Maintenance of St. Augustine Grass Lawns

L. B. McCarty and John L. Cisar

Establishment

St Augustine grass is established by vegetative propagation because its seeds have poor germination and do not remain true to type.  St. Augustine grass is a stoloniferous grass (with above ground stems) and can be planted by sod, sprigs, or plugs (Table 1).  Each of these methods can be equally successful if the site is properly prepared and maintained before and after planting.

   New home or building sites should be rough graded.  Rocks, roots, and other debris need to be removed.  On existing sites, unwanted vegetation should be removed by a nonselective herbicide such as glyphosate (Roundup).  A soil test should be taken in the area to determine the pH and the need for plant nutrients.  These nutrients need to be applied before planting, and tilled in if the soil is bare.  The next step is the installation of a new irrigation system, or repairs to an existing system.  Before any grass is planted, the area should be final graded and thoroughly moistened to help the establishment process.

   The best time to plant St. Augustine is during active growth, normally April through July.  Other times may be suitable, with sufficient care to prevent desiccation and cold damage.  The chapters entitled “Preparing To Plant A Florida Lawn” and “Establishing Your Florida Lawn” in this publication give additional details on turf establishment.

Sodding

   Establishment of St. Augustine grass by sodding produces an instant lawn.  Sod should only be laid over bare, moist soil, with pieces laid in a staggered brick-like pattern and the edges fitted tightly together to avoid cracks.  Fill any cracks between strips with soil to avoid open spaces for weed encroachment.  Rolling and thorough watering will ensure good contact with the soil for fast rooting.  Sodded areas should be watered at least every other day with ½ inch of water until the sod is held fast to the soil by roots, then watering (3/4 inch) should be reduced to an as-needed basis.

Sprigging

   Planting St. Augustine grass by sprigging is an effective way to patch small areas unless it is performed mechanically.  Fresh springs are stolons (runners) that have at least two nodes or joints.  These are planted end to end in rows 6 – 12 inches apart.  The runner should be covered with soil, leaving the leaves exposed.  Tamping the soil and a thorough watering help establish the plants.  The soil should be kept moist until new stolons are produces.

Plugging

   A number of the new varieties of St. Augustine grasses are available commercially as plugs.  Sod also can be made into plugs by cutting it into small squares.  Spacing of plugs varies from 6- 12 inches.  The closer spacing provides full coverage in 3 – 6 months and farther spacing covers in 6 – 12 months.  Plugs are placed in holes of the same size or in open furrows and tamped into place.  A thorough watering completes the installation.  The turf should then be cared for like a sprigged lawn.

Mowing

   Proper mowing practices are important in maintaining an attractive lawn.  Both height and frequency of cut need to be adjusted for the level of turf management (Table 1).  Under high levels of management, St. Augustine grass can be maintained at 2 inches, if the lawn is mowed at least weekly during the growing season.  Mowing at this height and frequency requires more fertilizer and water to maintain an attractive lawn.  Also, low cutting heights and high maintenance levels can predispose the turf to many pest problems.  Under moderate or low levels of management, St. Augustine grass should be cut at a height of 3 – 4 inches.  To obtain this height with most home rotary lawn mowers, the highest wheel height setting should be used.  This height will help the grass develop a deep root system and give a better appearance to the turf.  Mowing frequency under moderate or low management should be adjusted to the amount of growth.  No more than one-third the height of the leaf blades should be removed with any mowing.  During periods of moisture stress, or if the grass is growing in shade, increase the mowing height to 4 inches.  Newer semi-dwarf varieties have a lower growth habit, and should be mowed at 1-1/2 – 2 inches for optimum quality.

   Mowing too infrequently can cause a thatch buildup.  The secret to mowing St. Augustine grass at 3 inches is to water the lawn only when there are signs of moisture stress.  This will keep growth to a minimum and reduce the rate of thatch accumulation.  The chapter entitled “Thatch and its Control in Florida Lawn” in this publication has more information on thatch.

   Mowing too low can also cause problems in turf quality.  Constant low mowing reduces the density and vigor of St. Augustine grass.  Weed problems in St. Augustine grass lawns can usually be attributed to a low height of cut and improper watering.

   Either a rotary or reel mower can be used on St. Augustine grass.  It is important to keep the blades sharp and well-adjusted to get a clean cut.  Dull blades will give the lawn a brownish cast,  because a ragged cut shreds the leaf blades rather than cutting them.  During the growing season blades should be sharpened on a monthly basis.

   Grass clippings can be left on a lawn that is mowed at the proper height and frequency.  Under these conditions, clippings do not contribute to the thatch layer.  Clippings should be left on lawns maintained with low to moderate fertility levels to help recycle nutrients.  Remove clippings if the amount is excessive (e.g., clumping occurs).

Watering

   The best way to irrigate an established lawn is on an as-needed basis.  Grass blades will begin to wilt (e.g., fold, turn bluish-green in color and not recover from traffic or foot printing) as the moisture begins to be depleted in the soil.  If 30% - 50% of the lawn shows signs of slight wilting, it is time to irrigate with ¾ inch of water.  The turf will fully recover within 24 hours.  The turf should not be watered again until it shows signs of wilting.  This irrigation schedule works for any soil type and environmental condition.  For further information on recommended watering practices see the chapter in this publication entitled “Watering Your Florida Lawn.”  Proper watering practices will help maintain a lawn that requires less mowing and has little thatch buildup.  Proper watering will also help develop a deep root system and encourage plants which are less susceptible to damage by pest and environmental stress.  If the diseased brown patch or gray leaf spot are a continuous problem, over watering and excessive nitrogen fertilization may be responsible.  Certain weeds (like pennywort and nutsedge) also thrive in soils which are continuously wet.  Regulate these management practices closely to reduce disease and weed severity.

Fertilizing

   Maintaining a good quality lawn requires a properly planned fertility program.  An acceptable quality St. Augustine grass lawn can be grown with a low to a high level of fertility, depending on what the homeowner wants (Plate 29).  First, decide how much time and effort can be spent on lawn maintenance.  A low fertility lawn is best for those with little time to spend on lawn care.  A high fertility lawn may be better suited to those who find a low fertility St. Augustine grass lawn unattractive, and have more time for lawn care.

   A low maintenance St. Augustine lawn should be fertilized twice a year, once in the spring and again in the late summer while the grass is actively growing (Table 2).  Apply a complete fertilizer such as 16-4-8, 10-10-10, or 6-6-6 with micronutrients at the rate of a 1 pound of actual nitrogen per 1000 square feet per application.  It is best to leave the clippings on these lawns to recycle nutrients.

   At the optimum maintenance level, a St. Augustine grass lawn should receive 4 pounds of nitrogen per 1000 square feet per year.  Apply fertilizer four times per year, In March, May July, and September, at the rate of 1 pound of actual nitrogen per 1000 square feet.  Never apply more than 1 pound of actual nitrogen per 1000 square feet at any one time.  A complete fertilizer can be used at every fertilization, although two applications per year is sufficient.  A slow-release, nitrogen only fertilizer may be applied in between complete fertilizer applications.  This fertility level, combined with the proper watering practices, will result in a good quality lawn with minimal thatch buildup.

   Heavy fertilization rates will produce a faster buildup of thatch than lower rates.  High rates of fertilizing can also encourage insect damage to the turf.  Additionally, the necessary amount of mowing and watering increases with the amount of fertilizer.  Careful planning is necessary to grow the desired type of lawn.  The chapter entitled “Understanding Soil Analysis and Fertilization” provides details on fertilizing turf grasses in north and south Florida.

Pest Problems

   Several pest problems can affect St. Augustine grass.  Diagnosis and recommendations for treatment of pest problems are available from your county Cooperative Extension Service.

Insect

   The major pest of St. Augustine grass is chinch bugs.  Large populations of this insect have become resistance to organophosphate insecticides.  Alternative chemicals are available, but the best solution is to plant Floratam or Floralawn, since these cultivars are resistant to chinch bugs.  Other insect pests, including webworms, armyworms, grass loopers, and mole crickets, can cause damage on St. Augustine grass.  High levels of nitrogen fertilizer encourage insect problems.  Refer to the chapters on specific insect pests for description  and information about their control.

Diseases

   Brown patch and gray leaf spot are the two major disease problems of St. Augustine grass.  Brown patch occurs in warm, humid weather and is encouraged by excessive nitrogen.  Brown patch is generally most noticeable during spring and fall months.  Gray leaf spot occurs during the summer rainy season and is primarily a problem on new grown.  Both diseases can be control with fungicides.  Refer to the section on disease problems for additional information.

Nematodes

   Several types of nematodes infest St. Augustine grass lawns.  Nematodes cause yellowing and general thinning of older lawns.  Refer to the section on nematodes or contract your county Cooperative Extension Service for Additional information.

Weeds

Weed problems in a lawn indicate that the turf has been weakened by improper management practices or damage from pests.  Proper management practices can eliminate most weed problems.  If weeds are a persistent problem, herbicides labeled specifically for St. Augustine grass should be used.  Many commercial weed and feed formulations will provide control, but they should not be used every time the lawn is fertilized.  Read and follow any pesticide label before use.  The chapter entitled “Weed Control Guide for Florida Lawns” gives specific weed control recommendations.

Other Problems

   Many other factors can decrease the quality of a lawn.  To insure a good St. Augustine grass lawn, refer to other sections of this publication for recommended management practices, and follow label directions when applying fertilizers and pesticides.

WATER ON YOUR DAY OR PAY!

Lake County Commissions approved the ordinance in April giving the enforcement division authority to enforce the rules established by the St. Johns River Water Management Division. Today it was released by Lake County that they would begin enforcing landscape irrigation rules on Monday, May 11. The first violation is a written warning. The second violation is a minimum $50.00 fine. Subsequent fines will double with each violation, up to a maximum of $1,000.00 for each violation.

The Plantation at Leesburg

is NOT SCHEDULED ON THE ODD EVEN SYSTEM

LANDSCAPE IRRIGATION IS PERMITTED

BETWEEN THE HOURS OF

4:00pm and 4:00am

AND BETWEEN 6:00am and 10:00am

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