www.clemson.edu/extension/hgic/

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.

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.

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.

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.

If an insect problem occurs, it is important to positively identify the problem and select the appropriate insecticide to apply. Contact the local County Extension Office, or the Home & Garden Information Center for positive identification and proper management strategies. For more information, see fact sheets: HGIC 2156, White Grub Management in Turfgrass; HGIC 2155, Mole Cricket Management in Turfgrass; HGIC 2488, Two-lined Spittlebug; HGIC 2157, Bermudagrass Mite, Rhodesgrass Mealybug, & Groundpearl; and HGIC 2487, Chinch Bugs.

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.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

Factsheet Number

Categories

Pin It on Pinterest

Share This