Crabgrass is a warm-season annual weed that presents a persistent challenge to Texas homeowners due to the state’s long, hot growing season. This weed aggressively competes with desirable turf and rapidly produces seeds that ensure its return the following year. Effectively managing crabgrass requires a two-pronged strategy: proactive chemical prevention and responsive, turf-specific post-emergence treatment. Success relies heavily on precise timing and a commitment to long-term cultural practices that promote a dense, healthy lawn capable of naturally resisting invasion.
Pre-Emergent Timing and Application in Texas
Preventing crabgrass begins with applying a pre-emergent herbicide before the seeds germinate in the spring. This application creates a chemical barrier in the top layer of the soil that inhibits the development of the young crabgrass seedling. The success of this preventative step is dependent on soil temperature, not the calendar date.
Crabgrass seeds begin to germinate when the soil temperature consistently reaches 55°F for several consecutive days, typically measured at a depth of two inches. In North Texas, this window often opens in late February or early March, while in warmer South Texas and Central Texas regions, it can occur earlier. Monitoring local university extension reports or using a soil thermometer is more accurate than relying on air temperature or arbitrary dates.
Due to the extended Texas growing season, a single application of pre-emergent is rarely sufficient for season-long control. The initial spring application uses active ingredients like prodiamine or pendimethalin. Because most pre-emergent products provide protection for about 90 days, a second application is often necessary in mid-summer, around late May or early June, to control late-germinating crabgrass.
Proper application is as important as timing; the herbicide must be uniformly spread across the entire lawn to prevent gaps in the barrier. Following application, the product requires activation by water, usually needing a half-inch of irrigation or rainfall within 24 to 48 hours to move the chemical into the upper soil layer. Aerating the lawn or disturbing the soil after application will break the chemical barrier, allowing crabgrass to sprout through the damaged areas.
Post-Emergent Removal Based on Turf Type
Once crabgrass has sprouted and is actively growing, a post-emergent herbicide is necessary to kill the visible plants. This treatment must be selected carefully based on the type of warm-season turfgrass common in Texas, as many broad-spectrum products can damage desirable grass. Post-emergent applications are less effective than pre-emergent controls and often require multiple treatments spaced several weeks apart.
For lawns primarily consisting of Bermuda grass, the turf is robust and tolerates more aggressive chemical treatments. The active ingredient quinclorac is highly effective for post-emergent crabgrass control in Bermuda grass, even targeting mature plants. Quinclorac works systemically, meaning the crabgrass absorbs the product through its leaves, and it is then transported throughout the plant to ensure a complete kill.
In contrast, St. Augustine and Zoysia grass are significantly more sensitive to herbicides, and products containing quinclorac or broadleaf killers like 2,4-D should be avoided as they can cause severe injury. For these sensitive turf types, a safer option is an herbicide containing the active ingredients thiencarbazone-methyl, iodosulfuron-methyl-sodium, and dicamba, often sold under the trade name Celsius. Atrazine is another compatible option, providing both pre- and post-emergent control for St. Augustine lawns.
When treating crabgrass in St. Augustine or Zoysia, spot treatment is the preferred method to minimize stress on the surrounding turf. Precisely targeting the crabgrass clumps using a hose-end or backpack sprayer prevents unnecessary chemical exposure to the sensitive grass. Post-emergent application is most effective when the crabgrass is small and actively growing, and when temperatures are below 90°F.
Long-Term Cultural Practices for Control
Sustainable crabgrass management relies on cultivating a dense, healthy turf that naturally outcompetes the weed for light, water, and nutrients. Crabgrass requires sunlight to germinate, making a thick lawn the first line of defense. Mowing at the highest recommended setting for your turf type, typically between three and four inches, creates shade that prevents sunlight from reaching the soil surface.
Proper watering techniques also discourage crabgrass while promoting deep root growth in the desirable turf. Instead of shallow, frequent watering, which keeps the soil surface moist and encourages crabgrass germination, lawns should be watered deeply and infrequently. This approach wets the soil to a depth of four to six inches, promoting strong roots that help the turf tolerate heat and drought conditions.
Addressing bare or thin patches in the lawn is a necessary cultural practice, as these areas are prime targets for weed colonization. Overseeding or laying down new sod to fill these voids ensures a continuous, dense turf canopy that blocks the light required for crabgrass seeds to sprout. A dense, well-maintained lawn is the most effective long-term deterrent, reducing the reliance on chemical controls.