent weed control is most effective if you apply the herbicide when the weeds are still very small. St. Augustinegrass is very sensitive and may be injured by some herbicides, such as 2,4-D. Read the label carefully before applying any herbicide to ensure that it is the right product for the weeds you have and that you do not injure the turf. Follow all instructions on the label. It explains how and when to use the product and how much to apply.

Insects

Chinch bugs and white grubs are the two most serious insect pests in St. Augustinegrass lawns. Routinely check for these pests and treat as necessary. (See L-1766, “Chinch Bugs in St. Augustine Lawns,” and L-1131, “White Grubs in Texas Turfgrass,” available from Texas Cooperative Extension at http://tcebookstore.org.

Thatch

Thatch (a surface layer of undecomposed plant stem and roots) is likely to form on St. Augustinegrass lawns that are heavily fertilized and watered. A thatchy lawn is prone to drought and insect damage. If the thatch layer is more than 3 /4 inch thick, it can be removed gradually by mowing the lawn with a vertical mower or scalping the lawn (cutting with a rotary mower at its lowest setting) in April or May when the grass is healthy and actively growing. This practice will likely damage the lawn by it will recover if fertilized and watered properly.

Correcting compacted soil conditions

In areas of heavy traffic, aeration can help eliminate compacted soils. Use a core-aerating machine when the grass is actively growing. If you have an underground irrigation system, flag the sprinkler heads first to avoid damaging them.

JUNE through September

Mowing

Follow the same recommendations as for March through May.

Nutrient Management

Continue the fertilizer program begun in the spring, applying 3 /4 to 11 /2 pounds of nitrogen per 1,000 square feet every 8 to 10 weeks. Without soil test information, it is recommended that you use a fertilizer that either contains nitrogen only (21-0-0, ammonium sulfate) or is very low in phosphorus (Examples: 21-3- 6 or 15-0-15) to reduce the chance of excessive phosphorus buildup in the soil. High soil phosphorus levels may lead to its surface runoff in periods of excess rainfall or irrigation. This may eventually contribute to eutrophication of streams and lakes. High levels of soil phosphorus can also lead to deficiencies in iron and zinc.

To prevent yellowing caused by iron chlorosis, apply liquid or granular iron fertilizer throughout the growing season. Follow the label directions for the rate of application. Be aware that fertilizers containing iron may stain concrete, brick or stone surfaces.

Watering

Follow the same recommendations as for March through May.

Weeds

Apply postemergent herbicide as needed. Herbicides containing 2,4-D should be used with care, as St. Augustinegrass is sensitive to this herbicide. Herbicides may damage the lawn if you apply them when the temperature is higher than 90 ºF.

Insects

Follow the same recommendations as for March through May. The most effective time to treat for white grubs is in August when they are immature and close to the soil surface.

Eliminating compacted soils

Follow the same recommendations as for March through May.

SEPTEMBER through February

Mowing

Continue the recommended mowing practices until the grass goes dormant and does not require mowing.

Nutrient Management

Continue fertilizing as recommended until 4 to 6 weeks before the first expected frost. At that time, apply a low nitrogen, highpotassium fertilizer. Apply no more than 1 /2 pound of nitrogen per 1,000 square feet.

Do not fertilize St. Augustinegrass from December through February unless the lawn has been overseeded (planted with cool season grass for green color in the winter). Fertilize overseeded lawns once in December and again in February with 1 /2 pound of nitrogen per 1,000 square feet, using a nitrogen-only fertilizer such as ammonium sulfate (21-0-0).

Watering

Even though St. Augustinegrass is normally dormant in winter, you may still need to water it periodically when the weather is warm, dry and windy. If the lawn has been overseeded, water based on the earlier discussed principle.

Weeds

Winter annual grass and broadleaf weeds are not common in St. Augustinegrass. Therefore, it may be desirable to apply preemergent herbicides for annual winter weeds when the average soil temperature drops to 70 ºF. Your county Extension agent can give you an estimate of that date in your area. Apply postemergent herbicides as needed.

Insects

St. Augustinegrass lawns should experience no detrimental insect activity during the winter.

For more information see the Web site at https://aggieturf.tamu.edu.

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