How To Kill Crabgrass In Bermuda Grass Without Damaging Your Lawn
Eradicating crabgrass (Digitaria spp.) from a Bermuda grass (Cynodon dactylon) lawn requires leveraging the aggressive, dense growth habit of Bermuda to outcompete the weed while utilizing precise pre-emergent and post-emergent herbicide applications. Because Bermuda is a warm-season turf that goes dormant in winter, timing herbicide windows to soil temperatures rather than calendar dates is the singular key to achieving total eradication without harming the turf.
Pre-Operation & Equipment Checklist
Successfully managing an infestation of crabgrass (Digitaria) demands a systematic approach that marries cultural practices with targeted chemical applications. Because crabgrass is a prolific summer annual that germinates from seed when soil temperatures reach 55 degrees Fahrenheit consistently for three to four consecutive days, equipment preparation and material selection must occur well ahead of green-up.
- Essential Gear, Tools, and Materials: Broadcast or drop spreader for granular applications, calibrated pump-up or backpack sprayer for liquid treatments, high-accuracy soil thermometer, protective personal equipment (nitrile gloves, chemical-resistant boots, eye protection), pre-emergent herbicide containing active ingredients like dithiopyr or prodiamine, post-emergent selective herbicide containing quinclorac or if necessary, non-selective glyphosate for spot-treatment during complete Bermuda dormancy.
- Mandatory Prerequisite Knowledge and Standards: Understanding that Bermuda grass spreads via both stolons (above-ground runners) and rhizomes (below-ground stems) allows it to recover rapidly from selective herbicide stress, whereas crabgrass reproduces exclusively by seed. Soil testing must be performed to maintain a soil pH between 6.0 and 7.0, maximizing Bermuda density and choking out weed propagation.
- Estimated Budget and Duration Benchmarks: Budget between fifty and one hundred and fifty dollars depending on yard square footage and herbicide formulations. Expect an initial time investment of two to four hours for calibration and application, followed by a seasonal maintenance timeline spanning spring through late summer.
Step-by-Step Crabgrass Eradication Workflow
Step 1: Monitor Soil Temperature and Apply Pre-Emergent Herbicide
The most effective way to control crabgrass is to stop it before it breaks the soil surface. Use a digital soil probe to measure temperatures four inches deep in areas that receive direct sunlight. Once soil temperatures stabilize at 50 to 55 degrees Fahrenheit, apply your pre-emergent herbicide before crabgrass seeds germinate. Spread granular products uniformly using a calibrated broadcast spreader, overlapping passes by fifty percent to avoid striping.
Pro-Tip: Apply your spring pre-emergent approximately two weeks before the local forsythia bushes finish blooming, as this natural phenological indicator reliably correlates with soil germination thresholds for Digitaria.
Step 2: Implement Correct Watering and Mowing Protocols
Cultural control is just as vital as chemical intervention. Set your rotary mower blade to a height of one to one-and-a-half inches for hybrid Bermuda varieties, or up to two inches for common Bermuda. Mowing low and frequently forces the Bermuda to spread laterally, creating a tight turf canopy that blocks sunlight from reaching hidden crabgrass seedlings. Irrigate deeply and infrequently—applying one inch of water per week all at once rather than light, daily sprinklings—to encourage deep Bermuda root growth while starving surface-level weed roots of moisture.
Warning: Never scalp your Bermuda lawn after crabgrass has already germinated and begun spreading, as this opens up bare soil patches and gives the invasive grass an unhindered advantage over your turf.
Step 3: Spot-Treat Escaped Weeds with Post-Emergent Herbicide
Despite your best pre-emergent efforts, some crabgrass plants will inevitably breach your defenses, particularly along sidewalks, driveways, and thin turf areas. When weeds reach the one-to-three-leaf stage up to tillering, mix a selective post-emergent herbicide containing quinclorac into your backpack sprayer. Add a non-ionic surfactant according to label instructions to help the spray adhere to the waxy blades of the crabgrass. Spray the target weeds to the point of wetness, taking care to minimize drift onto neighboring ornamentals.
Step 4: Execute Fall Clean-Up and Preventative Seeding/Sodding
Mature crabgrass plants produce thousands of seeds before dying off with the first autumn frost. Prevent these seeds from compounding next year's infestation by applying a split-application pre-emergent herbicide in late summer (typically August or September) to catch the second flush of crabgrass growth. If the infestation left large bare spots in your Bermuda turf, plug those areas with healthy Bermuda plugs or lay square sod pieces while the grass is still actively growing in late spring or mid-summer.
Avoid Crabgrass With Expert Bermuda Grass Care in Hampton, GA | King Green
Herbicide Formulations and Application Parameters
| Active Ingredient | Action Type | Ideal Timing | Target Stage | Safety for Bermuda Turf |
|---|---|---|---|---|
| Prodiamine | Pre-Emergent | Early Spring / Late Summer | Pre-germination | Extremely Safe (Established Turf) |
| Dithiopyr | Pre & Early Post | Early Spring | Pre-term / 1-to-2 leaf | Safe on Established Bermuda |
| Quinclorac | Post-Emergent | Late Spring / Summer | Seedling to Tillering | Safe (May cause temporary yellowing) |
| Glyphosate | Post (Non-Selective) | Winter | Full Maturity | Only safe when Bermuda is 100% dormant |
Common Site Failures and Field Fixes
- Root Cause: Applying pre-emergent herbicide too late in the season after soil temperatures have already exceeded 55 degrees Fahrenheit.
- Action Field Fix: Immediately switch strategies to a selective post-emergent herbicide containing quinclorac, and schedule your pre-emergent application three weeks earlier the following calendar year.
- Root Cause: Inaccurate spreader calibration leading to uneven chemical distribution, resulting in striping and weed survival in gaps.
- Action Field Fix: Map your lawn's square footage, weigh out the exact chemical load required per manufacturer specifications, and execute a cross-hatch application pattern (half the rate north-to-south, half east-to-west).
- Root Cause: Irrigating the lawn immediately after a granular pre-emergent application without meeting the required water activation threshold (typically 0.5 inches of rain or irrigation).
- Action Field Fix: Ensure you water in granular pre-emergents within 24 to 48 hours of application to bind the chemical barrier to the soil matrix.
- Root Cause: Applying selective post-emergents during periods of extreme heat and drought stress, resulting in severe turf injury.
- Action Field Fix: Withhold herbicide applications when ambient temperatures exceed 90 degrees Fahrenheit, and water the Bermuda deeply 24 hours prior to any necessary spot-treatment.
Frequently Asked Questions
Can I pull crabgrass by hand instead of using chemicals?
Hand-pulling is effective only for very small infestations or isolated individual plants when the soil is damp. However, if you fail to extract the entire root crown, or if the plant has already set seed heads, hand-pulling will merely shake loose more seeds and worsen the infestation next season.
Will pre-emergent herbicide stop my Bermuda grass from spreading?
No, pre-emergent herbicides inhibit cell division in germinating seeds, whereas established Bermuda spreads via existing root systems, rhizomes, and stolons. Established Bermuda turf will continue to thicken and spread unimpeded by standard pre-emergents like prodiamine or dithiopyr.
Why is my Bermuda turning yellow after I sprayed for crabgrass?
Post-emergent herbicides such as quinclorac can cause transient chlorosis (yellowing) in Bermuda grass, particularly if applied during hot weather or at higher-than-recommended rates. This discoloration is normally cosmetic and temporary, and the turf typically recovers its natural dark green color within 14 days.
When is the absolute best time of year to kill crabgrass in Bermuda?
The single most effective window is early spring just before the crabgrass seeds germinate, utilizing a pre-emergent herbicide. Catching the weed before it sprouts eliminates the need for aggressive post-emergent spraying later in the summer when the turf is stressed by heat.
Does mowing height impact crabgrass growth in Bermuda lawns?
Yes, scalping or mowing your Bermuda lawn too high reduces turf density and lets sunlight penetrate to the soil surface, triggering crabgrass seed germination. Maintaining a tight, low mow height forces Bermuda to form a dense carpet that naturally chokes out weed seedlings.
Transform your thin turf into a dense, weed-free landscape by mastering seasonal herbicide schedules and cultural management techniques tailored specifically for Bermuda grass. Take control of your lawn today with precision pre-emergent applications and robust turf maintenance practices.
