St. Augustine grass is a warm-season turf variety recognized for its thick, coarse texture and rapid spread, making it a popular choice in southern climates. This grass propagates aggressively through above-ground stems known as stolons, which root easily at the nodes to form dense mats of turf. The challenge in completely removing this turf lies in the deep and widespread network of these runners. To achieve total eradication, every piece of the living stolon network must be neutralized, as even small fragments can quickly regenerate and re-establish the lawn. The deep, interwoven root system demands thorough and multi-step approaches to ensure the grass does not return.
Non-Chemical Methods for Total Eradication
For smaller areas, physically removing the grass and the underlying soil layer is the most direct approach to ensure all growing structures are eliminated. St. Augustine stolons often root deeply into the top one to two inches of soil, requiring the removal of this entire layer to ensure all growth nodes are gone. For larger lawns, renting a commercial sod cutter can mechanically slice the turf layer free, making it easier to roll up and discard. This motorized machine cuts the sod at a shallow depth just below the roots.
An alternative is to block all sunlight from reaching the grass, starving the plants of energy. This technique, often called sheet mulching, involves covering the entire area with opaque materials like thick cardboard or heavy black plastic sheeting. The barrier must extend at least a couple of feet beyond the visible edge of the turf patch to catch any creeping stolons that may be running underneath. The smothering process is slow, typically requiring a minimum of two to three months during the active growing season to completely kill the turf.
A different passive method involves leveraging heat to kill the grass and any dormant seeds in the topsoil through solarization. This requires covering the moist, pre-cut lawn with clear plastic sheeting, securely sealing the edges to trap heat. The clear plastic creates a greenhouse effect, raising the soil temperature high enough to cook the plant tissues and roots. Effective solarization usually takes between four to eight weeks during the hottest months of the year.
To maximize the effectiveness of solarization, the ground must be moistened before the plastic is laid down, as moist soil conducts and retains heat better than dry soil. The edges of the plastic must be completely buried with soil or weighted down to prevent heat from escaping. Consistent monitoring after the initial removal is necessary to address any small patches of regrowth arising from missed stolon fragments.
Chemical Removal Strategies
Due to the aggressive nature of St. Augustine grass, total eradication requires the use of a non-selective herbicide, such as a product containing glyphosate. Selective herbicides are ineffective for complete removal because they target specific types of plants and will not reliably kill the entire stolon network. Non-selective options kill any plant tissue they contact.
The herbicide must be applied when the St. Augustine grass is actively growing, typically during the warm spring or summer months, to ensure the chemical is properly translocated throughout the plant. Applying the product to dormant or stressed grass may only kill the leaves, leaving the deep stolons unaffected and able to regrow.
It is often necessary to conduct multiple applications to achieve complete death of the lawn, as a single treatment rarely reaches all parts of the dense mat. A second treatment should be applied approximately two to four weeks after the initial application, targeting any areas that show signs of survival or new growth. This staged approach ensures that surviving stolon fragments have been completely neutralized before proceeding to soil preparation.
Always read the product label thoroughly, paying attention to re-entry intervals and dilution rates. To protect surrounding desirable plants, a physical barrier or careful spot-treatment should be employed to prevent drift. Application should be timed to avoid rainfall for at least 24 hours after spraying, allowing the herbicide sufficient time to be absorbed by the plant tissue.
Preparing the Area for New Growth
Once the St. Augustine grass is entirely dead, the extensive layer of thatch and dead stolons must be thoroughly removed from the area. This debris, which can be quite thick and fibrous, should be raked out or removed using a power rake. Removing this material is necessary because leaving it behind can impede the establishment of new roots and prevent the new sod or seeds from contacting the underlying soil.
Before planting new turf or landscape elements, testing the soil is highly beneficial to determine its current nutrient profile and pH level. Amending the soil with organic matter, such as compost or well-rotted manure, will improve soil structure and water retention. Proper soil structure is paramount for the success of any replacement plantings.
Vigilance is required to prevent the aggressive grass from creeping back into the newly prepared area. Installing a deep, permanent edging or root barrier along the perimeter can physically block new stolons from entering the space. Choosing a replacement turf or groundcover that is less aggressive will make it easier to manage any future stray St. Augustine growth.