St. Augustine grass (Stenotaphrum secundatum) is a popular warm-season turf known for its lush, blue-green color and coarse texture. It forms a dense turf canopy, making it highly desirable for lawns in warmer regions. When establishing a new lawn or repairing large, damaged sections, plugs offer a practical and economic alternative to laying full sod. Using plugs is significantly more cost-effective, allowing homeowners to cover extensive areas by relying on the grass’s natural growth habit. The success of this method depends heavily on selecting the correct spacing, which determines the time required for the area to transform into a uniform lawn.
Determining the Ideal Plug Spacing
The distance between St. Augustine plugs is a direct trade-off between the initial investment cost and the time required for the lawn to fully fill in. St. Augustine grass spreads primarily through above-ground runners called stolons. The chosen spacing dictates how quickly these stolons will meet and knit together to form a seamless turf. Since the grass plugs have fully developed root systems, they begin sending out these runners shortly after planting.
18-Inch Spacing (Standard)
The most common recommendation for balanced coverage is to space the plugs approximately 18 inches apart, measured center-to-center. This standard approach usually results in the lawn filling in completely within 9 to 12 months under optimal growing conditions. This distance balances the cost of materials with a reasonable time frame for establishment.
12-Inch Spacing (Fastest Coverage)
To achieve the fastest possible coverage, plugs can be planted 12 inches apart, requiring about one plug per square foot. This denser spacing encourages the stolons to interconnect much sooner, often resulting in a fully covered lawn within 6 to 9 months. This option requires substantially more plugs, involving higher initial material cost and labor.
24-Inch Spacing (Budget Priority)
For homeowners prioritizing budget over speed, plugs can be spaced 24 inches apart. This wider spacing significantly reduces the number of plugs needed and lowers the initial expense. The drawback is a much slower establishment phase, often taking 12 to 18 months or longer to create a dense turf.
Preparing the Soil and Planting the Plugs
Proper preparation of the planting area is necessary to ensure the plugs establish themselves quickly. First, clear the area of all existing weeds, debris, and any remaining dead turf to prevent competition for water and nutrients. This removal process can be assisted by applying a non-selective herbicide two weeks before planting to ensure all competing vegetation is eliminated.
St. Augustine grass prefers well-draining soil with a slightly acidic to neutral pH, ideally ranging between 6.0 and 7.5. Performing a soil test provides specific information on the existing pH and nutrient levels, guiding any necessary amendments. The soil should then be loosened, typically to a depth of 3 to 4 inches, using a tiller or garden fork to help the new roots establish quickly and deeply.
When planting, use a plug tool or trowel to create holes wide enough for the root ball. Set the individual plug so its crown—the point where the blade meets the root—is perfectly level with the surrounding soil surface. Gently and firmly press the soil around the plug to eliminate air pockets that could dry out the delicate roots. Planting should ideally be done in a staggered or diamond pattern to promote faster, more uniform coverage as the stolons spread outwards.
Essential Care During the Establishment Phase
The initial weeks following planting represent an intense phase of care focused entirely on root establishment. For the first 10 to 14 days, the newly planted plugs require frequent, shallow watering to keep the root zone consistently moist but not saturated. This may mean watering two to three times daily, depending on the heat and sun exposure, to prevent the plugs from drying out before the roots can take hold in the surrounding soil.
Once the plugs show signs of firm rooting, the watering schedule should transition to less frequent but deeper applications. This encourages the root system to grow downward, increasing the grass’s resilience to heat and drought. After 4 to 6 weeks, when noticeable growth and runners begin to develop, apply a starter fertilizer containing phosphorus to support robust root development and encourage the outward spread of the stolons.
Mowing should begin once the plugs have grown sufficiently tall, which usually means the surrounding grass reaches a height of 3 to 4 inches. St. Augustine grass performs best when mowed at a relatively high setting, generally between 2.5 and 4 inches, to maintain a dense canopy. Avoid cutting more than one-third of the grass blade height at any single time, as this can cause stress to the young turf.